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The mayflies of Florida (Ephemeroptera)

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The mayflies of Florida (Ephemeroptera)
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Berner, Lewis, 1915-
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English
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1 volume : ; 28 cm

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Subjects / Keywords:
Adult insects ( jstor )
Creeks ( jstor )
Eggs ( jstor )
Female animals ( jstor )
Insects ( jstor )
Nymphs ( jstor )
Rivers ( jstor )
Species ( jstor )
Streams ( jstor )
Vegetation ( jstor )
Mayflies ( fast )
Neuroptera ( fast )
Florida ( fast )
City of Apalachicola ( local )
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bibliography ( marcgt )
theses ( marcgt )
non-fiction ( marcgt )

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Bibliography:
Includes bibliographical references (leaves 439-446).
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Manuscript copy.
General Note:
Vita.

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University of Florida
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This item is presumed in the public domain according to the terms of the Retrospective Dissertation Scanning (RDS) policy, which may be viewed at http://ufdc.ufl.edu/AA00007596/00001. The University of Florida George A. Smathers Libraries respect the intellectual property rights of others and do not claim any copyright interest in this item. Users of this work have responsibility for determining copyright status prior to reusing, publishing or reproducing this item for purposes other than what is allowed by fair use or other copyright exemptions. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder. The Smathers Libraries would like to learn more about this item and invite individuals or organizations to contact the RDS coordinator (ufdissertations@uflib.ufl.edu) with any additional information they can provide.
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THE MAYFLIES OF FLORIDA

(EPHEMEROPTERA)













By

LEWIS BERNER


A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY












UNIVERSITY OF FLORIDA
June, 1941











TABLE OF CONENTS


The mayflies of Florida

Historical review 3.ee...... eee.ee.e. eoe... . ee..... e..o

The problem ee*eeoee.eoe ..o...e.oeeoooe ooeeeeeeoe .eo 7 The order Ephemeroptera o*.......oooe e.o*..ee.oooe.e 9

Primitive and speoalised characters .***eoeeeeeeeeeeeo.e 13 The families of mayflies eoeeeeee.oooe.ee.eoee 22 The win& venmtion of mayflies eeeeeeeoeeeoeeeeee .e.eeee 25 Taxonion oharacters e eeeee eeeeeoeeeeeee ..ee 27 A omparison of Florida mayflies with the northern fauna o... 33



Comparative abundance e e.ee.ee ..ee ..eeeeoeeoe.ee..eeeee 35 CoMprative eology eeeeeeeeeeee.eee .eeee.eeeeeeoe. 36 Comparison of life histories ..eeeoee .eeo ...ee.eee.e. 38 Zoogeography eeoeeeeeoeo.eeeeeeee e..eeoeee ..e....ee 41

Dispersal of mayflies e 45 Climatic divisions of Florida eee.e..eeeeee .eeee .eee .ee 49 The habitats of Florida mayflies ..eo.eoe.ee.eee.eoeeee.ee.oe 51

Descriptions of habitats ..e.oo.....ooo.ee...ee.eeoeeoee.. 52

Streams 52eeeeeo ..eo .eeeeeeeeee eeee 52

Intermittent creeks eeeeeeeeeeeeeeeee ee.eeeeee 52 Permanent creeks o*eeeeeeoeoeeeeeeeeeeoeeeoe.eeeeeoo 53

Sand-bottom creeks with little vegetation se.see 53 Sand-bottom creeks chokad with vegetation ee� .. 54 Silt-bottom creeks with little vegetation ee.. 55 Silt-bottom creeks ohoked with vegetation 0.69... 56 . 2Q 75











Rivers 56eee*.*9.*eo.ooe. .eo..o. 5

Stagnant rivers ...........e.....58

Slowly-flowing, deep rivers 57....eo...oooo.o.. 57

ILarger calcareous streams ........... 58

DitOhs and puddles eseoe**eeee eeeeeee ee 9

Roadside ditches *...... ...*......*59

Puddles ***,*g**e*g~****

Ponds d oo0ee oeeeeeeeeeeeeeeeeoeeeeeee 60

Sink-hole ponds .ooo.ooeoc.. .e.......o.o.os,.. 61

Ponds with the surface free of vegetation *.ooe* 61 Ponds with the surfaoe covered with vegetation.. 62

Fluctuating ponds oeooe oeo *. o..eee ....63



SporadO ponds OO......o...e.*.oo ..o......64

Jerome sink ......,..,...........65





Silt-bottom lakes ...*..*e .a.. e~*s..67

Disappearing labms .................68



The Everglades *9eeoooeeeeeeee*.oo~eeoeee. 69

Swamps *o.......................... 71

Cypress wumps .................. 71



Springs ............. .e..*..e.. 71

A0oowledgements *..08 oee.eeoeoe**.*....











A ky to the mayflies of Florida eeooo9.o.ooo.oso**toss**** 75



Be adtha ooeoooooeoo*ooeoeoooooeeeeeeoeeeoooeeeoeeooe* 10 Nympha *oegoeogeeeoee. .e.e..oeoeoee...eeo..e.eo.s 87

8tenO]Oma ....ee.e..e o.ee.... ...e.*eeeeeee~ooeeeeeeegge 100

8. mIlOha *oeoggggg*~ggeeeeeeoeeeeeeeeeeoeeoeeoeeee 101 8# exiguiu 1eeeeo3eeeeggoeeeeeeoeoeoeeoeoee 1 So PrOzIm ooooo~ootwo~otooooooooo 127


H& J!!hIU o*go**googog.e*eoeeeeee ee eee.o.eeee.*oe.6eo 140 H. OFL eeeeee eeeee eoeeeeeeeee eeeeoeeeg 140 H. w. *gfgteeeeeeoeeoeeggeeoeeeeeeeee*ggg 151



C. emlpslO . .eeertgg ,,**.eeogeeegogoe. e,..,.,og... 157
He bi ,i ,,ats, ,g,.......,,** ...,. e.. ... ... ,. . 162

SaeOea o...mulan g*ggg*g*g*gg**g*g.*...gggggg*o.- 165 C_.urdus idortus g.ge*..ee.o..,.g...*g. *.g.,.... 169

Oreianthus .. eggg,,,.,o,*ggg ogggg,.,e.,.,g* g. , 172

'Oreionthus spe No* 1*.**oo* .g.*****g.og�*-*o*.ggg.* 173 S iphlioleaton *1eeeeeoeeee7eee9eeeeeeeeeee 8eeoeeee 179

OR**#~g~Cg*0**g*gO0#CsguOng~* 180
Isonyohia egegeggggeggegeeeesa.eg.ogg185

Itrdoo .d..i.do 1..9......................,. 1

Ap, -&P ! ....* ...*....*g...***. ... 196
IsOomi&a.pe B g~egeg.e~g~gge~gge~~eg198 Igoro~h:a spe G gegg~eg..~e~eeegggeeee201 Blasturua s ege.eggggeeggegee..ggs~g 202

B. intermedius gseggegege.geggeggt ggg203 Paraleptophiebiftggeeeggeegggegge~egeee 215










Pe volitans s.ooooooo.oo~oooo~ogoeeogooo090oeoooo.0 216 P. bradl............... 6.................... 224

Habrophlebiodes .......o.,.o.e.,,,o..o.oeo..,,,. 229



Chorot*!Zs~ 2"4



Sph ulla *.... . .. .... ..90... . .,,... .. . . .. . . ... .26





ChlorythoI.... .*...e.......e...o..,eoeoee*e*o.e.*.*oe 288
Co hubbelli *oee~~~oeo~eoeeeoeoeoe, 2"4 HabTphloblia tus o.ee.ee. 0***0 o 00e00ooe@*9006e.e...... 25

He v*brw3S ****o o*q*06*9* @600000 , *00@0000@0@0*9*6096.e 252

Bme roeo 5



.O dimizuata 0ee*o 9 0o9o S@9eo 9e*o6oo * 069eo 0060e 000g** 026








C . hiriso. *................g...........,.......*......... 318
'So aoulaohloola 276o,......o.. ,.....o...o. 26



Zeo h i i ii il8

rioor,,thogon ...................................... 288

To albtinosu ,,,,.,,0,,o -o., 290 Caon.i8s ,,,,,,,,,,,,,o,,,,,o,,,,,,. 299

C* dLainua 3 301 Co hilars , 318 ,Br ohy oprous , , , , , , . * , , o ., . , , , , , , . , , , 322


Be inOtl eoeeeeeeeeeeeee~oeeee 330 C k l l b & o t i n 3 32oe e e e e ~ e e e e e e e o . e e e e o s e



Es pratiosue ,,o,, ,,,,,.,.,,,,ooo 345











Acentrella 36o. .o... ....0.,.....o...0.g ..o....oo. 350

Ae ephippiatus ....o.... .o ...... eOeeoo..351

A, propinguu ,...***.............o..... 357

Baotia *60eogooegeeeeggeoeeooegegggooooooooeeeggo. 30

B spinosus 362ooogggo.ggo*oegeooeoeeeoooeo. 3 Bo australis oo 375eoeeoo eoogoeeegog**oeeoo g.*ogo* 375 B. interoalarls *.ogg,**.*.goo*goo.*..e.o*,...... 381

,Rs slnithi 87 *oo gge g.o ..eeoo oo ooe soooo.ooo oeoeoo 8 ceop111I~m too.*****g~g~ogg~eooge.o..g. 396

Ca viridooulari.*...**. *..o*..*..***...e*.*.*e.-e..*... 397

C, hobbes o 405 Cloeon rub o ..o ,.g**gego..eg.eo.**.,.aoo,..oo 409



Paoudoolooon .......***. ...o.o,......,o. 418


Pe parwulum oo,,,.,,,,,,,,.,.o.,o,429
-m
P. purva on ggoeog.o. .e.gg.....g ...gg...... 42
16 p!iivntria oo.oo.goooosooooooooO 432 P. bimaoulatus .og.ooeoaeoggggggegegqe, ggoo.o.oe 434 Reorenos *ggggggg.. eqgggggggggg g..439 Biog aphy ".. goggogg.ggggooegg. o.gg.e.oogeoo 447














THE MAYFLIES UF FLORIDA



Few orders of insects have been so little studied in Florida as the

mayflies, or Ephemeroptera. The fragile, delioate- winged adults, requiring special methods of collection and preservation, have not been favorite objects of entomological study; and the same is true of the small and

often inoonspiouous aquatic nymphs of these insects. The objects of the present study have been to determine what species occur in Florida, where they are found, where and how they live, and as much as possible concerning their life histories. Four years have been devoted to this endeavor, in the course of which much of the state has been examined, about forty thousand specimens have been collected, numerous species of mayflies have been reared, and much ecological information has been obtained about the group.

Although the Ephemeroptera include no enemies of agriculture, and

at first glance would appear to have little or no economic importance, such an impression is altogether erroneous. The entire economy of aquatic life is intimately bound up with the presence and abundaxce of mayflies, and it has been demonstrated time and again that these insects, in both immature and adult stages, constitute an important item in the diet of many species of fish, or in that of other organisms that in turn are eaten by fish. The words of Frison (1935s 284-285) apply with particular force to the study of the epnemerids. He says: "The insect life of our inland streams [and lakes] affords a most interesting and profitable field for investigation; and the sooner we learn to place and evaluate this fauna correctly, the sooner we will be in a position to formulate conclusions and generali-











zations of importance in our efforts to understand our aquatic resources and to forward their intelligent.use."

One of the most beautifully written descriptions of the life and

matin- of these insects is given in poetic prose by William Bartram (1794) in his "Travels through North and South Carolina, Georgia, East and West Florida", in which he refers to the mayflies seen along the St. Johns river. Nearly sixty years passO before Ephemeroptera were again noted in the state, when Francis Walker, in 1853, described the tiny Caenis diminuta from St. Johns Bluff on the St. Johns river. Not until 1900 was the group once more reported from Florida; in that year Dr. Nathan Banks described a new species, Callibaetis floridanus, from south Florida* In 1931 Dr. Je Re Traver described Jiexagenia weewa and Hexania orlando from the state. "Ureiantnus ape No. " was recorded from Florida by Dr. Traver in 1935, and in 1937 she gave a full description of the nymph. Four additional species of mayflies were described by myself in 1940, bringing the total list in the literature to nine species. In the present paper thirty-eight additional Florida species are discussed, sixteen of which are considered to be new forms. The descriptions of the new species must await future publioations.

Only a single paper dealing with the biology of Florida mayflies in any other than a taxonomic sense has appeared. This paper (Berner, 1941) describes and discusses ovoviviparity in the mayflies of the genus Calli. bastis, with particular reference to the Florida species.

The recent book, "The Biology of Mayflies" by J. G. Needham, J. R. Traver, and Yin-ChL Hsu, has summarized our knowledge of the mayflies of North America north of Mexico, and brought it up to date (1935). Naturally,











there must be limitations to a book of this sort, and a certain number of criticisms have been leveled at it., some quite unjustified. Without a shadow of a doubt, the book is extremely useful and has stimulated interest in this formerly much neglected order. The greatest gap is found in the taxonomic section, whioh deals almost entirely with the adult insects. The majority of species are described only as imagos, and many of these only in the male sex, although sexual dimorphism is frequently exhibited among the Ephemeroptera. Nevertheless, the collection of this huge amount of data between two covers has greatly lightened the task of persons beginning a study of this fascinating group of insects.


HISTORICAL WIEW


The history of work on the Ephemeroptera was very thoroughly reviewed by Morgan (1913)s and a brief paragraph alloted to each worker who had contributed to a knowledge of the mayflies up to 1911. Needham in "The

Biology of Mayflies" briefly disoussed the earlier Ephemeropterists, but did not attempt any detailed analysis of the present trends in this field.

A large part of the work on North American mayflies has been of a taxonoeaio nature, but several important studies on morphology, eoology, embryology, and life histories have been made* Taking up the account with the year 1911, to which date Morgan's summary extends, the following important contributions deserve mention.

Jo Go Needham published an important study of the genus Haex~a in 1920, dealin- with taxonomic as well as ecological problems. Taxonomic studies by this author apieared o,-casionally from the years 1924-1932, until his interest in the Odonata came to fully occupy his time* However,











the great quantities of data on mayflies that he had aocunulated over a period of thirty-five years were not to be lightly set aside, and these were brought together in 1935 in "The Biology of Mayflies," of which Needham is senior author*

Nathan Banks, at the present time, has completely given up work on the Ephemeroptera. Taxonomic papers were published by him in 1914, 1918, and 1924.

We A. Clens, no longer working with the mayflies, has published

papers dealing with a fairly wide range of subjects. In 1913# 1915, and 1924 he dealt with taxonomy and in 1913# 1915, and 1922 principally with life histories* His most Important paper, "An Ecological study of the Mayfly Chirotenetes," appeared in 1917, and is a thorough and very enlightening piece of work. Three other papers by this author discussed mayflies in relation to their availability as fish food.

Ann H. Urn in her more recent papers has treated physiological

problems, mainly oxygen relationships. Her first paper in 1911 was taxonomic with some ecological discussions, and in 1913 she published "A contribution to the Biology of Mayflies." Her two other papers dealing with mayflies include a study of venation (1911) and a description of the mating flight of a South American species of Campeurus (1929).

Helen E. Murphy has contributed but a single paper dealing with North Ameri'aan mayfliessand in it she describes the complete life history of

Baetis vagans (1922).

G S. Dodds and F. L, Hisaw in 1924 published "Adaptations of Mayfly

Vymp;-s to Swift streams," a paper which has proven to be extremely important. The former author also published a paper on the mayflies of Colorado (1923).











Re J. Tillyard (deceased), although publishing almost exclusively

on exotic Ephemeroptera, has oontributed to the knowledge of North American mayflies chiefly through his elucidation of win,- venation and paleoentomological work.

Fe M, Carpenter has recently begun studies on paleoentmology. His first paper relating to fossil mayflies appeared in 1933.

J. A. Lestage, of Belgium, has worked principally with European mayflies in a taxonomic sense; however, he has made studes of certain families which also oocur in North America# and has included our forms in his discussions.

eorg Ulmer, nearly all of whose publications have been in German, has worked very little with the North American fauna. His studies have been entirely taxononic, and of these his paper listing the -enera of the mayflies of the world in the form of a key is most useful. He has described two genera of mayflies frcm North America, Habrophlebiodes and Trioorythodes.

Ferris Neave published an extremely interesting study on the migratory habits of Blasturus oupidue in 1930. His other work (1929, 1932, and 1934) has been of an ecological nature and has proven to be very enlightening. He is no longer working with the Ephemeroptera.

J MoDunnough has described more species of North American Ephemeroptera than any other taxonomist. His first paper dealing with the group appeared in 1921, and since that date numerous descriptions of new species have regularly been published. Through Dr. MoDunnough's work, the mayfly fauna of the northern part of North America is now rather wll known, and its taxonomy appears to be established on a firm basis.

F. P. Ide first published a taxonomic and ecological treatment of











certain Canadian mayflies in 1930, and since has written two other papers which are principally of a taxonomic nature. Riot most important contributions, however, are his e:' cellent studies on the postembryonic development of mayfly nymphs and the effect of temperature on the distribution of mayfly nymphs in a stream. At present, he is conducting quantitative investigations on the insect fauna of streams with particular emphasis on

the epheseridse

II. T. Spieth has published papers of a taxonomic nature within the

last throe years as well as studies on the coloration of mayflies and the rearing of nymphs. Iia paper on "The Phylogeny of Some Mayfly Genera" has been exceedingly useful to students of evolution and has aroused much interest in phylogenstio work among the Ephemeropteristso At present, his work is mostly taxonomio*

Jay R. Traver is second only to Dr. MoDunnough in nunber of speoies she has described. Her first taxonomic paper on the genus Hexagenia was published in 1931, and since then nmuerous descriptions of now species have

appeared* Dr. Traver's North Carolina work was particularly interesting for it clearly showed Just how poorly the fauna of the southeast is known* One of her most important works is the taxonomic portion of "The Biology of Mayflies," Her more recent papers have dealt with exotic mayflies@

The present tendencies among the phemeropterists are still taxonomic to a reat extent, but phylogeny, distribution and ecological studies are be inning to move into the foreground. Because of an awakening realization of the fundamental importance of" our natural resources, ecological studies of the Lphemeroptera, as vell as of other aquatic insects, will probably soon overshadow the present taxonomic research, but before such studies











can be made a taxonomic system writh a firm and logical basis mu.t be erected. Such a system is within sight, but until mary, many more regions are thoroughly investigated, a sound and comprehensive classificaticn cannot be attained. Particular emphasis needs to be paid the i-mature stages, for it is in the rnymphal form that the mayflies spend almost their entire life, and it is this stage that is important in the econoy of waterse


THE PROBLEM


In a study of this nature, it is rather difficult to point to one

partioular phase and say, "this is the problems" rather it would be more profitable to generalize by oonsidering it not as a problem but as a project which van never be eompleted. When one deals with organisms, the constantly changing environment a the constantly ehangia orgudsms are factors which are much too complex to be understood in all their interrelationships. The understanding of the organiss is by far the more difficult, and we, with our present means, can hope only to secure a superficial 1=owledge of the wor-in:s of livi.g beings.

So far as posbible I have studied the Sphemeroptera of Florida as

living entities rather than as dead, pickled specimens; however, much of the work necessarily involved the employment of dead insects. Because of the far greater intrinsic interest in the living rather than the preserved animal, I have tried to stress the ecology, life histories, and habits of Florida mayflies. I borrow the following from 'ells, uley, and dells "The 6cieuoe of Life" who in turn borrowd it frzm Sir Thomas �"rown's "Ant's, Bees, and piders" to illustrate how wonderfully made insects really are: "Ruder heads at nd amazed at those prodigious pieces of Nature -











hales, Elephants, dromedaries and Camels; thece, I confess are the Colossus ad :ajestic pieces of her hand; but in these narrow Engines there is more curious iathematioks."

The ephemerids of Florida being so little known, it was certain that a study of these insects would reveal much that was new. The only other region in the south that had been at all intensively investigated was North Carolina (principally from a taxonomic viewpoint), and since the fauna of North Carolina is, for the most part, characteristic of mountains and hilly ;ountry, it gave little indication of what was to be expected in the lowland areas of the more southern Coastal Plain and the flat peninsula of Florida.

The approach has been from the standpoints of taxonomy, zoogeography, eoology, life histories, habits, and phylogenys All of these fi~id5 of study were kept in mind throughout the period of research, ad in presentation of the results uniformity of treatment of each species is attempted. however, as would be expected, there may be much information on one species, while anot ier goes begginge. This is the natural result of the relative accessibility or inaccessibility of the species to a student working from the University.

In order to determine Just which species occurred in Florida, where each lived, how it lived, and the various features of its behavior and activities, much travel vas necessary, for a relatively small percentage of Florida species o.cur within easily available situations near Gainesville. Great gaps still exist in the information gathered in the western part of Florida, and only with bluch further work will these be filled in*

6inoe the mayflies of the whole state are included in the study, and











sicc large areas had to be examined in a relatively short time, but few L,4jsical data were secured, This is naturally regrettable but unavoidable.


THE ORDER EPHEEROPTERA


The order Ep:.eeroptera is a natural Zrouping of primitivepterygote inseetz. In &oneral, the fore wings are delicate, membranous, and triangular in outline, and usually have interealary veins and many cross veins; the hind wings are much smaller than the fore wings and may sometimes be wanting. The wings are normally held vertically over the back when the insects are at rest. The mouth parts of the adult are vestigial and the alimentary tract has undergone modifications fitting it as an aerostatic organ. There are ton abdominal segents, and from the posterior ed of the abdomen either two or three caudal filameazs arise. The immaturea are .Auatic and undergo a hemimetabolous development. The mouth parts of the nymphs are well developed for chewing; they possess two or three caudal filaments; and gills are present on certain of the abdaainal segments. I yflies are the only inseots which molt after they have attained funmtional wings; prior to this final molt they are spoken of as subimagos.

The imago, or final adult form, can in most instances be easily differentiated from the subiaago by several characteristics. The wings of the subimago are dull and. Grayish, while those of the adult are normally glistening and Irridesce.; the hind margin of the wings of the subimao are ciliated 5Iile those of the adult (except in the LCaenilnae and TrioorytIodes) are bare; the body of the subimago is dull 'wile that of the adult is glossy; ti.e fore legs of the subimuao are relatively short while they become much elongated in the imago, particularly the male; the caudal fila-











ments are someiWat hairy and relatively short in the subiao, but usually lose this hairy condition and become elongated in the imago; and in the males which have divided compound eyes, these are loss prominent aid rather dull in the subimago and very prominent and glossy in the imago.

The eggs of nearly all mayflies are laid in fresh water, where a varying period is required for development to take place. The freshly hatched nymphs possess no gills, ;ut with-n one to three molts these structures make their appearance; the mouthparts, hog, ever, are all present, though geeralized and simple in form. Soon the nymphs assume the body shape and structure which taey retain over most of their nymphal life. In the few species, the life history of which has been completely worked out, there are at least twenty-five preadult moltsand in most oases more than

ziumer are though to occur, some species requiring as many as fortyive.

The nymphs of mayflies are adapted to their environments in many and

various ways, though they all share certain features in common, such as gills, caudal filaments, and chewing mouthparts. (A species recently described by Spieth lacks the molar area on the mandibles). The burrowing species exhibit some of the mozt remarkable adaptive characteristics; in these nymplis the legs have become flattened, digging structures -- the Lore legs are used for pushing the silt aside, the hind legs for passing it back out of the burrow. The frontal process of the head and the greatly elongated tusks, or rami, of the mandibles first encounter the silt in the digging process, loosening it so that tne legs may complete the task of excavation and removing the material. The gills of thebe burrowers are feathery and thorouhly penetrated by tracheae, so that there is a par-











tioulary efficient mechanism for obtaining oxygen* Even the feeding habits have become modified to such an extent that these nymphs, much like earthworms, eat the organic materials encountered in their burrowing; however, they seem to feed somewhat selectively, since surprisingly little sand is found in their digestive tractse

Numerous other distinctive modifications of form and structure are

encountered among those nymphs which do not burrow, and they are directly related to the habits and habitats in which the nymphs normally live. Dodds and Hisaw (1924) have shown that nymphs which live on the undersides of rooks in mid-streax, where there is almost no current, have flattened bodies# while the bodies of those inhabiting the swiftest waters are torpedo shaped. Still others with rounded, streamlined bodies dwell in ponds, but here it is the ability to swim and dart about rapidly that is correlated with the streamlined form.

I have found that there is a definite correlation between claw size

and habitat. Those species which dwell in ponds and in very slowly flowing water have thin, attenuated claws which lightly touch the object to which the insect is clinging, but they do not form a strong clamp* A nymph with such long claws would probably have difficulty in maintaining itself in a strong current, for the claws could scarcely have sufficient leverage to support the insect in this situation. The mayflies living in swifter currents have short, thick claws which clamp firmly into the object on which the insect is living. The stronger the current, in general, the shorter and thicker the claws. Mayflies from rapids have very short thick olawsp often with strong teeth on the underside, and in one species that I have examined this pectination has gone so far that the entire tarsal











claw has become a comb-like structure and the major claw is no longer distinct. For the most part# the size of the tarsal laws is fairly uniform within a genus, but this is not always so. In one genus, Centroptlun there are two Florida species, one of which (viridocularia) occupies slowly flowing, the other (hobbsi) swiftly flowing water. In viridocularis the claws are three-fourths as long as their respective tarsi, while in hobbai the claws are only one-half as long as their respective tarsi.

The nymphal leg struature, even in the non-burrowers, is correlated with the habitat* Those species inhabiting ponds and relatively quiet waters have rather elongated limbs which stand out from the body, holding it above the object to which the nymph is attached. The sprawlers have shorterthicker legs, the femora being somewhat broadened; the legs are held out horizontally from the body and do not serve to lift the insect from the surface on whieh it is crawling. The lingers of swift water have thickened, shortened legs with a correspondingly greater development of the muscles. Their legs are held horizontally with the femora close to the body the latter are thin along the anterior edge but relatively thicker posteriorly, thus presenting lessened resistance to the current*

The caudal filaments show special features in the freely swimming and darting mayfly nymphs* In these species, there is a great development of hairs medially from the lateral filaments and laterally from the median filament so that these hairs overlap to form a paddle. By rapidly flicking the abdomen and holding the tails stiffly, a very efficient swimming organ is formed and the insects can move rapidly through the water. Those species which swim little or not at all have a correspondingly small development of hairs on the caudal filaments, and in some of these nymphs the











tails are almost bare.


PRIMITIVE AND SPECIALIZED CHARACTERS


It is frequently said that mayflies are primitive insects, and it is certainly true that many primitive characteristics are exhibited by this order. "Luring the Carboniferous period, or probably earlier, a group of winged insects evolved a mechanism in the wing base for fleming the wings horizontally over the back when not in use. The descendents of this group (Neopterygota.) include the majority of modern winged insects, while the more primitive nonwing-flexing inseots are represented today by only two orders (Odonata and Ephemerida), both of which have descended from Carboniferous times but are not closely related to each other*" (Snodgrass, 1935, 12). The earliest known fossil insects identifiable as mayflies were taken from Permian shales. These early mayflies were long-winged, long-bodied inseots with slender legs and three long tails. The fore and hind wings were of nearly equal size and the wing veins were very well developed. Fossil mayfly nymphs taken from Jurassic beds in Siberia seem to have gills on nine abdominal segments.

The fore wings of the more generalized mayflies possess nearly all the veins of the archetype venation* The oostal vein is rather short, running only as far as the humeral braces, and from thence outwards to the edge of the wing; the fore margin consists of a slightly thickened, folded wing membrane beyond the costa. The suboosta extends from the wing base

to the apex of the wing, while the radius branches a short distance from the wing base to give rise to R1, which runs parallel to the suboosta, and to the radial sector, which in turn divides. The ftdial sector forms R2











R3, and R4 plus R6; R4and R5 make up a single vein and the terminology is used only to prevent confusion. The media is represented by both its primitive branches, the anterior media (lost in the Neopterygta) and the posterior media; and the oubitus is likewise represented by the anterior and posterior cubitus. The Ephemeroptera are the only modern insects in which both branches of the media presist. The number of anal veins varies fru one to three according to the genus.

In the hind wings of the more primitive genera the venation is but little modified from that of the fore wings; however# with the shortening of the wing the area occupied by Re has beooue smaller and R3 has disappeared.

The genitalia of mayflies are likewise primitive. Imms (1931: 41)

states that "a very primitive condition is found among Ephemeroptera, where the penis lobes, instead of being fused to form an aedeagus, are relatively large and entirely free, with the parameres closely applied to them." A styliger plate is borne on the terminal end of tie ninth sternum, and forceps arise from tne posterior edge of the styliger plate. The penes are considered to arise from the ninth segment and protrude between the ninth

and tenth segments. "The styliger plate of the mayflies is interpreted by Crampton and Walker as representing coxites, which have fused together to form a single structure. This structure, however, is separate from the ninth sternite. A parallel condition is to be found, according to Walker, in the Phasmoidea and Acridoidea, except that in these groups the styli are lacking." (Spieth, 1933: 73). The forceps of the male Ephemeroptera are homologues cf styli, and in all mayfly genera, except Caenis Brachycerouss and Campurus are segmented. In the females, the oviducts open to the outside or into a common vestibule formed as a fold of the thin membrane











joining the sevent' and eighth segments. The sternm of segment seven is produced backward to form a structure known as an egg valve, but no true ovipositor is formed; however, in some of the Leptophlebine mayflies there is the beginning of such a structure (see fig. )

The abdomen of mayflies, although possessing only ten distinct segments, is nevertheless considered to be quite primitive. The usual ntuber of segments in the abdomen of modern insects is ten or eleven, but embryological evidence inricates that the number of sepents of the early insects was

twelve. The geivralized form of an abdominal segment is approximately retained in those larval forms which preserve rudiments of the abdominal appendages. In mayflies each gill-bearing segment is distinctly divided into a dorsum and a venter by large lateroventral lobes supporting the gill. These lobes represent the bases of abdominal appendages. Snodgrass concludes that there is little doubt that the gills of mayflies are appendicular parts of abdominal limbs, of which the supporting lobes are the bases. "The gill stalk or giil plate, by its position on the basis and its basal musculature, sugostb that It is the hcuologue of the stylus of the thymanuran abdominal appendages. The gill basis is very evidently the equivalent of the stylusbearing plates of the Maohilidae, though since it is immovable, there are no body muscles inserted upon it*" (Snodgrass, 193S5 273).

In order to arrive at any conclusions as to the primitiveness of the

mouthparts of the L~hemeroptera, it is necessary to turn to the nymphal stages. The mayfly mouthparts are of the mandibulate type throughout the order, consisting of a labrum, hypopharynx, a pair of mandiblese a pair of maxillae, and a labium. The mandibles of most mayflies are very generalized in possessing a ventral incisor area and an inner or dorsal molar surface. Between











the incisor and molar areas there is a small structure called the lacinia mobilis, the function of which is unknown. This structure has been interpreted by some as a mandibular palp and a prostheoa., but according to Crampton it cannot represent a true palp. This author has suggested that the mandibles of mayflies in some respects approach those found in the Crustacea. Attached as lateral lobes of the hypopharynx, are a pair of superlinguae, Superlinguae are best developed in apterygote insects and in some of the more primitive members of the Pterygota. The galea, lacinia, stipes, and palptfer are fused in the maxillae of all modern ma .flies, and form a structure called the galea-lacinia, In some of the more primitive genera

it is though that a line of separation can be seen between the gales and lacinia* On the hole, the mazillae of mayflies must be considered as rather specialized*

The primitive condition of the tarsus of adult pterygote insects is thought to be five-segmented; tarsi having fewer than five segments have probably been &peoialited by the loss of or fusion of some of the segments. In the adults of same of the more primitive mayfly Senerea, the tarsi are composed of five freely movable segments, but in most mayflies there is a certain degree of fusion. The legs, therefore, cannot be used as reliable indicators of phylogenetic position of the Ephemeroptera among the other insects.

The gills of mayfly nymphs are thought to be homologous with abdominal legs -- appendages which have been modified for respiratory purposes. Snod. grass states that there is no question but that the gills arise from limblike rudiments of the embryo, and that their structure and musculature suggest that the- are parts at least of true abdominal appendages. The most primi-











tive of the modern mayfly genera bear ills on the first seven abdominal segments and the earliest fossils known had these structures on the first nine segments. The retention of these abdominal structures appears to indicate primitiveness, even thouZh they are present in highly modified and variable forms.

A consideration of the characters discussed abcve will also show that mayflies# while generalized in many respects, are at the same time highly specialized in certain features. As Needham (1935s 207-208) has said, "The group as a .vhole, while retaining a good many primitive characters, has gone a long way in specializing on lines of its own. There arc no very primitive mayflies. There is no one genus or species that caz be set down as ueai-et to the anceatral form in all partioularso The lines ran crisscross here as elsewhere, and do not lend themselves to a serial arrangement*"

One of the principle modifications and specializations undergone by

the wings has been te cephalization of the flight mechanism, with relative enlargement of the fore wings and corresponding reduction of the hind win;'s until, In scie "m, the latter have entirely disappeared. In the specializ. ed genera venation tends to become reduced, and certain of the longitudinal veins become detached and may even be shifted at their bases and reattached* Paralleling this modification of the longitudinal veins, there !s a tendency toward reduction in the number of cross veins in the fore wings, until in the highly specialized genera they may be almost completely absent. At the same time that the cross veins are becoming reduced in number, a series o marginal veinlets develops, occupying the interspaoes between the longitudinal veins. The presence of these voinlets is a mark of greater specialization than the irregular marginal network (the remains of the arahediotyon)











fo: nd in the most primitive mayflies; in the higher genera even the vei. lets may be lost*

The hind wings indicate degree of specialization very clearly, for in the Ephemeroptera there exists a whole series of species ranging from those with vll developed metathoracio wings to those showing complete absence of such structures* In certain of the highly speoialized groups the hind wings are reduced to tiny threadlike rudiments, sometimes so small as to be difficult to find, and which could hardly be of any use as organs of f'liht* The venation of these threadlike wings consists only of one to three longitudinal veins.

The form of the fore wings in the primitive genera of Ephemeroptera is

somewhat triangular With increasing specialization, they have become more elongate and narrower, but in those genera with greatly reduced hind wings there is a tendency for the secondary development of a triangular wing with a well developed anal angle, perhaps in compensation for the partial or complete los of the hind wing. The return to a triangular wing shape reaches its culmination in the highly modified Caeninae, which cmpletely lack

metathoracio wings,

Not only is there a correlation between specialization and reduction in size of the metathoracic wings, but closely linked with it, body size likewise seems to have decreased. It is very likely that as wing size decreased a diminution in body size was a natural consequence, or the reverse. The amount of wing surface for support of the insect being lessened, the necessity for less body weight or an increase in wing surface of the other pair of wirag was encountered. Both conditions have resulted. A diminution of body size parallels the diminution in size of metathoracic wings, with











concomitant changes in shape of the mesothoraoio wings but no relative increase in resulting wing surface. In Caenis, which has entirely lost the hind wings and in which the body is thick and heavy by comparison with that of the Baetinae, the fore wings have become enlarged and broadened considerably at the anal angle. Although certain other genera of mayflies have lost their metathoraoio wings (Pseudooloeon and Cloeon), there has been no such relative increase in size of the fore wings, but the body is lightened to acconodate the lessened wing surface.

There are few specializations in the genitalia of =ayflies; however* in the more advanced genera there appears to be a fusion of se.nents of the forceps, and in Caenis and Braohyeroue this has reached its culmination, the claspers consisting of but a single segment. The rales of the more specialized species also show a fusion of the paired penes, although the vase defferentia still open to the outside separately, and in the Baetia. the penes have become internal.

Although the Leptophlebiinae are not the most highly specialized mayflies, certain of the females have the sternites of the. at,.t a eighth segments modified to form a simple ovipositor. The ovipositor is really nothing more than a prolongation of the e-G valve of other mayflies, and its value in oviposition is entirely unlmown.

All mayflies supposedly have ten abdominal segments; however, in Betisea and the European Prosopistoma there seems to be some amalgazmtion of the

se,-ents, although it is claimed that ten segmentG can be distinguished. The first abdominal segnent of Baetisca is intimately related to the metethorax, and it is only with difficulty that this seEaeut on. be differentiatede Spieth (19W;) considers that in the nymphs of Baetisca gills are found on











segments one through five, but Traver (1935) claims that these structures occur on segments two through six* The latter author states thet segment one is almost oorapletely fused with the thorax, a statement with which I am in agreemente Thus this condition of lessening of number of abdominal sepents, although indicating specialization, is found in a genus which has many primitive characters.

Specializations are not pronounced in the mouthparts of immature mayflies, but the degoneratioxi evinced by adults is certainly a highly modified ooi:dition existing in relatively few insects. The iouthiparts of the adults are reduced in size, asymmetrical in form and lack chitirizalion. Internally, the -zusoulture degenerates. As a whole they are shrunken very closely tcGether in a niiigle whitish mass beneath the clypeus. The greatest modifications in the nymphal mouthparts occur in the burrowing spe ies, where each mandible ives rise to a long tusk used in digging (fig./ . n. 6 fusioiL of the part of the maxillae indicates a specialization in these structures. Spieth states (193: 81) that "even the most primitive maxilla of the mayflies (as is patent from the nature of the -ac- *na-a ...... o: ) is specialized as compared wit- more generalized insect types."

Une of the most interesting specializations undergone by mayflies is in the enormous development of the eyes of males. In the Baetidae the compouid eyes of the male have become completely divided into two parts, a lower rounded structure a.nd a much larger "turbinate" portion capping the smaller part. The om-rtidia of the turbinate eyes have become greatly elon-.tet., ar.6 the she.pe of these eyes is gre tly varied, ri.r.' from a ca-lilhe, flattened structure closely hu-ming the lower eye tc one which e:tends vetically from the head for some distance. In many species the











Utrbinate eyes are brightly colored in shades varyig from yellow to oraxne to br;va.. it is thought that this exoeptioxial i .L of t'e eye. c2 the mules is correlated with the habit of aerial mai', for in this flig-ht the male aipproaohes the female from belowe It has been pointed out by Cooke (140) that the specializations have reaoed such a state of develoaent that if a iaale (o2 ;tenonaa vioarim) be approached by a female :roa bolow, she will be completely ignored, probably because she is invisible to the male; owever, if the female is above the ale, she is L. d;2tely seized and copulation ensues.

The lets of ma.Zlies, although primitive in some respects, are really hihly modified organs. Adult, mayflies do very little walking and no runnin whatsoever. In certain groups, i. e. Campsurus, the legs (except the fore legs of the male) Iave beome vestigial, and the adult can no longer alight but must remain on the wine during ita entire imaginal life. .oricn (192.: 6Z), in her description of the mating fliGit of C. segnis, States that "in the extreme specialization vioh Campsurus senis has attainoe. -h: t of its aerial life has been a neoessary parallel to the abbreviation of its legs. The adults are entirely dependent upon their in for existence. 6ince they have no leis to rest upon neither males nor LAialez can alight upo:n an hklng and if they are forced down there is little chance that they can ever tly again." The forelegs of male mayflies are elongated aid have been provided ith a reversible joint at the base of the tarsus as specializations for seizing the female during the mating light. The more apecialized mayflies show a tendency toward a reduction 4n n.rber of tarsal seGnents in the two posterior pairs of legs by fusion of the basal segments with the tibia.










The alteration of the alimentary tract to suit it for its aerostatic functions is a character common to all mayflies, and it is one which indioates a specialization throughout the order* The modification of the mouthparts, the tremendous development of the ovaries, the enlargement and emptying of the alimentary oanal, the enormous development of the eyes of the males, the elongation of the fore legs of the males, and the development of elaborate copulatory organs all fit the adult mayfly for efficient mating and the oertitude of continuing the speiooes.


THE FAMILIES OF MAYFLIES


There have been many arrangements of mayflies in various families and much buffeting back and forth of the genera* As yet, there is no general agreement as to what constitutes a family and what constitutes a subfamily in the Ephemeroptera. For the sake of uniformity, I shall follow the taxonsmio system set forth by Needham, Traver, and Hsu (1935) in whioh three families of mayflies are recognized to occur in North America, north of Mexico.

Family -- Ephemeridael

Subfamily Ephoronime

R-- phemerimae*
R -- Fotamanthinae

-- Campsurinae*

-- Nooephemerinase

Family - HoptagenUidae

Subfamily -- Heptagenlinae*



l. An asterisk after the subfamily name indicates that representatives are
found in Florida.











Family - Baetidae

Subfamily - Ametropinae

-- Metretopinae*

- Siphlonurinae*

- Leptophlebiinae*

- Bastisoinae*

U - Ephemerollinae*

- Casniznae

m- BaetiMae*

Ulmer's key (1933) to the Ephemeroptera of the world lists three suborders, phomeroidea, Baetoidea, and Heptagenioidea and these in turn are divided into fourteen families. These families of Ulmer# however, in some cases, do not coincide with the subfamilies of Needham and Traver. Spieth, also in 1933p used superfemilies in his discuasion of the phylogeny oei North American mayfliesv and included his genera under the �ollowings Superfamily Siphlonuroideap including the families Siphlonuridae, Heptageniidae, Baetidaes superfamily Ephemeroidea, including the families Leptophlebidae, Sphemeridae, Ephemerellidael Superfamily Caenoidea, including the family Caenidao! and Superfamily Baetisooldeal including the family Baetisoidae. Chernova recently (1938) described a new family of mayflies from Russia, but I have been unable to seoure a copy of this work and can give no information about the grolU.

The usage of the toms suborder, superfamily, family, and subfamily as higher categories appears to be merely a matter of convenience subject to the whims of each particular worker. However, consistency in usage would seem to be desirable, and whether the term family or subfamily is used to











designate these categories is a matter of choice. The taxoncmio system, i. e. the higher categories. set up by Needham a"d Traver appears to be adequate in the present status of our knowledge.

As far as the inclusion of genera within the families and subfamilies is concerned, much more phylogenstio study is necessary before the positions of several of these groups can be satisfactorily determined. Certain genera exhibit characteristics which would place them in either of two subfamilies, and in such oases it is desirable to indicate this overlapping in discussions of these genera. In reality# there are no ,enera of North American mayflies which oalnot be placed rather definitely in the higher categories, except perhaps Isovehia, which has been included both in the ileptageniidae and 2atidae. In this paper, Isonyohia Is considered as belonging to the Baetidae, but the placement is debatable.

Ulmer' s 1933 key to the Ephemeroptera of the world included one hundred fifteen geeras, and since the publication of this work several generic changes and additions have been made. At presents forty-nine genera are recognized as oeourrixg in North Americas north of Mexiooo Since the publication of "The Biology of Mayflies", Acentrella has been re-erected, and Oligoneuria has be'n discovered in the drainage of the Mississippi.

When Traver wrote her taxoncami review of the mayflies of North America in 1935, she included five hundred seven species. Since the publication of this work, forty-two additional species have been described from the region. There are still numerous areas on the North American continent which have barely been touched, and when these are finally worked many more undescribed species wills without doubt, be discovered.











THE WING VENIATION OF MAYFLIES1


The wing venation of mayflies has recently been reviewed by Spieth (1933) and by Needham (1935)o These two authors disagree in their interpretation of one important set of veins. Needham and his followers consider tne radius to be divided into Rl R, R2s, RH, R4, and H5, And that the anterior media is missing frmc the wings of modern ephsmerids. Tillyard, Carpenter, 6pieth, and others adopt the view that the radius is divided into RI, Hs, R2, R3, and S4 plus Rr, and that the anterior media is present* The essential difference between these two view3 rets upon the interpretation of the homologies of one vein in the mid-wingwhioh divides to produce two branohese Needham has named this branched vein the outer fork of the posterior branch of the Rn (OF), while Tillyard and his supporters consider it to be the anterior media* In the present paper the term anterior media is used to designate the vein in question* In all other respects, there is full agreement between the two groups of workers concerning the generalized nature of the venation of mayflies*

Mayflies are unique among pterygote insects in completeness of fluting of the wings. T here is a regular alternation of high and low veins, or convex and concave,. A very important feature of the mayfly wing is seen in the relations of the veins -- as shown by Spieth, all convex veins belong to the dorsal surface of the wing and the concave veins to the ventral surfaces "The cross veins blon; principally to the dorsal surface, it e.. at the base where they join the concave veins a stump of the cross vein is attached to the main vein, while on the dorsal surface the cross veins are always complete and vigorously developed.... It is important to note that veinlets at the edge of the wings are always restricted to the 1- The names of wngs vei ns of mayflies have been discussed on pages /3'- /











dorsal surface." (Spieth, 1933t 60).

The triadic type of branohing is also a characteristio feature of mayfly venation. When a longitudinal vein forks, there is interpolated between the two branches a third vein of opposite position, which does not reach tle base of the fork. For example, the anterior media* a convex vein, forms a fork just beyond the middle of the wing (called the outer fork [OF] of the radius by Needham). The two branches of this fork are convexl iiowever, the interoalary vein lying between the two branches is oonave,. This system of fluting is primarily an adaptation for radial strengthening of the wing, and the cross veins serve chiefly to hold the ridges and furrows in plaoe. In the more specialized mayflies, which have small hind wings or none at all# there is a decrease in the number of cross veins while in those species which have large wings with prominent fluting& the cross-yexotion is well developed. This system can be seen to reach its maximum in Ephoron in which there are several hundred cross veins in the fore wings*

The origin of the various wing veins has been studied principally by proponents of the Needham system, Ir. Ann Morgan (1912) conducted a rather intensive investigation into the origin of the definitive adult venationj but in the light of further research by Tillyard and others, some of her results have been found to be erroneous. One of the most

outstanding points of disagreement is that while Morgan interpreted the radial sector and media in the same manner that Needham had interpreted them in Udonata, showing Re crossing the media, more recent studies lend no support to tiis interpretation. There is a complete review of wing tracheation in "The Bic~og' o' Yyflies."











TAXUNOFMIC CHARACTERS


Perhaps taxonomists have not been sufficiently thorough in their treatment of mayflies. All structures or features that have been used taxonomically are external; until students of mayflies overcome their inordinate desire of preserving perfect specimens, the approach by study of internal anatomy will not be used. Of course, the difficulties involved in an investigation of the internal anatomy of small organisms must also be taken into consideration, and when large numbers of individuals are to be examined such studies would obviously be out of the question, Furthermore, although it might be thought that taxonomio studies carried on for so long a time as has been the case in Ephemeropteran work would have resulted in a very thorough knowledge of the external morphology of the insects; however, there are structures which are still imperfectly known, even though they are used to a great extent in taxonomic work.

Of primary importance in the separation of families, genera, and even species, the wing veins of mayflies are even now not satisfactorily understood from the standpoint of hcmologies* The problems of enation have been discussed above in the considerations of phylogeny and venationa The wing veins of each genus of mayflies, and in particular the longitudinal veins, are very constant in structure and position -- so much so that only in few groups can specific differentiation be found, and then only by reference to minute details. Eaton (1883-1888, 4), in his monograph, has clearly summed up this situation "Unstable in minutiae, so closely is the essential plan of the neuration adhered to by nearly related Mayflies, that the general faeles of the wings is an important aid to their classification, affording characteristics as easily recognizable as the style of











branching in the case of' trees*" The highly modified hind wings are very useful in uifferentiating genera within the various subfailies and*in mazW oases, the shape of the costal angulation, the number of longitudinal veins, and the general wing shape and relative proportions of these wings are helpful even in distJonguishing species.

The structure of male genitalia has been widely employed by taxonomists throughout the field of entomology and even in the study of other animals. These reproductive structures are particularly useful in the differentiation of ephemerid species, and have been widely applied. 22U of our present species have been established on genitalia differences alone* but there are usually other characters which parallel such genitalia divergenoest kAch genus has its own peculiar penial shape* and within the gemns there may be iuch variation. Lne of the best examples of this is seen in paraleptophlebia, where each species has a distinctive type of penes. The shape, number of segments, and relative proportions of the forceps or claspers are also very useful in differentiating genera, and in some cases species* The reproductive apparatus of the female mayfly is so poorly developed externally that it is of no use taxonomically, except in those few genera which possess a rudimentary ovipositor.

Lr. Osgood Snmith made a study of the eggs of a number of genera of

mayflies, and found that within a genus the sculpturing and accessory struotures are very uniform. From his study, he was able to construct a key to the known egs of North American mayflies, and this key has been incorporated in "The Biology of Mayflies*"

The number of tarsal segments in the posterior pair of legs of adult

mayflies is a character which has proven useful as a familial differentiator.











Within some families, the length of tarsal segments of the fore legs of the males is used to distinguish between general and in some oases this charaoter has been relied on to such an extent that it is impossible to identify a female to genus1 unless males can be definitely associated with her. It seems that much further work is needed in these groups in order to clarify the situation* Within the genera, leg structure is little used taxonomieally, although I believe that relative proportions of the various parts will prove useful when measurements are made.

Another character frequently usedg and rightNuly so, is eye structure, but this character again in applicable only to males. sexual dimorphism in mayflies Is so very pronounced that unless one is familiar with the group, males and females of the same speoies might easily be mistakenly placed in different genera. Among the male ephemerids, there are all gradations in structure of the compound eyes from a simple type to those which are completely divided and enormously enlarged into bizarre shapes. l.hether or not the eyes are divided is used as a criterion for separating the Bsetidae frm the Heptagenlidae, and in scme ases the character is siso used as a generic differentiator. There ap ears to be a definite correlation between eye size and shape and the night- or dq'flying habits of the species. Those mayflies mating at dusk or after dark have sall eyes which are approximately of the same size in both sexes, or but slightly larger in the males. In palinge nia (European) the female is approached by the male as she floats on the surface of the water, and in this genus& the eyes of the male are a little smaller than those of the female. The males of the day-flying species have huge eyes whioh are far larger than those of the females.











The colors found in mayflies vary from white through yellow, orange, red, brown, to black* All these colors are rather drab, and aid in making the mayflies as inconspicuous as possible. Spieth has pointed out that the more primitive species have particularly dull and subdued colors. This author found that in the greater number of mayflies the entire exoskoleton is transparent, and if color is present in the ohitin, it is always some shade of olive brown* The tissues immdiately underiying the exoskeleton are often impregnated with pigments which are the principal cause of the distinct adult color pattern. Dr. Spieth found that the white colors in the Ephemeroptera are due to two distinct faotorus (1) in all adults, a chalky white substance is present underneath the exoskleton and the epidermis but external to the musculature (2) certain species have a milky appearance which occurs not only in the body but also on the wings of some species* This is a physical color, which disappears when the insect is immersed in liquids of the same refractive index as that of the white structure, The two types of white combine to form the color pattern of those adults showing this second type of coloration. He also points out that some of the oranges, bright yellows and greenish yellows present in certain species are probably chlorophyll derivatives, since they deteriorate in dried specimens and are completely destroyed by preservatives*

The disposition of pigments in sexually dimorphic species is particularly interesting. The wings and body of both sexes of these forms are brilliant. In the males, however, the pigments are no longer evenly diattibuted in, each abdominal segment but are concentrated in the first and the last four, with the intervening ones hyaline white. There may be











a definite color pattern overlying the white of segments 2-6, but this is never conspicuous. In nearly all cases, this strongly localized coloration is limited to specialized genera of mayflies which are less than ten millimeters in length* It is probable that the glistening wings and the hyaline segments help to render the insects inconspicuous because there is euch a great reduction in the amount of dark color exposed to the view of predators. The females of these species have uniformally colored abdomens, but it has been suggested that if the entire exoskeleton of these insects were transparent the light colored muscles as well as the egg Masses would show through and the females would be easily seen*

Differences in maoulion are reliable, in general, for distinguishing speoies, but the great degree of variability in some species causes misgivings whenever color pattern, unless it is absolutely distinctive, is used. The genus Stenonema is one of the chief groups in which color has been used for the establishment of new species; however it should be employed with oaution. In Floridaa species of Stenonema occurs which by its color pattern might fit into any one of three species, S. proximun (the name used for it in this paper)# . pallidum or S. interpnotatum. Probably (just as a's found to be true of So trpginctatum, described below) S. proximun and pallid= will prove to be local variants or seasonal forms of S. interpunotatum.

To distinguish between species, colorational differences have probably been employed more than any other character or group of characters. Spieth (1938) made a study of coloration and its relation to seasonal emergence in the Ephemeroptera, and frm his study it appears that some of the species# which have been described solely on the basis of maoulation-











al differences, are really only seasonal forms of the s&a.e species. I have been told by Dre. Spieth and Lyman and Mro Jenkins, who have worked in the Great Laks region, thatas an example of this, Stenonema tripunctatu shows. seasonal variation in coloration exceptionally well. Dr. Traver has described several species differentiated from S. tripunotatum by colorational variations, but the other workers mentioned above, through observations during the entire emergence period of the mayflies of a particular region, have found that all of these are seasonal forms of the one species*

Size of adults, including both wing length and body length* has been used to some extent for species determination; however, so many factors modify size thet it is not considered a safe criterion by itself for the erection of species* Wing length within a population is iuoh less variable than is body length, for the latter is subject to shrinkage, elongation swellng, et. when the insect is killed. There has been very little use of relative proportions of wings from a taxonomic standpoint, but this may be worthy of future study.

The families of mayflies as they are set forth in this naper appear to be natural groupings, for the evidence from the adults is substantiated by the structure of the immatures. Needham (19351 208) states "in this order the struggle for existence has fallen largely upon the nymphs, which are better equipped to meet competitors. These show greater divergences in adaptation to their several types of habitat. These have differentiated on lines of their own, independently of the adults, and tell their own story. It goes without saying that out interpretations of nymphal and adult evolution will, when correct, be in agreement. One must corroborate











the other; for nature preserves or eliminates species as wholes."

outhparts and head shape are the familial characters used to separate the families of mayflies in the nymphal stages. The subfamilies,on the other hand, are to a large extent separated by the structure of the mouthparts and the structure of the gills, of which the latter are probably the more important.

Gill shape and structure are extremely varied. They may be foliaoeous, siile or recurved; they may be highly traheate or completely lack these air tubes; they may be present on seven abdominal segments or they may be absent from some of them; they may lie aflat on the abdomen or they may be so shifted that they serve as suckers on the venter of tie insect; they may be modified so that saw form protective covers for others or they may be completely exposed; they may be stron;ly muscled so that they can be vibrated very rapidly or they may be so flabby that such reactions are out of the question; they may be entirely confined to the abdomen or, in a few cases, gills may also occur on the thorax or even on the maxillae. In short, the gills are probably the most Variable structures to be found in the nymphal Ephemeroptera.

Since hind wvngs are absent in the adults of sone species of -ayflies, naturally their immatures lack hind wing pads. The presence or absence of these metathoraoic wing pads is used as a taxonomiec character Vienever possible.

The caudal filaments, two cerci and one median tail, are very useful in studies of the nymphal forms. In some species, these are very flexible orgas, while in others they are sturdy swimming structures. The cerci of many of the genera are densely clothed with hairs medially and











the median tail of these genera has heavy growths laterally; in many others, the three tails are almost bare, having only a light oovering of short hairs*

Color pattern, while frequently used for species determination, is in no wise as frequently employed as in the adults* Often when such charactore are found to distinguish epeoles, sturotural differences parallel them*



A C (&PAR16(iI '.A. FLORID)A MAYFLIES "W1ITi THE NORTHERN FAUNA




The genera of mayflies occurring in Florida, except Oreianthus, are found over the entire eastern part of North America# and even Oreianthus is known as far north as North Carolina* It is of interest to note that many of the genera suoh as &homer C horses, Habwophlebia. Habrophlebiodes, Pseudooloeon, and Tr orhodes have never before been recorded from the Coastal Plain, but all of these are now known to occur in Florida. Trioorybhodes was previously taken no closer to Florida than Texas and West Virginia, while Choroteaes vas recorded only as close as Texas and northern Chio,

Thirteen of.tbt Florida speoes are found also in southern Canada,

Chio, and New York as wll as other areas in the north. In addition, there are several other species which are very similar to those described frm the northern region but which differ in minor oolorational or genitalial eharaotirso .,t is to Le nited that all but one (!exenia bilineata) of these wider nging species are small formse This oonforme with the generali-











tion (for which no explanation is at present forthcoming) that the smallest mayflies are, on the Whole, the most widely disseminated - a generalization that seems to be world-wide in application.

Fifteen species hitherto unknown are here recorded from the state, but nine of them are known only frum the nymphal stage. In addition, four now Florida species have recently been described making a total of nineteen species discovered durinLg the course of this investigation. The total faunal ii6 of forty-seven species from the state seems large for such a small aod (from the staridpoint of mayflies) ecologically limited regi on.

Actually, Florida is poor in number of species compared to those areas which can boast of mountainous, hilly, and coastal regions all within relatively small boundaries. Traver, investigating the mayflies of North Carolina, found more than one hundred different species in the state, but her clleotions included specimens frca three physiographic provinces. Ide (1935) working in Ontario found fiftyfive species in one stream, and I have been informed that subsequently he has taken more than one hundred species frm a single stream. No such concentrations of species art' foun in any Florida stream; conditions do not compare in favorability, In these streams, for mayflies with the rapid, rocky, and well-aerated streams of Ontario. In our most populous streams the maximum nunber of species found is only nineteen, and even this is exceptional (Sweetwater Creek, Liberty county).

In summary, it appears that the Floridian Ephemeropteran fauna is mostly of southern origin; however, there are certain northern elements which have entered the region and which have there succeeded remarkably well.











C onparat ive abundance

in Florida the actual number of individual mayflies that are present in a -iven situation is smaller than that found in northern streams. This fact finds a partial explanation in the relatively small number of suitable mayfly habitats in any particular stream; however, there is a difference in abundance even in corresponding situations* I have examined

mountain creeks in the southern part of North Carolina, and on the undersides of rocks the nuaber of mayflies found greatly exceeded the number Which might be found in analogous situations in Florida. It is necessary to employ tile ten "analogous situations" because in Florida the rook habitats are only rarely presents and the insects use as substitutes submerged logs. boards, eta#

In the smaller rivers and streams descending from the mountains along the east cqast of Mexioo# the nuaber of individual insects on a single rook is amazing. Nearly two hundred mayflies were taken from one rook, approximately 15 x 15 x 8 inches, and one the same rock the caddiefly oases and blackfly larvae literally covered the surface. 1Khen a Flori(-C r -is compared with such a rivers it can be seen that, even thouji mayflies are the predominant insects* they are so much less abundant th.t they can in no wise be as important in food chains as those of the rocky streams

of the north and of Mexico*

Adults of the great majority of Florida species emerge throughout the year, and for this reason there are no great swarms (except in some of the burrowing forms). The flights are small, composed of inconspicuous insects

which d at.er in groups to mate. The literature indicates that many of the small northern forms collect in very large swarms to carry on their mating











flight, but in the areas where such flights occur, the emergoee of those species forming the large swarms is limited to a short period. It has been stated that those species which emerge over a long time -- the entire summer .- will not form large flights, and from these accounts it would seem that in site the flights resemble those of the Florida ephemerids.

The burrowing speoiesbeing more or less seasonal, emerge in great numbers in Florida -- hut not in swarms ocmparable to those described as occurring in the more northerly parts of the country. The lake species, in Vartioular, during their emergence period do form a conspicuous part of the insect fauna in the Central Highlands of Florida, and at this time very likely are important in the food chains of lakas. The number of individuals in the lakes approaches more closely the abundance characteristic of northern regions, than dQes the number occurring in amy other situation in Florida* However, the banta F river might perhaps compare favorably in this respect with sams northern streams*


CM!MtiVS eol

Naturally, the ecological factors are the most important conditions

affecting the distribution of ephemerid species. As indicated above, those habitats suitable for northern mayflies are, for the most part, absent in Florida. Ts.nprature is probably the most important single factor determinit the presence or absence of a species, and current is tied up very closely with this* The great majority of mayflies are rheocolous, and# as Ide has shown, the entire stream fauna is very much affected by thermal conditions. This author has stated that the number of species increases downstream due to the higher temperatures which prevail in the lovmr parts of the stream, and the addition of species in this way is more rapid than the elimination











of species by high temperatures. His analysis of an Ontario stream in terms of temperature is very interesting; but although no such temperature studies have been made on Florida streams, Ide's results are not applicable to them because the temperature is uniform throughout the stream. His conclusions might also lead to the idea that the greatest number of mayfly species should be found in the southern part of Yorth America, where higher temperatures occur throughout the year, but,as was pointed out above, the reverse is true.

The rate of flow of water is also an important factor influenoing

the distributing of mayflies, but even though there are numerous streams in northwestern Florida which have a constant and fairly rapid mcvement, maiV species which occur in North Georgia and North Carolina are not found in them. The interpunctatum complex of tenonema is represented in Florida by c. single species, and this complex (perhaps even the same species that occurs in Florida) also is found in the mountainous streams of Forth Caro. lina. Iron likewise Is found in these North Carolina streams in identical habitats with the Stenonama nymphs. Yet# for some unknown reasor does not seem to be distributed south of the Atlanta region in Jraoria. The degree of tolerance may be greater in the Stenonema species, or nerhaps there may be certain differences in feeding habits which would prevent the spread of Iron.

Habitats within Florida streams are apparently more limited in extent and variety than in northern ones. A great ,many of the northern streams are filled with rocks and pebbles, and this condition evidently affords the OPtimim circumstances for great nuabers of mayfly species. Combined vith the rooks are, of course, pools, vegetation, debris, and many dher











situations ,ich offer refu ;es to the mayfly rnymphs. Flor-i1a streams, devoid of rocks and with much barren, sandy bottom can offer little in comparison, even though in these streams all available habitats are utilized.

Perhaps the greatest barriers to the wide dispersal of northern mayflies in Florida are the wide areas in which there are no constantly flowing streams. Thousands of square miles of the state, particularly in the coastal regions, are low and flat, s"-d the grade of the lowlands is not suifficient to maintain permanently flowing orecks and rivers, Typical

-,eotropIo species cannot exist for long in standing water, and even if a species were accidentally introduced while there was some flow, an soon as the flow ceased, the rymphs would probably die* The dry, sary sorublands of southwest 3eorgia and of Florida also offer a serious barrier to less vaZile species, and this has probably helped to keep the number of mayflies in Florida less than that of neighboring states and the northern part of th-e continent. Rogers (1933) foaud that the same conditions affected the distribution of oraneflies. He states "one of the most important barriers to the northern groups the ranges of which extend into the Piedmont Province of Georgia and the Carolinas, is the monotonous, low pine-la nds o�f the southern coastal p~. in with their dearth of clear fairly rapid& pebblebottom streams...*"


Comparison of Life Histories

Many differences in behavior would be expected between the mayflies of the north and those of the south, but the most striking are found in life histories. Those species of Ephemeroptera which are known to occur both in Canada and in Florida show wide variations in emergence period, and might in consequence be considered different physiological subspecies. In











Canada and the northern states, all of these species have a rather limited period of emergence during late spring and stmimer, but in Florida such is not the oase. Here, every one of the species ommon to both north and south emerges throughout the year except during the cold spells, and mating takes place at any tir-e of the year, unless cold weather is encountered, when the insects become lethargic.

Although Spieth had no definite information on the point, he stated rativnr accurately (1938c, 214) that "in the southern part of the United States, the length of the emergene period of the group is much longer. There seems to be no reason why in the tropics and subtropicc there should not be some species emerging during each month of the year." The greater part of Florida cannot be considered subtropical, yet Spieth's conjecture holds true for the whole area.

This author (Spieth, 1938c: 214) makes one statement whith Which I

cannot agree. "Regardless of the time of emergence during the year, each species has a definite limited period of emergence. In those species which have more than one generation each year, naturally there i- r thean one emergence period. Usually the period of emergence is relatively short." In Florida, the reriod of emergence of the great major.ty of species is not at all lirited, although there may be many broods emerging durin the year. I do not believe that results obtained in the north, upon which Spieth based his conclusions, can be accurately applied to the species inhabitin- Florida.

Yot only are many of the mayflies non-seasonal in Florida, but this has beer found true of other groups of animals as well. Professor J. S. Roers has told me that the life histories of many craneflies are not











seasonally limited in Florida wherea tney are definitely so in the north; tais i-ias been found to be particularly true in the southern part of the peninsula.

Relerenoe to the ao anyin6 temperature map (fig. 1) will show that average temperatures in Florida are suitable, even in winter, for the adult sta~e of insects whioh are primarily of northern origin.

There are very few Florida mayflies which are definitely seasonal and tio iew are probably southern in origin, while those species emerging

-roubghout the year are northern ferns whioh have inai grated into Florida. ai s agrees with observations in other groups, being Lrue not only of the manflies but also, in general, according to 16 Z. Wallaoe of the Lycosid spiders, according io ., i. Oyere of the dragonflies, according to J. So Aogers of the cruneflies, ad4 according to To H. Aubbell of the Orthopteraw This unique behavior appears to be linked with the temperature factor. It ius been shown that in the case of the mayflies the colder the water inhabited by the immatures, the shorter the period of emergence. bince, in Florida, the lowest winter temperature of the water is probably equal to& or slightly Alm# that of the nortlaern waters during the su- er period of emergenoej, mayflies in Florida are soldcior never, confronted with conditions which. are unfavorable for traneformation, For this reason a species (Paraleptophlebia volitans for example) JA ioh in Canada emerges only for about two iw;eeks durin& the summer, can emerge througiout the year in Florida* The generalization that species of northern origin are non-seasonal in Florida, and that seasonal forms ia this state are all of southern origin, holds good; but this is not a complete statement of the facts. Most of the species believed to be southern in origin are non-seasonal like the northern forms











in this area. 1ut this too may be explained on the basis of temperature, if these southern forms arose in the cold -aters of the southern Appalachians or the hilly regions of the Piedmont. The only trniy serxonal species are Oreiaxithus up* 7-o 1, Baetisca rors Capsurus incertus, Hxa eia weew.. and probably the other species of Rexagenia, Ehemera siulans, heorella trilineata# and perhaps a few others*



ZOOGOGGAPHY


The topography of Florida has recently been described by Cooke (1939) in his ".:onery of Florida." He divides the state into five natural areas (see map 1) and these have been found to be closely correlated with differenoes in mayfly fauns. A discussion of the divisions of Florida can be found under the section on ecology.

Since mayflies are so limited ecologically* introduction into a nw area is subject to many obstacles. The many factors influencing drainage are the dominant elements directing the movement of primarily aquatic insects@ It has recently been suggested (Hubbell and Stubbs in Carr, 1940) that

1. An area in central Florida has persisted, in the form of large

islands or a group of keys, at least since the beginning of the

Pleistocene, and probably since Plicoene times.

2. The bridging of the gap to the mainland on one or more occasions

(perhaps first in the Pliocene), followed by renewed insular isolations

3. Final establishment of peninsular conditions during the Pleistocene.

4. More or loss extensive marginal submergenoes in late Pleistocene,











reducing much of the easteorn margin of tae peoninsula to a coastal

archipe lao.

5. Persistence of a salt-water barrier between Florida and the West

Indies at least since pro-Cenozoic times, and certainly throughoit the period of derivation of the modern biota of ";,e state.

It is unneessary to hypothesize or tloorizo that such Islands have

=- stea In order' to derive the ophemerid fauna. The wined stage of mayflies
-d T-e -et:.ods of dissemination of the insects weAld allow 1or rapid pexw'.ratlon of an area should ecological conditions beoue satisfactory for the maintenance of that species* On many of thc ;3"-an islands, conditions would not allow a very extensive development of mayflies because there are relatively few or no streams. It is not at all unlikely tkat when Florida was risi frcm the sea as isolated islands these islands were very similar to the Bahamas of today* If such col-ditionz persisted until l',nd connections vero formed, the i t-oduotion of mayflies into the region has been very recent, and, as is hypothesized below, thie fauna was derived mainly through the larger river drainages. Quite ikely, there were soue maflios inhabiting the Florida islaids, but they zust .av Loo i ond forms and species whioh could vrithatand vride variations in ecological conditions, Those speciec which may be endemic to Florida oould easly have arisen since the eztablilment of the -peninsula in the I'loistooene.

As Florida rose, the trceas draininG the southeastern portion of the

continent rere extended onto this new area carrying with them their northern faunae. In the Tnstern part of Florida, the Chatt.ahoochee, which drains the foothills of the Appalachians, and the Flint, whioh drains the Piedont of Georgia, came together to form the new Ap!Alohicela river. As the











Florida tributaries of this great stream began to erode back into the uplands, the conditions in their valleys tended to approach those of the more northern reaches of the river, and, as conditions in these tributaries became suitable, the mountain and piedmont species came to occupy all available habitats within the sall, rather rpaidly flowing but sand-bottcm streams*

The Apalachicola river drainage has without doubt been the main highway of ingress to Florida for the great majority of animals which require flowing water or hardwood forests. Rogers (1933) found that the ecological conditions existing in the Apalachicola drainage would admirably explain the distribution of many northern oraaeflies in Florida. Carr (1940) reports that the most extensive invasion of Florida by the northern element

is encountered in that portion of the panhandle which is drained by the Apalachicola rivers Hubbell (19361 354) states that "in this peculiar enviromment [the deep ravines of the Apalachicola region] a great many northern plants occur, evidently the remnants of a northern flora left as reliets from Pleistocene times in these deep, molst, cool ravines *.." It has also been noted that many northern plqnts reaeh their southernmost limits in these ravines and that many typically southern plants intermingle here with the northern species* Not only is this true of plants# but such has proven to be the case in the craneflies, the Odontap the Opilionids, the Orthoptera, the crayfish, the amphibiansand the reptiles.

Man of the species of Florida mayflies which have entered the state have spread out from the Apalachicola drainage and now occupy rather wide ranges in Florida, but there are certain forms which seem to be more or less confined to this region.










Not only has the Apalachicola served as an entry for the ephemerid

fauna, but also the Suwnnee and its tributaries may have brought in certain elements from the north such as Braehyperaus. Very likely, in addition, there has been some *bgration along the more easterly Coastal Plain region where the streams descend from the higher Piedmont. However, the forms which may have entered Florida over these or obher routes are few in comparison with those that have come in by way of the western path. Perhaps same species have entered by more than one route, moving in from the

east and from the vast and meeting to form a unified population in northern Florida.

Traver's recent paper on the Ephemeropteran fauna of Puerto Rico and infrequent records of other species from the West Indies show that those species of mayflies found in Florida have but few affinities with the insular fauna. No species are shared in oemon, and the genera which occur in both regions are very widely distributed. Although other species of insects have becoms established both in Florida and the West Indies# the mayflies have been unable to do this principally because of the eoologioal conditions of south Florida. The great majority of forms described from the islands are inhabitants of streams, particularly of mountain streams, and even if these mayflies were accidentally introduced into Florida, establishment would be impossible in the south. Ifby some rare chancs,a female which had been fertilized were carried to one of the permanently flowing sand bottom streams, it is barely possible that the species might gain a foothold, but this has apparently not occurred. The only Florida species that might be supposed to have been derived frm the West Indian fauna are Callibaetis floridanus and Caenis diminuta, but the former shows affinities with oontinen-











tal forms and the latter species is also probably of northern origin.

Hobbs (1940) has hypothesized that the orayfish now occurring in

Florida have been derived from migrants from the north or frm the west; his evidence indicates that the western element is much the larger. A few of the northern species of mayflies do appear to have swung westward around the southern Appalachians and thence into the Gulf Coastal Plain and Florida. In this sense only* sa any part of the Floridian fauna be considered of western origin*

Among the factors that may be used in explaining the present distribution of rheotropic mayflies in Florida, temperature may have exercised a considerable influence. In west-oentral peninsular Florida -- that is, in the Tampa region - the mean annual temperature of the air is 60 degrees Fk, while in the northwestern part of the state, where the principal part of the oontinental fauna is eonoentrated, the wrerage temperature is nearly ten degrees lower. Since temperatures in streams are less subject to variations than those in air# it is likely that average annual temperatures are more important to aquatic organisms than to terrestrial forms, for whioh the extremes of temperature are more likely to be the critical factors. It seems reasonable to suppose that the score or so of mayfly species oaon to peninsular Florida and the western part of the state must have relatively wide limits of temperature toleration. Those species having more restricted temperature toleration have remained confined to the northern and northwestern parts of the state.



Dispersal of mayflies

The two most important factors involved in the dissemination of may-











flies are wind and water. Of these, the latter, as far as the actual establishment of species is concerned, is by far the more important, for the imsture stages of all Ephemeroptera (except a very few brackish water species) require fresh water.

The ability to fly allows for the greatest amount of movement of

ephemerid species, although the adults are more or less confined to moist situations* The relatively short life span of the imagos must necessarily limit the flight range of the inseetsj however, the area occupied by a species can be extcaded somewhat through voluntary flight of the adults.

Such small, feeble insects as mayfly inagos are easily carried by the wind. This can be seen in the present distribution of the more diminutive generaj Caens# Baoeis, and otheres, which are found throughout the world. Lr. P. A. Glick, of the Uo So Bureau of Entomology, has made a thorough and very interesting study of the distribution of insects, spiders, and mites in the aire By means of traps suspended from the wings of an airplane, he collected many thousands of insects from various strata of the air. His results as far as the Ephemeroptera are concerned are listed below

Osenis Caenis sp. Hexagenia Ephmera Undetermined
M ,.I a sp. Bp. sp. (Oer 5000
.t, d a y_ _. . .. ..... ... . . . ... .. .
6000 f-.,

night__ _ _ _ _ __ _ _ _ _ __ _ _ _ _ __ _ _ _ _
400 ft.,oday ..




i000 ft.,day 1



ni ght , _ _ _ ..........











Caenis Caenis lexagenia Rphemera Undetermined
hilar s Bp* sp. p. p.

500 ftday I




The above figures illustrate the fact that mayflies can be carried to extreme heights, and& by means of horizontal air currents. doubtless to coriderable distances. Perhaps the greatest obstacles to be surmounted in aerial distribution at great heights are the short adult life and the necessity for the fertilized female to reach fresh water. Even when these two obstacles are overcome, the chance of the cological factors being satisfactory are but slight; current-loving species could hardly develop in a pond, and vice versa. The possiblility of distribution through wind currents at great heights, therefore# seems to be somewhat remote, but the chance nevertheless exists and must be considered.

From his study, Glick concluded that size, weight, and bouyancy of an insect bear directly upon the height to which it may be carried by air currents. He found that many species represented at high altitudes were small insects. Temperature was undoubtedly the most important factor regulating the numbers of insects to be found in the air at any given time, and he found that the optimum range was from 75 degrees to 79 degrees Fe, surface temperature*

Dr. Gliok points out that the intemsity of air currents is a great factor in the distribution and dispersal of insects. ibst insects ere taken at the lower altitudes when the surface wind velocity was from five to six miles per hour, and fewest when it was calm.

Winds at low altitudes are probably of importance in transporting adult insects from one region to another but their effdts are probably











local; however1 such local spreading continued over a lor period would eventually greatly increase the range of a species. A combiration of strong winds at low altitudes, flight, and proper ecological situations -would allow rapid distribution of mayflies.,

Within the continental area as a whole, stream piracy porbably has

acted$ and is acting, as one of the principal agents for the dispersal of mayflies. By this means, species may spread from one drainage system to another and from one region to another, gradually coming to occupy very wide ranges. This would be particularly important in the care of those species which as adults have but limited powers of flight and those which are relatively unable to withstand dessioation.

Flood conditions also operate as an influence in the spread of a

species during the immture stages. At the times of flood, stream velocity is greatly increased, and due to this increase rocks, logs, pebbles, and other objects to which the immatures cling are moved violently downstream. Doubtlessly, the greater portion of the animals on these objects are destroyed, but a few may survive to carry tI-e species far from its original home. From the lower reaches of the stream to which the nymphs have been carried, the species may extend its range into new drainages by the flight of the winged stages*

It is barely possible that wading birds might play a part in transporting myfly nymphs from one body of water to another* Many water dwelling organisms have been transported suooessfully on the le:-s of such birds and if the flights of the birds were short, necessitating only little time out of the water, it is possible that certain mayfly nymphs might survive a journey of this nature.











when the various possible distributional agencies are subjected to analysis, it can be seen that mayflies are principally disseminated by Plans of flight, by winds near the earth's surface, by floods, antd rarely by high air currents and stream piraoy*



CLIMATIC DIVISIONS OF FLORIDA


C. H. Merriam divided Florida into two regions which appear to be

useful in a general way for differentiating# ecologically, the flora and fauna of the Nearctic and Netropioal regionse He considered that part of Florida north of the Sto Lucie inlet on the east coast to Fort Myers on the west coast to be continuous with the Austral sone of the continental portion of North America, while the remainder of the state lying below this line was Netropicalo

P. P. Calvert, likewise$ has differentiated two zones in Florida# separated by differences in the mean annual temperature. Most of peninsular Florida falls into his Zone III#whioh has a mean annual temperature ranging from 88 degrees to 77 degrees Fo, while the western region is in his Zone II,with a temperature ranging from 59 degrees to 68 degrees F.

Rainfall in the Nearctic region of Florida is to some extent confined to a mid-summer rainy season, which in the southern tip of the state becomes

more distinct, In the northwestern area, although there is some dftarcation of a rainy season, the rainfall is more evenly distributed throughout the year. Byers (1930) has given in tabular form the average rainfall and temperature in various regions of the state in July and January, ,sd this shows fairly well the tendencies described above.

The distribution of mayflies in Florida is, for the most part, dependent on the presence of running water, although temperature probably also exercises
















































Fig. 1. - Normal annual temperature and precipitation, as campiled
from all available records to 1917 inclusive. Lines with numbers and the degree mark (0) at the end indicate temperature; shaded
portions indicate inches of precipitation during the year*
(From "The Climate of Florida" by Mitchell and Ensign)











no little influenoe. since Sreat areas of the state are characterized by swamp-like and sandy conditions and pine barrens with no development of streats, their Ephemeropteran fauna is extremely limited. This is partioularly true of that portion which lies at the southern tip of the state and commonly desinated the Neotropical region. The mayflies found here are not Neotropical in origin, but are true INearctio species distributed throughout Florida; in faot, Caenis diminuta is just as common throughout the eastern part of muoh of the Nearotie as in this unique, southern, biological area.



THE HABITATS OF FLORIDA MAYFLIbl



It is generally recognized that the mayfly population of a region

is intimately related to the aquatic conditions of that region. From the standpoints of both the ecological distribution of mayflies and physiography, Florida can be divided into five natural areas (see map I). The boundaries of these areas shown on the map are rather arbitrary. The aquatic conditions in the coastal lowlands overlap to a great extent those conditions found in the other areas, but these boundaries are useful in delimiting in a broad way the fresh water situations as they oocur in Florida.

The coastal lowlands almost everywhere lies less than one hundred feet above sea level; the height above sea level of the other regions varies from one hundred to about three hundred feet. The drainage of these various subdivisions of the state is closely linked with the topography.

The coastal lowlands is a swampy and marshy areainoluding, in its southern roaches, the great expanse of the Florida Everglades, and con-











tinuing uorthward into the muoklands of the Lake Okeechobee regions whioh in Lurn is continuous northward on the east and west wth the lowulands of the coast*

The oentral highlands may be divided into two areas. The southern half is entirely a lake region where almost every depression has its own pond or lake the northern part of this division not only includes lakes ponds# but there are also numerous surface as well as subterranean streams of all site&.

The Tallahassee hills and western highlands are rolling areas composed of rod-olay hills, well drained by many small streams, The Marianna lowlands, on the other hard, is made up for the most part of flatwoods, swampy areas, and rolling sandy hills covered by pine forests with few permanently flowing streams.

;everal large rivers arising in Alabama dnd Georgia flow through northwestern Florida and empty into the Gulf of Mexico. In the east, the large St. Johns river flows north along the border of the central highlands and the coastal lowlands*



LE.aiRiUFTIiA'o UF'EABliATS

Streams

Intermittent Creeks

In Florida, there are relatively few intermittent streams. These few are, for the moat part, merely connecting canals between awwmpA, ponds or other bodies of v'ater the level of which fluctuates continually according to the amount of precipitation* As far as mayflies are concerned, they are rather poor situations, and only the very tolerant Callibaetis and











Caenis nymphs can withstand the alternating conditions in the creeks produced by the continual changes in level of the bodies of water connected by the intermittent streams. Vegetation is usually abundant, but it is not of the type found in constantly flowing waters. Also, the drying of parts of the canal bed produces conditions whioh the stream inhabiting mayfly nymphs cannot for long endure, and even if, by chance, a species should become established during the period of flow, the cessation of this flow would bring about the death of the immatures.


Permanent Creeks


Permanently flowing streams are the most important of the mayfly

habitats in Florida. The creeks of this area may be divided arbitrarily into the following categoriest

(1) Sand-bottcm creeks with little vegetation* (2) Sand.bottom creeks ohoksd with vegetation .

(3) bilt-bottam creeks with little vegetation.

(4) 6ilt-bottom creeks choked with vegetation.

(1) Sand-bottom creeks with little vegetation: These are small, shallow, gently flowing streams with sandy beds* The creeks vary frm as little as one foot to forty feet in width, and in depth from a couple of inches to as zuoh as five feet. The bottom is composed of loose, rolling sand which builds up, in mid-stream, into small ridges behind whioh small masses of debris accumulate. Large rooks almost never occur in Florida streams, but pebbles nay be found imbedded in gravelly riffles where the water becomes quite shallow ihere are occasional pools, but they are not a conspicuous element of the streamso The pools are usually small, quiet areas near the











banks or at curves. Debris accumulates to a rather marked degree in some of the streams, almost any obstacle formi. a nucleus for the aecunulation of ueh 1ef drift, sticks, etc. Tree trunks frequently fon dams and give rise to riffles, while the tangle or branches and twigs provides a network in which much detritus becomes entangled. Silt accumulates near the shore and in places may produce rather thick deposits, in some streams even forming a layer more than two feet in thickness; however, for the most part, the silt deposits in the sand-bottom streams are sparse and of little consequence. Ne&r shore, leaf drift becomes a fairly important habitat, for many insects are harbored in this material, and in the almost stagnant shore pools the leaf debris may be several layera thick, interspersed with silt. The flow of water in the sand-bottom streams is never rapid in the sense in which a northern stream is said to be rapid; rather, the flow is gentle with the surface seldom breaking. Most of these strecaris are circun-neutral to slight. ly acid, but some may be pronouncedly acidic. Nearly all of them have tinted waters which vary in shades from almost colorless to a strong tea color according to the area drained and to the amount of rainfall* Most of the streams drain flatwoods, hammock lands, or swampy areas, and are fed bj springs or diffuse seepage areas. Vegetation is almost completely absent from the streams except for a few scattered Orontiun plants and an occasional olump of Persicaria near the qiAet shore zone; however, these plants are not particularly important from the standpoint of furnishing habitats for mayflies,

(2) ,and-bottoa creeks choked with vegetation: This sort of stream occurs mostly in the northwestern part of Florida beyond the Apalachicola river. The beds of the creeks are composed of fairly loose sand, but instead of











bein7 almost bare, ac in the type of stream mentioned above, they are covered with dense growths of Vallisneria, Sagittaria, and Potamopeton and these plants in turn are thickly covered with algae. There may be some debris collected in the slower areas near shore, but in mid-stream the vegetation is swept quite clean, although an occasional partially submerged log may lie among the plants. These streams are usually not much more nor less than twenty feet across and may be as much as five feet in depth at the center. In their deeper parts, the vegetation tends to disappear, and ma., be entirely absent from exceptionally deep stretches. The rate of flow is moderate, but seldom strong enough to cause any marked disturbance of the water surface. For the most part, the creeks drain scrub lands and high pine and hammock country, and the mter is much lighter in color than that of the streams described under (1); however, the water is usually definitely acidie, with a pH approximating 6.0. Silt deposits are not as pronounced in these streams as in those of class (1), and debris along the shore is likewise loses in quantity.

(3) Silt-bottom creeks with little vegetation: Silt-bottom streams are rather common in the northern part of the central highlands of Florida. The stream bottom is covered with a layer of silt overlying the sand and varying from a few inches to several feet In depth. The rate of flow is comparatively slower than that of the sand-bottom streams, but is is steady and quite perceptible. The water is definitely acidic and usually rater strongly tinted, often approaching a strong coffee color. The silt bottomr is frequently overlain by layers of leaves and strewn with much other debris, but there are few cr no plants in the stream proper. Near shore Persioaria and various sedges and grasses may be presents but they











are not espeoially abundant, This type of creek Kvera;:es about t wer-ty feet in wiedth and frcm a few inches to three feet in depth.

(4) silt-bottom creeks choked witth vegetation: These streans are not particularly common in Florida, and are confined mostly to t,-e :frti.western part of the state. The streams ere shallow, one to three feet 4n depth, but they may be quite wide and very meandering in their courses, and are sometimes braided. The vegetation is quite dense, and nay include plants which are characteristic of more slowly flowing or even stagnant water, such as Isnardia, Persioaria, and Pontederia. Other plants also found In the course of the stream include Vallisneria, Potamegeton, and Sagittaria as well as afmy algae. The silt in the streams is -very loose and maybe as much as three to four feet in thickness, This material is soft, fluffy and somwhat sticky, and at the slightest disturbance stirs up and clouds the water. There is usually a broad flood plain, and during i,- water the streams spread out widely over it until all vegetation is completely submorged (except larger bushaes and trees). There is a constant fltx of charnels cue to this flooding. In the shallover zones, the rate of flow of the water is negligible and during a rather sewlre cold spell, I noticed that the surface of one of the strewas was frozen over in the shallotv zoies.


Rivers


(1) ;ta7nant rivers: c..ta."ian t rivers are, for the most part, confined to the southern portion of the ?loridian peninsula, and -lany of them have been dredged witI .in the last fo,7 years to serve as crairae canals for the Everglades. These rivers are not, -triotly speaking, stagnant but the flw is so slight that only those rheotropie organiams which are very tolerant











to stagnation can exist in these waters. The Miami river furnishes an ideal example et such a waterwuy, bibil the drainage plans were carried out the 1iiami river was, in places, a shallow, moderate to swiftly flowing s&revz cutting through the limestone wiiicki forms the bedrock for south Florida. Charles B. Cory in Lis book "hunting and Fishing in Florida" describes and illustrates the iami river as it was in 1895, and paints a picture whioh certainly diiTers enormously from the present state: "The kiiami river, which runs from the Everglades into Biscayne Bay, is probably the on-y river in ilorida otioh has a fall or rapid worthy of the name. For about a tialif a mile at the head of this stream there is considerable fall. At this point the river is shallow aid not navigable for boats, a&d aias a very rapid current, in which 'Cavalila' hippu(r) are numerous and may be taken with an artificial fly." Dredging has completely

eliminated all rapids from the river and flow is not perceptible, even during the rainy season. The salt water of Biscayne Bay backs up into the river anZ produces a brackish codition some distance frmn thle mouth of the canal.

These stagnant rivers have fairly heavy growths of aquatic vegetation near their sanores, but they become deep rapidly and in the deep regions the plants are quite limited. The rivers vary from one hundred to two hundred feet in width in the widest places, and in depth usually range from fifteen to twenty feet. seie of the rivers do show a pronounced flow during the rainy mason and may even be subject to floods, but since the digging of t-ie drainage onals, thlis is the exception rather than the rule. There is very little depoust of silt in these streams and the bottom is mostly bare ( yrets-ree.
()Slowly - lowing.,deep rivers; This category includes nearly all of the











larger riveru of Florida such as the Suwaimee !id te ApclachihUla. These strems are lar-e and deep, and Ora3n vor; e;-tons'e areas; the "uvmnnee drins the 'kfenokbe 'wamp and the ipalachic.la aj' 7es in t .e foothills of the p"alachans and thce ?iedmont of Georgia and Alabama. The larger rivers have cont intuous flow, and durlni. or cessive rains tie Spread cub over their flood plains. In these lar.e rivers, vegetation is limited and occurs principally near the shores in protected places where the current is slow. This vegetation is more oharacteristio of standing water than of streans. There may be sBoe rocks near shore iAn the shallow rater, and silt may be deposited An protected areas, but for the most part the bottoms are :or clay or limerook. The Atpalaohioola river is frequently very muddy due to the heavy burden of silt it brings down fraa the Georgian highlands. The )umnee is miuoh bearer, althouga the water may be stroyigly colored b', the various organic acids oomin from the swam ps drained by the river. The At, John's river has a much slower current than the other two streams just named, and north of Lake George the flow is slight and affected by the tides. This river has masses of miter hyacinths growing at the shore, and conditions are not very different fra those found in the lakes of the cetral highlands ,nhich sUpport growths of this plait. 1fearer its head ",raters, there is Vallisneria and Sagittaria in the stream and the flow is more noticeable. %uoh of the water of the St. Johns is of swamp origin, and t}is is reflected in -e bromvnsah coloration of the stremmu

(s) L-arger calcareous streams: This eategory includes streams vriich are#

Scxural, ar:aller than tlose Included abo-e and wich arc definitely basic n their reaotionso lhost of the-se streaks arise from springs and for. sRall rivers such as Silver river, w-akulla river, the Santa Fe river, etc.











They are clear, oool, and moderately flowing with rather dense growths of vegetation in the stream proper. Vegetation is composed chiefly of Vallisneria, Sagittaria, Nais, Isnardia, mosses, many algae, ete which in the shallower zones form dense mats oompletely covering the floor of the stream* The water may be colorless if the source is confined to springs, but if swamp waters also contribute to the stream the water may be tinged with brown. Many of these rivers have send-bottos, and there may be thick deposits of silt in the quieter shallow zones. Leaf drift and other debris becomes entangled in fallen trees and other catoh-alls, and such debris forms an important habitat for many mayflies and other organisms. In some of the rivers, there are outcrops of limestone, and in the Santa Fe river, specifically, there are many loos* rooks which are of great importance as habitats for aquatic organisms* The depth of these streams varies from three feet to twenty feet or more, the width from seventy-five to three hundred feet. Faunistioally, this type of stream is the richest found within the boundaries of Florida, both in number of individuals and in species* Carr (1940s 25) states that "Optimm conditions [for fluvial organisms] apparently exist in those rivers which run over ledges of exposed limestone, or which receive most of their water from calcareous springs."


Ditches and Puddles


(1) Roadside ditchesa These are extremely rich situations for aquatic organisms if there is permanently standing water in theme The ditches are quite varied in appearance but the fauna is fairly constant. In some of them, there are dense growths of Pontederia which is the predominant

plant. The water is shallow in the zone of piokrol weed, but may become











much deeper beyorid this regions in the deeper parts other vegetation which can stand greater degrees of submergence is present. The bottom of the ditches is usually covered with grasses and may have heavy growths of Globifera umbrosas Isnardia, and Persicaria. Algae form dense mats in some of the ditches along with Utrioularia, Ceratophylluu, Potamogeton, and *yriophyllum. At times the water may become very warm, in fact hot, during the simmer in winter it is often quite cold, with ice sometimes forming over the surfaoe* The water in these ditches in usually acid but may be basil the lowest pH recorded was slightly above 4.0. The depth of the water varies from a few inches to as much as four or five feet, and the width of the ditch (that part containing the water) may be from one to fifteen or more feet.

(2) Puddless In this category are placed those small and transitory bodies of water left by the retreat of a stream or formed by heavy rains. There is no, or very little# aquatic vegetation in such puddles, and it is only by remote chance that organisms are found in thea. Such animals are stream relicts which' soon perish# for the puddles dry up rapidly during dry weather; however, I have found mayflies in such places and for that reason I am including this situstion. In some of the puddles there may be several layers of leaf debris. Silt accumulates between the leaves and algae begin to growcontinuing as long as the water remains.


Ponds


The ponds of Florida may be divided into several types, but nearly all of them share one characteristic in common -- they seldom have streams draining into or from the**.










(1) Sink-hole ponds: These ponds are formed by the dissolution of underlying limestone. Rainwater, percolating downward to the water table, diesolves vertical chimneys in the limerook into whioh the surface cover may collapse gradually or suddenly producing a steep-walled, open sink. Where the cover is thicker or less compact a saucer-shaped or funnel-shaped depression may result. There are many of these ponds of sink-hole origin in Florida, and in particular around the Gainesville area. Some of them are dry but the great majority have standing water, which maintains a fairly constant level because the water table is high enough to supply the ponds continually. The sides of the ponds both above and below the water level are steep and the zone of rooted aquatic vegetation is very limited. The sides of the sink-holes above the water are usually covered with vegetation which extends from the qde of the water up to the rim of the depression. In many of the sink holes a narrow sand beach may be formed where the slope of the sides levels off, but the shore zone extendint into the water from this beach is very narrows and the drop to deep water rapid. There are two chief types of sink-hole ponds:

(a) Ponds with the surface free of VOeAtations This is one of the oommon types of sink-hole ponds encountered in peninsular Florida.

The margin of the pond has a fairly rich growth of both submergent and

emergent vegetation, which extends outward to the region where the dropoff occurs* This is composed principally of Saocrolegis striata, Perseearia, M7aoaa fluvitalis, Junous., and some Myh as well as numerous species of algae. This sudden drop to deeper water begins at a depth

of about four and extends to a depth of about ten feet; thence the drop

continues more gradually to about twenty feet. In many of the ponds











there may be deeper holes such as that found in Lals Mize, discussed by Harkness (1941), which over a very small area reaches a depth of nearly eighty feet. In the shallower portions the bottom is sandy and covered with patchy growths of Utrioulariao There are only small deposits of silt in the shallower zones, but in the very'deepest parts the bottom may be thickly covered with black# dense silt, in which practically anaerobic conditions exist and in which living organisms are almost entirely absent. The water varies from colorless to a strong tea color, depending on the type of region drained by the pond* Many of the ponds are rather turbid, and this turbidity combined with strongly tingoed water allows little penetration of light to the deeper parts. The water varies in reaction from pond to pond, being aeidio, oiro ineutral, or slightly basic*

(b) Sink-hole ponds with the surface covered with vegetation: There are two principal varieties of this pond type -- (1) those covered with water hyacinths (Piaropus orassipes)j (2) those covered with duckweed (Lemna minor), mud-marys (Bruneria punotata), Azolla caroliniama, Salvinia. aurioulata eta,

The first variety of pond may have a marginal ring of open water with t he water hyacinths concentrated over most of the remaining area, or the entire surface may be covered with these plants* If there is some open water, submergent vegetation may take root and becme fairly well established, but for the most part the water hyacinths are the only plants of any importance in the ponds* The duckweed covered ponds seldom have any submergent vegetation growing in them, for the entire surface is covered with a single layer of these plants cutting o~f











light from any vegetation which might attempt growth on the pond bottoms

'4hen there is any wind the duck weed piles up and leaves clear areas

on the water surface, but as soon as the wind dies down, the plants

again spread evenly over the surfaus. Amphipods (11ya!lela azteca)

are exceedingly nuerous in these ponds living among the duckweed, but

bottom organisms are scarce probably because of the small amount of

oxygen* The bottom of this type of pond has rather thick acoumulations

of black silt, heavily loaded 4,%th hydrogen sulphide, covering the

sandy bottom, and almost anaerobic conditions exist there. The sinkhole ponds are usually about one hundred to three hundred feet in diameter, and are mostly round in shape. Some of the larger ponds

are formed by the coalition of two or more sink-holes.

(2) Fluctuwting ponds These constitute one of the more frequently encountered types of Florida ponds. Water fills shallow basins -- some mere depressions in the original sea-laid sands, the majority produced by solution of underlying limestone or by wind action. The level of the water in these hollows varies with the amount of rain and surface runoff. There is a great fluctuation in the area occupied by the water because a slight rise or fall causes marked spread or retreat of the margins, but the depth usually does not change greatly because of the shallowness of the pond. True aquatic vegetation follows the rise and fall of the water to some extent, but it is chiefly confined to the region below the more permanent water levels "These periodic and sporadic fluctuations [due to the rainfall] prevent the development of any permanent vegetation within the broad tone of fluctuations As the water recedes in the dry season, it leaves a belt of saturated earth in which some grasses and sedges spring up among mats of stranded algae and











other aquatic vegetation ooo. The permanent water is usually filled with submerged, floating, and emergent aquatic plants and may support extensive floating mats of green algae" (Rogers, 1933)o The vegetation includes many true aquatics such as Pontederia, Utrioularia? Persicaria, Globifera, T t, c. as well as Hydrocotyl, maiden-can (Juneus), and other semiaquatios. Many of the ponds have coverings of Castalia, and some support !",mphaea, but very few are covered with water hyaoinths. Plants are not confined to a shore zone, as in the sink-hole ponds, but may extend much further out and in some instances may ompletely penetrate the ponds* The bottom of the fluctuating ponds is mucky, but the layer of silt is not deep. The water is subject to rapid changes in temperature and is much influenced by external weather conditions* There is normally a slight tint to the water and it is usually acidic.

(3) Temorary woods ponds, These ponds are formed in depressions in hemmooks and are of a more or less temporary nature; howver, the vegetation present is sueh as to indicate its habitual occupation of the depression. In these ponds and around their margins are frequently found blaok-g= (Uyssa biflora), button bush (Cephalsanthus occidetalis), willow (Salix niger), bladderworts (Utrioularia sp.), etc*, and if the water remains for a sufficient length of time other more succulent vegetation will become established. iater the water has been standing in the depression long enough to allow growths of algae many of the usual pond aulmals begin to migrate to a"d become established in the pond.

(4) Soradic ponds: The sporadic ponds are of a rather temporary nature, and during the dry seasons may completely disappear not to reap"ea for same time, perhaps they may even disappear permanently* If they remain for











a time, vegetation and animals may become established, but frequently they dry up in such a short period that such does not take place. The ponds are shallow ad may be large or small depending on tho depression and the

drainage of the region*

(5) Jerome sinks Because of the unusualness of this situation, it deserves special classification* A descripiton of the sink is included in the discussion of the ecology of Choroterpes hubbelli on page 46


lAkes


According to the recent investigations of Mr* So Stubbs of the Florida State Geological Survey, nearly all lakes in Florida are the result of solution of underlying limestonej however, such lakes as Lake Okeechobee seem rather to occupy basins which are natural depressions in the surface formed as the land rose during the last geologic period. "Mazy Florida lake basins are simple sinks that have always been tributary to the groundwater supply and never have had a surface outlet* Others at one time or another formed part of the surfaQ.e drainage and therefore were connected with the river system. Their history is complicated, for the fluctuations of sea level and the consequent fall or rise of the water table gave opportunity alternately to deepen the basin or to flood them. Some of them appear to have been estuaries during higher sta#es of the sea, for the sand-covered terraces around them stand within the limits of altitude of the coastal terraces." (Cooke, 1939a 100-101). Cooks concludes that Lake Okeechobee,, Lake Istokpogas Lake Kissim:.iee, Crescent Lake, Lake George# and others originated as hollows in the sea bottom.

(1) Sand-bottom lakes. By far the commonest type of lake found in Florida,











the sand-bottom lakos form the most conspicuous bodies of water in the central highlands* There are literally thousands of these lakes in this region and they are particularly numerous in Lake county. The lakes vary in size from a quarter of a mile to nine or ten miles in width, but the depth is not correspondingly great and most of them are shallow, not more than forty or forty-five feet at their deepest holes* There is little vegetation except at the margin# and this is chiefly Sacrolepis striata, Utrioula;tia, and algae. Wave action is slight but it is probably sufficient to prevent the growth of more usual aquatic vegetation along the sandy shore. The 3aoo'lePis extends out into the lakes to a depth of five or six feet and beyond this zone vegetation is limited to submergent plants such ans Utriculara. which lies on the sand bottom as far out as there is sufficient light penetration for normal photosynthetlo processes to take place* In this region, some silt is intermingled with the sand, but much ol" the sand is bare. Beyond a depth of about twenty feet, silt accumulates and covers the bottom sand with a layer several inches deep; with increase in the depth of the lake there is a direct increase in the amount of silt., In the very deep parts of the lakess the silt may reach a depth of a foot or more, and in this region it is a very thick, black, fine# and oozy mud in which almost no organisams live. Along the shore some debris collects, but is not abundant; this debris forms an habitat for mary insects which are normally found in streams* Probably the vve action in this region is sufficient to oxygenate the water and produce conditions which simulate those of moderately flowing streams. The water of the lakes varies from very clear to strongly tea colored and the turbidity is also very variable according to the label. Lost of the lakes are ciroun-neutral, ranging not











much more than .5 on either side of a pH of 7.0.

(2) Silt-bottom lakes: This type of lake is well exemplified by Lake Newnan near Gainesville. The lake is qidte larga, .n,, about ten miles in len.h and about three miles wide. It is bordered by a ring of cypress which extends from dry land into the vater. Also margining the lake, water hyacinths form dense growths between the bases of the cypress trees and extend out into the lake as far as there is a protected zone. 4ith every shift in the direction of the wind, water hyacinth plants break free and float across the lake, pushed onward by the winds Frequently, during a period of sustained moderate winds, the lake is dotted with numerous floating "rafts" of water hyaoinths; eventually these plants pile up along one shore until the wi;A a&ain changes and sends them sailing back to the opposite side* The continual rain of dead water hyacinths onto the bottom of the lake has given rise to a thick layer of loose fluffy silt which completely covers the bottom to a depth of two or more feet* "Imost no living organismas can be found in these bottom deposits for conditions are not conducive to life. The lake is shallow; -n the middle it is not much more than ten feet -n depth, and over most of its area it is shallower than this* The vater has a definite brownish tinge and is rather turbide

Numerous other lakes in the central highlands also belong in this same category. Orange lake, one of the larger lakes of this region, is similar to Lake Newman in its type of bottom, but is is deeper, has much rooted vegetation in the form of water bonnets, and is somewhat exceptional in having numerous floatin& islands of vegetation. Some of these floating islands are large enough to support trees, but the great majority are small clumps of vegetation which float about, changing location with each change











in direction of tre wind,

"These lakes show great variations in their aquatic vegetationj in many, the succession is directly toward swamp conditions with extensive development of cypress along the muddy shores; in others there is a distinct developmedb and zonation of marsh vegetation before the shallow water is invaded by cypress or hardvood swamps." (Rogers, 1933).

(3) Lisappeari lakes! Certain large lakes in the northern part of Florida go dry during periods of drought. Lake lamonia near Tallahassee is an ideal example of a disappearing lake, and went completely dry in 1938. There is one near Lake City whioh is said to go dry periodically, "once every seven years." These lakes are ihallow, and im most respects are similar to the silt-bottm lakes in having an abundant growth of water hyacinths and a ring of cypress bordering theme Although at their maximm extent the diaaj.pearing lakes are fairly large, they vary greatly in size with seascial fluctuation in depth.


Marshes


(1) arshes are very common in peninsular Florida, particularly in the lower regions. They may be very limited in extent or quite large according to the size of the origLnal basin* Many ponds and lakes have become converted inLo marshes, and many others are in the process of transition. 1"he wter is shallow and vegetation extends throughout, growing very profusely. The most predominant plants are emergent and include oat tail,

piokrel weed, rmiden cane, saw grase, water lillies, sartweed, and various zrassese Submergent plants are quite prominent including Isnardia, Globif L.yriophyllij, and many algae. The water is rather wLtrm during the











summer and may freeze over during prolonged periods of cold. The filling of lake and pond basins is rapid and the great amount of decaying vegetation quickly builds up deposits of pea.t, whick finally re .lacez tia water of the marshes. The level of the water is subject to great fluctuations according to the amount of rainfall* and at tiaaes the marshes go completely dry., but over the greater part of the year, water remain in them, The marshes are definitely acidic, some 1-aving a p1l ranging below 3.*; but this condition is local, and at different points in the sane marsh the p.1 may range frcm 3* to 6.0 or 1iher, The organisms found in the marshes are not essentially different from those occutxying similar habitats in ponds and along lake marains, for conditions in these marshes are very Piach like those of the pond margins. The principal differences lie in the facts that emergent vegetation occurs bhroughout the w-ter rather than being confined to a s::ore zone, and in shallowness, the marshes being not much more than three feet deep at their deepest point.

(2) Another type of marsh found in the central part of Florida is very similar to the above except that vegetation is principally Persicaria and saw grass (ariscus sicensis), with the Pontederia much more limited in extent and with no Ny&nhaea present however, the organisms inhabiting these marshes are identical with those found in the other types.

(3) !be Ler !aes The lverglades are so distinctive that they require discussion under a special category. "The Everglades occupy a nearly level plain, which slopes from 15 feet above sea level at the south shore of Lake Okeechobee to sea level at the tip of the Peninsula, a distance of more than

one hundred miles. One the west the 7verglades merge into the Big Cypress Swamp, which presumably is a few feet higher. On the south and southwest











tae .Verglades are bounded by mangrove swuppp, which separate tnem from the open waters of Florida Bay and the Gulf of Loxioo...

"The Everglades, as the name implies, are open grassy meadows. Hers and there clumps of trees lend variety to the landscape...
"Ine Everglades differ from most swap. qnd boggy places in the scarcity of trees and in their lack of ordinary mud and clays The entire Everglades are underlain by nard limestone$ which is cushioned in the lower# generally flooded parts by deposits of peat..... ihere peat is absenit, bare limestone shows at the surface*" (Coake# 19391 5546).

Since drainage ditches have been put through the Everglades# the land, during the dry periods, becomes very liable to burning and much of the peat has been destroyed in the last few years* During the rainy season much of the zverglades is covered to a depth of two or three feet by the water which overflows from the drainage canals. 6hen this flooding occurs, the normal biocenoses of the canals are no longer confined to these channels but spread uniformly over the inundated areas; however, the spread is thin compared with the concentration of organisms within the canals themselves. Only pond, mamp, and stagnant wtter animals can maintain themselves in this environment, and the mayflies associated with this region, Callibaetis floridanus and Caenis diminuta, are typical pond and swamp inhabitants Which are found throughout Florida*

Saw grass is the predominant vegetation and grows profusely throughout the rilarshe The lack of shade trees allows the water to become very wm~ outside the canals, but in the canals themselves it is several degrees cooler There is little submerGent vegetation where the overflowing water has spread over the glades, but after it has stood for some ti.e algae become noticeable*











swamps


(1) Cy ss swamps: Cypress swamps are very numerous in Florida, and some of these, such as the Big Cypress -swamp, occupy huge areas. The cypress swamps are foned in shallow depressions in flatwoods regions, and over moat of the year have standing water in theme Not only does cypress occur in them but black gun is also very acnno Herbaoeous vegetation is, howevert limited though there may be olunps of Persioaria. Utricularia, and some sphagnum along with masses of algae. The water is usually tinted by humis aids, and its reaction is definitely acidic. Depth of water varies considerably# but is seldom over three or four feet.

(2) Bysheadsa Bayheads are very similar to cypress swamps, but the vegetation in much denser, and the bayheads usually foe the headwaters of smafl creeks. The plants consist mostly of small trees and shrubs and also include some cypress. The other trees are principally sweet bay, black gun, wax myrtle, red maples loblolly bay, titi, Virginia willowp and dahoon holly. The growth of the shrubs is so dense as to be almost impenetrable in places. Water stands in the depressions for the major part of the year, and it is only during the very driest seasons that it entirely disappears from the bayheadse


springs


"Most of the large springs of Florida are artesian. The water flowing from them rises through deep, generally vertical holes in limestone, some of which holes extend more than one hundred feet below sea level. At the bottcm..these holes open into caverns, presumably nearly horizontal, through which flow underground rivers....











"Tie cavity through i0,ich water ascends to an artesian spring is
generally a former sink in which the direction of uotion of the water has been reversed by the rise o' the urater taLlo. if t I w4.ter table were to fall below the mouth of the cavity, the spring would cease to flow and would revert to the form of a sink, provided the tubular cavity leading to the spring does not penetrate an imprevious stratus, which might confine the wuter below it under pressure." (Cooke, 1939: 88-8.9).

The runs of some of the larger springs have been disoussed under larger calcareous streams, but the majority of tim, are much smaller. Vegetation is very dense just below the exit of the spring, but around the spring itself there is nothing but bare eazd, Imaediately beyond the periplry of tUe boil Chara, Xriophllum, Ceratophyllu, iVallineria, Sagittaria, Isnardia, etc. bcoms very abundant. The surface of the vegetation close to the spring is usually cowered with a coating of caltiau carbonate deposited from the water as the bicarbonate exposed to the air oanges to the sarbonate. Uxygon is low, and this is reflected in the mall populations of truly aquatic inseots in this region; however snails of' the genus Goniobasis are exceedingly numerous on the vegetation, and iApulluria occurs abundantly on the bottom sands. approximately a quarter of a mile below the Lead of the springs a more abundant insect fauna become noticeable and in this region the plants are quite free of the calci.; carbonate* The w.ter of the springs is crystal olea, cool, and definitely alkaline.











AC KNOWLEDGEMENT S


I wish to express my sincere appreciation to the many people who

have helped in one way or another in this study. In particular, I would like to thank Professor To H. Hubbell for continual encouragement in this work# for mazy helpful criticisms# and for examination of the manusoript, Professor J. So Rogers whose aid, encouragement, and advice have been invaluable; Dr. H. He Hobbs for numerous suggestions and discussions of the problem, for aid in collecting, and help in drawing. Various other members of the faculty of the Department of Biology of the University of Florida have also offered many suggestions and participated in discussions which have been very eluoidatingj I would like to extend my thanks to Professors Co F. Byers, He B. Sherman, We J. K. Harkness, Drso H. K. Wallace, and As F. Carrs In addition, I wish to acknowledge the helpful suggestions, criticisms, and disoussions of my fellow graduate students at the University of Florida*

To the many friends who have collected mayflies for me, I take this

means of expressing my gratitude. In the locality records of each species, the oollector's name is placed in parentheses. In particular, Mr. F. N. Youn, Mr# L, J Marohand. and Mrs We )4 McLane have assiduously collected all ephemerids with which by chance or otherwise they have happened to come in contact. Those persons who have collected numerous specimens have been referred to by initial only, as follows# Jo S. R, -- Js Speed Rogers

He He e -- He He Hobbs

Lo Jo M, -- L. Jo Marchand

F. No Yo - Fo N. Young

Lo Be -- L. Berner











In addition, the names of all persons who have apoanpanied me in the field have been included as collectors# even though at times they may have been unable to help me with the taking of mayflies*

And finally. I wish to thank Dr. P. P Ids, University of Toronto# Dr. H. T. Spieth, College of the City of New York* and Dr. Jo Re Traver, Massahusetts State College, for examining man of the Florida speoies of mayflieso































A KEY TO THE MAYFLIES OF FLORIDA














A KEY TO T"Ir MAYFLIES OF FLORILA

ADULTS


1 Veins CuA and MP strongly divergent at base; MP2 strongly bent

toward CuA basally (see fig. 1). Hind tarsi four segmented* Ephenieridae (2)

1' Veins CuA and MP only slightly divergent at base; MP2 more nearly

symmetrical (see fig. 2). Hind tarsi four or five segmented.

(7)
2 (1) Basal costal cross veins weak. Costal angulation of metathoracia

wings approximately ninety degrees (see fig. 3). Median oarina

on prostermm.

(Necepheerina.) "Oreianthus sp. !!o. 1" Traver 2' Basal costal cross veins normally developed (see fig. 1). Costal

angulation of metathoraoic wings greater than ninety degrees (see

fig* 4). No median carina on prosternum.

(3)


3 (2') Marginal veinlets present (see fig. 1).


3 Marginal veinlets absent.

(Campsurinae) Campaurus incertus

4 (3) Cross veins somewhat crowded at and below bulls (see fig. 5)j

wings with pattern of dark spots. Tails three, of equal length.

EpheEmra simulans

4' Cross veins not crowded at bulla; wings with no such distinct

pattern of dark spots (see fig. 1). Tails two (plus vestigial

middle one).














Hexagonia (5)
5 (4t) Penes slender, somewhat beak-shaped (see fig. 6); abdomen banded

longitudinally with dark and light areas.

Hexagenia bilineata

5' Penes more or less hook-like (see fig. 7); abdominal markings

not as above.
(6)

6 (5') Body of female canary yellow; dark abdominal markings limited;

fore wing 24-28 mm. Male prominently marked; hind wing with wide

purplish-brown border, large dark spots near middle; many cross veins of fore wings widely margined with purplish-brown. Distal

segment of middle and hind legs dark on under side. (see figs 7).

aagenia weew

6' Body of female and male heavily marked with purplish brown. Hind

wing with or without wide purplish-brown border and brownish spots in middle; if brown border and blackish spots present, outer segment only of middle and hind legs dark on underside.

(7)

7 (6') Hind wing without prominent purplish-brown border and no large

blackish spots (see fig. 4). Outer segment of middle and hind legs with dark markings on underside. Female yellowish with a tinge of

brown. Inhabits lakes.

Hexagenia lImnophila

7' Hind wing of male with prominent purplish-brown border and large

blackish spots many cross veins of fore wings widely margined with purplish brown. Outer segment only of middle and hind legs








i'~w











dark. Abdomen of female yellowish-white; prominently marked with

purplish-brown. Inhabits streams.

Heagenia orlando

8 (1') HIind tarsi with five freely movable segments. Venation not greatly

reduced; oubital intercalaries in two parallel pairs, long and

short alternately. Eyes of male simple. (see fig# 2).

eptageniidae (1-Leptageninae) Stenonema (9) 8' Hind tarsi with three or four freely movable segments., Cubital

interoalaries not as above. Venation sometimes .-reatly reduced

(see fig. 8). Eyes of male often divided.

Baetidae (11)

9 (8) Brown bar in fore wing uniting 2-4 oross veins in space between

R, and R2. Brown spot at tip of fore wing Just below R2 (see fig,

9). Penes with spines along lateral border (see fig. 10). 2ody

of male yellow; of female yellow, but if eggs present, abdomen is

brilliant orange.



9' Wing without brown bar. No brown spot at tip of fore wingy (see fig.

2). Penes without spines on lateral borders (see fig. ll). Both

sexes white.

(10)

10 (9') Dark spiracular spots present on abdomen. Tails narrowly annulate

with purplish brown at joints. Posteromedial portion of penes angulate (see fig. 11),

Stenonema smithas

10' Dark spiracular spots absent. Tails not banded. Posteromedial













portion of penes rounded (see fig. 12).

Stenonema exi guum,

11 (8') Hind wings absent. Fork of MA very deep; posterior margins

of wings ciliate; no marginal inLercalaries (see fig. 8). Eyes

of male simple, neither divided not grooved widely separatedo.

Casnime (12)

i1' Hind wings present or absent. Fork of MA in fore wing normal

or detached basally; morgin of wings ciliate or not; marginal

interoalaries present or absent in forewing (see fig. 14 and 15).

Eyes of male divided or simple in genera lacking hind wings*

(14)

12 (11) Prosternum twice as wide as its length; fore coxae widely

separated second antennal segment three times the length of

the basal segnent.

�BMhycerous maculatun

12' Frosternkm two to three times longer than broad; ooxae much

closer together; second segment of antennae not mLach more than

twice as long as basal se3rert. (see fig. 8)

Caenis (13)

13 (12') Ltigmatio dark streaks on posterior tergites only. Head pale.

Thorax light brown. Short fine black streak on dorsal edge of

each femur*

Caenis hilaris

13' Stigmatic streaks present on anterior tergites. Head dark shaded.

Thorax light brown. Hind femora with a dark apical band.

Caenis diminuta














14 (ii') A1 of fore vin~s end& in outer margin; no cubital interoalaries;

basal third of fore win,; and basal four-fifthe of hind wing suffused with orange-brown (see fig. 13). Eyes of male not

divided.

(Uaeticoinae) baetisoa rogersi 14' A1 of fore wing ends in hind margin; cubital interoalaries

present (see fig. 14). Syes of male divided, marked with a

distinct band, or simple.
(15)

15(14') MA2 and Ml2 of fore wings detached basally from their respective

eterns. (see fig* 16). Hind wings much reduced in size and

venation, or they may be entirely vmnting (see fig* 16). Eyes

of male turbinate.

Baetinae (2,1)

15' MA2 and ik-2 of fore wings normal, attached basally (see fig* 14);

or i2 may be detached basally, but this is paralleled with loss

of hind wings. Eyes of male not as above. If hind wings preent,

vei.ation of mletathoracic wings not greatly reduced (see fig. 17).
(16)

16 (15') Tails two.

(24)

16' Tails three,

(17)

17 (16') Two short intercalaries in fore wing between IMP and IT2 and

between LF2 and CuA. ,iale forceps with a single terminal segmenb (see figs. 14 and 18).


Ephemerellinae


(18)






UI











17' No true intercalaries in fore wing in position indicated above.

Male forceps with two short terminal se~ients (see figs. 19 and 20).

Leptophlebiinae (19).

18 (17) Hind wings absent. Forceps three-segmented; an ovoid selling

at base of secoid seo.ent on irner margin (see fig* 21).

j Tricorthodes albilineatus 18' Hind wings present. Forceps three-segmented, no mmelling on

second segment (see figs. 14 and 18).

Ephemerella trilineata

19 (17') Hind wings reduced in size and vonation; distinct costal angulation

half-way to apex (see fig. 22).

(20)

19' Hind wings larger. venation more prominent; no costal angulationj

costal margin slightly concave at middle (see fig. 23).

(22)

20 (19) Costal anoulation of metathoracic winG obtuse; no sag in fork

of MA of fore wing (see figs. 22 and 24). Penes long, simple,

without reflexes spur; forceps base of male undivided (see fig.

26). Subanal plate of female slightly emarginate.

Choroterpe s hubbelli,

20' Costal angulation of hind wings acute; a distinct sag evident

in fork of MA of fore wing (see figs. 19 and 26). Penes with

reflexed spurs; forceps base deeply cleft (see fig. 27). Apical

margin of subanal plate of female deeply cleft.

(21)

21 (20') Suboosta of hind wing ends in margin at outer side of costal































OW











angulation; two term nal segmentu of forceps snort, together

not one-fourth the length of preoeeding segment; reflexed

spur rubclavate at tip, (See figs. 19, 26, 27),

Ilabrophlebiodes brum ipennis

21# Ouboosta of hind r extends almost to ape.. of wings Two end

segments of forceps together equal in length to the preoeeding

segmento Reflexed spurs long and slender, not subelavate at

tip. (See fir. 28).

Habrophlebis. vibrans

22 (19') Iiddle tail shorter and weaker tlan laterals.

Blasturus intermedlue

22' Aiiddle tail approximately equal to laterals in length end thickness. Peries partially united (see fig. 29).

?araleptophlebia ( )

23 (22') iieflexed spur of penes curved, spatulate, reaohing to bottom

of cleft between penes; penes united for one-fourth their length,

long and tapering (see fig* 20). :.iddle abdominal segments of

male brown. Llackish rings on apical third of all femora, Wings

with a brownish tinge; stigmatic cross veins anastomosed.

Paraleptophlebia bradleyi

23t Reflexed spar of penes claw-shaped; penes united for one-half

their length (see fig. 29). Middle abdominal segments of male

predomaiLatly White. Femora without dark rings. Wings oolorless;,

stigmatic cross veins but little anastomosed. (See fig. 30).

Paraleptophlebia volitans

24 (16) CuI of fore wing consist of series of forking or sinuate vein-










I:i










lets attachin- CW. to hind margin. (See fig. 31).

(Siphloaurinae) Isonyqhia (25) 24' CuI two to four in number, free basally, not s. above (see fig.

32).

(12tretopinae) Siphloplecton spee0osum 25 (24) Venation almost colorless.

(26)

25' Verat ion dark.
I sonychia s.B

26 (25) Yore tibiae wolly dark.

Isonyohia perdido

W Yore tibiae pale in the middle and dark at each end.

IsonycKhia pietipes

27 (15) land wings present.

(28)

27' Hind wings absent.

(38)

28 (27) Fore wf:gs with numerous costal cross veins before the bulla;

in female, costal margin brownish (see fig. 33). Moderate number

of cross veins present iL hind wings.

Callibaetis (29) 28' Fore wixs without costal cross veins before the bulla (see

fig. 15). ITo cross veins in hind wings (seo fit. 16).

(31)

29 (28) d -- Intercalaries in mid-posterior margin of forewing occur

singly. Abdominal segments two - six whitish hyaline with




























.




Full Text
246
Walton county, Florida. (See rn'p ^
ECOLOGY Among the unexpected places in which hubbelli has appeared,
the most spectacular was Jerome Sink. This sink is located approximately
two miles north of Newberry in a perennially arid region. Drainage in
this part of Florida is subterranean; the nearest surface stream being
the Santa Fe River which is about twelve miles distant. Underlying the
Newberry region, there are many subsurface streams, but very few are ex
posed at the surface and, of those which are exposed, only a small por
tion of the water is in evidence. The opening to these subterranean
waters is usually a steep-sided sink hole, sometimes even well-like, the
sides of which may be covered with various types of ferns. Flow is not
evident in any which I have observed; however, the various underground
channels do seem to connect as indicated by the distribution of the white,
cave crayfish, Cambarus pallidus. The walls of Jerome Sink extend thirty
feet downwards to the surface of the water, and thence an unknown distance
to the bottom of the sink. The east wall, below the surface of the water,
is open probably connecting the sink water with the subterranean drainage.
Along the west shore of the sink, the bottom drops off rapidly, but there
is sufficient show to allow an accumulation of dead leaves and other
debris. It is here that Choroterpes nymphs occur along with Epiaeschina
heros, a dragonfly which Byers (1930 256) says "lives clinging to debris
caught in moving water;" other insects are rare, but Erimystax sp., one
of the small, stream-inhabiting minnows, is rather common* The water is
very clear and blue, presenting a picture of water which is certainly not
stagnant.
Very few species of mayflies inhabit the shores of sand-bottom lakes


107
graphic area occupied by smithae.
HABITSt Stenonema nymphs oan be identified at a glance among Florida
material their flattened bodies, broad, flat heads, and spreading legs
are characteristics shared by no other speoies in the state; however, the
habitude of the nymphs does not easily separate smithae from the other
Florida Stenonema. When morphology and ooloration are employed, the three
species are easily differentiated
If a board, rock or other object on which the nymphs are living be
rapidly lifted from the water and the underside examined,a mad scrambling
will be observed as the nymphs of Stenonema seek to return to the seclusion
of their underwater home. Very soon after the first movements of the nymphs
and the water begins to drain away from the support, all movement ceases
and detection of the immatures becomes rather difficult, but if a little
water is dashed over the object, the nymphs again begin to run about.
Very few of them aotually reach the rim of the support and drop off, al
though some do successfully escape in this manner.
Swimming actions are very awkward and it is immediately obvious that
Stenonema nymphs are certainly not adapted as freely ranging inseots.
Progression by swimming is in one direction only, forward, in contrast to
walking in which the nymphs can go in almost any direction with equal ease*
An undulating motion is the driving force in swimming the head is first
depressed and the wave travels along the abdomen to the caudal filaments
which lash out with but little effect for they are almost devoid of long
hairs such as make the Baetinae such efficient swimmers. The swimming act
never carries the insect very far and after a few strokes, the nymphs settle
on any objeot which comes within reach, whether it be animate or inanimate.


140
suggested that there are three distinct stocks in the family Ephemeridae
as it is known in North America# Hexagenia and Ephemera# which are closely
related, represent one. "Campsurus represents another stook. Pentagenia
and Polymltarcys [Ephoron] are close relatives and represent still another
stook, although they are more distinct from ea*h other than Ephemera
and Hexagenia are from one another.
"Potamanthus stands as an intermediate between the other Ephemeridae
and the Leptophlebildae..."
Hexagenia limnophila ms. name
TAXONOMY* For some time, a large series of mayflies in my collection
were considered to be Hexagenia orlando, but in November, 1938, Dr. Traver
kindly compared some of the Florida specimens with the type of orlando
and found that they were definitely not this speoies. Another worker
on mayflies suggested that the speoies might be kanuga, and Miss Traver
therefore compared the Florida specimens with the types of kanuga. She
wrote (letter, 1938) that the Florida specimens "are slightly larger
[than orlando], the oolor pattern of male distinctly more extensive both
above and below, on abdomen? the hind wing of yours is not dark-bordered,
as in orlando. That fact, plus the much greater development of the dark
ventral abdominal triangles, makes me hesitate very much to call your
specimens orlando. On the other hand, they are quite definitely, I think,
not kanuga? the ventral triangles of yours extend higher on each stern-
ite? the tarsi have more blaojc on them? the size of yours is too small?
tails not quite identical, although quite similar? no discontinuous
black border on hind wing as in kanuga. In short, I do not know whether


238
"The insects did not at any time rise more than twelve inches aberre
the. surface of the stream (flight took pla.ee over the middle of the creek)
and horizontal distance covered did not exceed three feet. The flight
tras fairly rapid. As I swept my net, many were able to escape the gentle
sweeps which were necessary, for the males are T8ry fragile all cap
tured by sweeping were Injured.
"The entire flight took place in bright sunlight except toward the
last. As the sun moved, trees began to cast shadows over the area in
which the remaining single male was dancing, but these shadows had little
effect on his position. The flight was usually downstream against the
wind but occasionally it become transverse and once or twie, the insect
was headed upstream. The male seemed to fly backwards, forwards, sidewise,
or obliquely with equal ea.se. When downstream, the flight was forward and
backward, but when crosswise, the flight was from side to side. During
the flight, the abdomen drooped considerably, being at an angle of about
sixty degrees or more with the horizontal and sometimes becoming almost
perpendicular* The tails could occasionally be seen if the light happened
to strike them at the correct angle.
"The flight resembled nothing so much as a mechanical toy attached
to an invisible string. Running the length of the string, the toy is
suddenly jerked backwards, then immediately runs out again." The movement
is diagramed in figure 3 *
ilever during the entire flight did the insect do an about face to
move upstream. Now and then, the mayfly appeared to touch the surface of
the water, but it would, immediately rise when this occurred.
Spider webs (of letragnatha sp.) are common along the creek where flights


314
proximately five to six mimttes after emergence from the nymphal skin
This is one of the shortest-lived of all mayflies. Laboratory
roared adults remain alive about four hours although a slight reflex
movement of the legs oan still be observed thirty minutes later*
I have never observed the mating of this species and there seem
to be no written aooounts of the mating flights of any other species of
Caenis; however, I did note a flight which may have been the mating
flight of C* diminuta* About 300 p* nu, January 25, many subimagos
were seen rising from the surface of Orange Labe* They flew to the
most available support where they soon molted and, as imagos, became
very active* At 346 p* m* a single male imago was noted rising and
falling in a typical mating flight behavior about three hundred yards
from shore (but still within the bonnet zone)* It flew about five feet
above the water with a vertical rise and drop of' about two feet but there
was little horizontal movement* The male was soon lost to sight*
The ooupling of a pair of £ diminuta imagos was seen a few days
later by Dr* H* H* Hobbs, also at Orange Lake* The pair flew about five
feet above the water with but little rise and fall* After about thirty
seconds the two individuals separated and soon disappeared*
DERIVATION OF THE SPECIES It seems, for the present, unprofitable to
disouss the phyiogeay of this species for the characters by which it is
distinguished from its allies are merely those of color and pattern, aside
from slight differences in measurement che forceps of the male.
These features are probably not indicative of true relationships*
C, diminuta is a lowlands speoies, wnioh,if it originated in the
northern part of North America, migrated into Florida by taking advantage


385
bably only one generation produced at these upper stations in a season#
HABITSi The living nymphs can usually be distinguished from those of
B# spinosus and australis without microscopic examination, although they
are superficially similar and agree in body size and in length of oaudal
filaments# When nymphs of B# intercalarle are placed in a white enamel
pan in a small amount of water, the gills are spread outwards from the ab
domen so that they overlap its borders considerably# Furthermore, the gills,
as seen against the white background, frequently have a greenish tinge.
Spinosus and australis, on the other hand, usually hold the gills much closer
to the body, and the gills are relatively colorless. In addition, the
caudal filaments of interoalarls are usually less intensely banded than are
the filaments of spinosus and australis# Swimming and clinging activities
of intercalara are very similar to those of spinosus.
The nymphs live in the swiftest water on vegetation, clinging near
the upper, free ends of the leaves where the full force of the ourrent
can strike them# Remaining on the under surface of the leaves, they feed
on the materials covering the plants chlofly algae, although diatoms and
desmida are frequently eaten as well as plant epidermis#
Although the upper surfaces of the rooks in the Santa Fe river are
completely covered with the moss Fontinalis, this is not a habitat of B#
intercalaris probably on acount of the slowness of the current and heavy
silting where the growths occur# Interoalaris is one of the most rheo-
colous of all the mayflies inhabiting Florida streams#
LIFE HISTORY The limits of toleration of B# intercalara are not very
great, and consequently rearing in the laboratory presents earn difficulties.
Many times I have attempted to bring live specimens to Gainesville from


67
much more than *5 on either side of a pH of 7.0*
(2) Silt-bottom lakes This type of lake is well exemplified by Lake
Newnan near Gainesville. The lake is quite large, being about ten miles
in length and about three miles wide. It is bordered by a ring of eypress
which extends from dry land into the water. Also margining the lake, water
hyacinths form dense growths between the bases of the cypress trees and
extend out into the lake as far as there is a protected zone. V/ith every
shift in the direction of the wind, water hyacinth plants break free and
float across the lake, pushed onward by the wind. Frequently, during a
period of sustained moderate winds, the lake is dotted with numerous floating
"rafts of water hyacinths; eventually these plants pile up along one
shore until the wind again changes and sends them sailing back to the opposite
3ide. The continual rain of dead water hyacinths onto the bottom of the
lake has given rise to a thick layer of loose fluffy silt which completely
covers the bottom to a depth of two or more feet* almost no living organ
isms can be found in these bottom deposits for conditions are not conducive
to life. The lake is shallow; in the middle it is not much more than ten
feet in depth, and over most of its area it is shallower than this. The
water has a definite brownish tinge and is rat her turbid*
Numerous other lakes in the central highlands also belong in this
same category. Orange lake, one of the larger lakB3 of this region, is
similar to Late Newnan in its type of bottom, bub is is deeper, has much
rooted vegetation in the form of water bonnets, and is somewhat exceptional
in having numerous floating islands of vegetation. Some of these floating
islands are large enough to support trees, but the great majority are small
clumps of vegetation which float about,changing location with each change


382
the relationship of interoalaris to them*
DISTRIBUTION! If the Florida fora is interoalaris, the distribution of the
species is certainly most interesting, for it is known only from Ontario
and from Florida* Suoh distribution, with no records of the species from
the intervening area between this northern and southern region, introduces
some doubt as to the validity of the identification of the Florida specimens
as interoalaris, but the very close correspondence of the insects to the
published descriptions oannot be denied* In June, 1940, a single male imago
was taken from a bridge near Wetumpka, Alabama, and it fits the description
of interoalaris fairly well, except that the wing length falls far short of
the measurements given for that species* If this male is interoalaris, it
would offer a slight connecting link between the northern and southern forms,
for this male was collected just at the edge of the Fall Line on the Coastal
Plain side*
Southern nymphs or adults of interoalaris are known from Hillsborough
oounty, Florida, to Elmore oounty, Alabama. In Florida, the species is
rather widespread, but not so widespread as is spinosus* The cheok on the
range is apparently ecological, since the nymphs seem to be less tolerant
than are those of spinosus* (See rr\a.p /f)
ECOLOGY* Basic streams where the flow is swiftest support the most prosperous
populations of B* interoalaris nymphs* Although the species does inhabit
aoid waters, the creeks are usually only slightly aoidio and have sand bottoms*
In the central portion of Florida, nymphs have been collected in greatest
numbers from the Santa Fe river and from the Hillsborough river, both basio
streams. The nymphs are very rare in the sand-bottom streams of peninsular
Florida, and,in Alachua county where collecting has been most intensive,


Portland (April 3, 1933, H* H, H* and L J, M,, adults)j 9,5 miles west
of Portland (May 31, 1940, H. K. H* and L* B, nymphs and adults)j 5*4
miles east of Freeport (April 2, 1938, II, II, E, and L* J, M, nymphs)j
13,8 miles west of Freeport (June 7, 1938, L, B,, nymphs and adults)j
11.4 miles east of Niceville (April 3, 1938, H. H, H. and L. J, M,, nymphs),
Washington Co. Holmes creek (April 2, 1938, H, E, E, and L, J. M*,
nymphs)*


208
gaera of ephemerids, nymphal Odonata, chironomid larvae, and the small
snail Physa* Mayflies, however, far outnumber their coinhabitants of
these detritus drifts* Besides the Blasturus nymphs, there have been
found Habrophlebiodes brunneipennis, Paraleptophlebla volitans, Steno-
nema smithae, Caenis diminuta, Ephemerella trilineata, Hexagenia weewa,
and Cloeon nyssa*
Maoroscopio inhabitants of the submerged moss bank are most commonly
mayfly nymphs and less frequently dsmsel-flies and bloodworms* Nymphs
of Paraleptophlebia volitans are found more often in this moss than are
the immature Blasturus intermedius* Some Stenonema smithae nymphs also
occur here*
SEASONS* In general, seasons have no great effect on mayflies in Florida,
but Blasturus seems to be an exception* This genus is the earliest of
those mayflies of Florida which are seasonal; its sexual aotivity gradu
ally increases to a maximum in February and March, and then gradually
declines*
There is much overlapping of mature forms with immatures* In Feb
ruary, 1940, I collected numerous nymphs of B* intermedius from a small
creek near Gainesville; here, mature nymphs outnumbered very young and
half-grown nymphs almost ten to one. This would seem to indicate that
in Florida this species, unlike the majority of mayflies, has a definite
maximum emergence period, with most of the individuals maturing in Feb
ruary to March but with some emergence throughput spring and early summer*
HABITS* The nymphs of Blasturus intermedius feed upon detritus, diatoms,
and algae, scraping the surface of the deoaying leaves unmindful of the
materials on the leaf be they animal, vegetable (preferable), or mineral;


232
areas* The temperature of the water rarely v ries more than fifteen
degrees centigrade.
Common associates of brunneipennis are other mayflies and Odonata*
The mayflies are Paraleptophlebia volitans, Blasturus intermedins, .Bteno-
nema smithae, Baetis spinosus, B spiethi, Acentrella ephippiatus, Pseudo-
cloeon alachua, and Hexagenla weewa. Odonata: Dromogomphus spinosus,
Libellula spp., Macromia sp, Boyeria vinosa, Isohnura spp., finalIgma spp*f
Baeterina sp*, Agrin maculatum, etc* In the leaf drift there are present
large numbers of chironomids, caddis fly larvae (Hydropsyche, Mo lama, a 'jo. ),
occasional stoneflies (particularly Taeniopteryx nivalis), larvae of the
cranefly Tipula abdaminalis, various other dipterous larvae, and, very com
monly, the snail Physa* These associates make up the principle macroscopic
inhabitants of the leaf drift and riffles of small Florida streams*
SEASONS: K* brunneipennis is not limited by seasons, nymphs of all ages
being present in Florida streams throughout the year* Adults have been
taken in seven months of the year,leaving gaps only for May, August, Septem
ber, October, and December* There seems to be no emergence peak, for
examination of the nymphal fauna indicates that throughout the year the
distribution of immatures of all ages is approximately the same*
MBITS: The feeding habits of this species are not definitely known, but
I believe that they do not differ radically from those of other mayflies.
The we11-developed molar area of the mandible indicates that grinding of
food materials must be habitual* When a nymph is placed in an aquarium
with only plant materials (and of oourse numerous protozoans and micro-
crustaoea), it flourishes and does not seem to lack sufficient food for
normal growth. Examination of the nymphal gut of this species indicates


430
REFERENCES
Banks, Nathan. 1900. New genera and speoies of Nearctic Neuropteroid
insects. Trans, Amer. Ent. Soe. 26: 245-251.
1903# A new speoies of Habrophlebia. Ent. News. 14: 235.
Bartram, W. 1791. .u-avais mrough North and South Carolina, Georgia,
East and Vest Florida. Philadelphia.
Berner, Lewis 1939. A contribution toward a knowledge of the mayflies of
Florida* Ms. Thesis presented at Univ. of Florida* Pp. 1-119,
6 pis.
1940a. Ovoviviparoua mayflies in Florida. Proc. Fla. Acad.
Sci. 4* 280 (abstract).
...... 1940b. Baotisoa rogersi. a new mayfly from northern Florida.
Caad* Ent. 62t 156-100. plate 10.
- 1940c. Baetine mayflies from Florida (Ephemeroptera).
Fla. Ent. 23 33-45, 49-62. Plates 1 and 2.
1941* Ovoviviparous mayflies in Florida. Fla. Ent. In press.
Byers, C. F. 1930. A contribution to the knowledge of Florida Odonata.
Univ. of Fla. Publi. Biol. Soi. Ser. Vol* 1, No. 1. Pp. 1-327.
18 text figs., plates 1-11.
Campion, H. 1923. On the use of the generic name Brachyoerous. Ann.
Mag. Nat. Hist. 9: 515.
Carpenter, F. M.1933. The Lower Permian insects of Kansas. Part 6. Proo.
Amer. Acad. Arts and Sci. 68 (11): 487-503.
i
Carr, A. F. 1940. A contribution to the herpetology of Florida. Univ.
of Fla. Publi. Biol. Sci. Ser. Vol. 3, No* 1. Pp. 1-118.
Clemens, W* A* 1913. New species and new life histories of Ephemeridae
or mayflies. Caad. Slit. 45 : 246-262, 329-341, plates 5-7.
- 1915a. Bearing experiments and ecology of Georgian Bay
Ephemeridae. Contri, to Caad. Biology. Sessional Paper No. 39b.
Sit Pp. 113-128, 132-143.
ViT
1915b. Mayflies of the Siphlonurus group. Caad. Ent. 47:
245-260. Plates 9-11.
....... 1917. An ecological study of the mayfly Chirotenetes.
Univ. of Toronto Studies, Biol. Ser. No. 17. Pp. 1-43, 5 plates.


Caers nymphs can withstand the alternating conditions in the creeks pro
duced by the continual changes in level of the bodies of water connected
by the intermittent streams* Vegetation is usually abundant, but it is
not of the type found in constantly flowing waters* Also, the drying of
parts of the canal bed produces conditions which the stream inhabiting
mayfly nymphs cannot for long endure, and even if, by chance, a species
should become established during the period of flew, the cessation of this
flow would bring about the death of the immatures*
Permanent Creeks
Permanently flowing streams are the most important of the mayfly
habitats in Florida* The oreeks of this area may be divided arbitrarily
into the following categoriess
(1) Sand-bottom creeks with little vegetation*
(2) Sand-bottom oreeks choked with vegetation
(3) Silt-bottom creeks wrch little vegetation*
(4) Silt-bottom creeks choired with vegetation*
(1) Sand-bottom oreeks with little vegetation: These are small, shallow,
gently flowing streams with sandy beds* The oreeks vary from as little as
one foot to forty feet in width, and in depth from a couple of inches to
as much as five feet. The bottom is composed of loose, rolling sand which
builds up, in mid-stream, into small ridges behind which small masses of
debris accumulate* Large rocks almost never occur in Florida streams, but
pebbles may be found imbedded in gravelly riffles where the water becomes
quite siiallow. There are occasional pools, but they are not a conspicuous
element of the streams* The pools are usually small, quiet areas near the


321
LIFE HISTORY: In spite of the large amount of taxonomic literature con
cerning C* hilaris, its life history remains almost completely unknown*
DERIVATION OF THE SEE CIES It can easily be seen from the distribution
of C* hilaris along the eastern border of the United States, that it has
followed the moderately flowing streams of the Coastal Plain gradually
moving into those of northwestern Florida* One may wonder why the species
has not spread southward into the north-central region around Gainesville
where the streams are, in general, not dissimilar to these of the region
where hilaris does occur* It may be that C* hi laris is a recent entrant
into Florida and the time has been too short for migration to proceed this
far southward, but the apparent ease of dispersal of Caenls makes this
seem unlikely*
LOCALITY RECORDS Bay Co* 14*1 miles north of Panama City (June 8,
1938, L* 3., nymphs); 24*7 miles north of Panama City (June 6, 1938,
L* 3*, nymphs); 28*7 miles north of Panama City (June 8, 1938, L B,
nymphs). Gadsden Co River Junotion (July 1, 1939, L* B*, nymphs)*
Jackson Co* 3*6 miles north of Altha (December 1, 1939, L* B*, nymphs);
Blue Springs Creek near Marianna (July 1, 1939, L* J* M* & L* B*, adults;
June 6, 1940, ii* H* H* & L* 8*, adults), Leon Co* 7 miles south of
Hwy, $19 on $127 (June 5, 1938, L B*, nymphs)* Liberty Co, Sweet
water Creek (June 10, 1938, L* B*, nymphs; November 4, 1933, L* B*,
nymphs; July 1, 1939, L. E#, nymphs; December 1, 1939, L* B*, nymphs);
eastern county line at Hwy* #19 (November 30, 1939, L. 8, nymphs). Okaloosa
Co, 6,1 miles west of Walton County line (May 31, 1940, L* B,, nymphs)*
Wakulla Co, Smith Greek (June 5, 1938, L* B*, nymphs)* Washington Co*
Holmes Creek (July 2, 1939, L* B*, nymphs).


173
stock, and cannot rightfully be linked with any of the other extant fam
ilies.
"Oreianthus sp. Ho. 1 Traver
TAXONOMY* The nymphs of "Oreianthus sp. No* 1" were well described by
Traver in her paper (1937* 83-84) "Notes on the Mayflies of the South
eastern States." Her specimens were taken in the identical locality from,
which I have subsequently collected nymphs corresponding very closely
with the original description* Traver suggested that the differences
between "Oreianthus sp* No. 1" and 0. purpureus might be generic rather
than specific* The validity of this suggestion must be tested through a
study of the adults and the adult of "species No* 1" is still unknown*
At first glance, one is apt to oonfuae the nymphs with those of
Caenis,but closer examination immediately distinguishes the two, for
Oreianthus has prominent metathoracic wing pads* In the later instare
Oreianthus nymphs are much larger than are those of Caenis*
DISTRIBUTION* "Oreianthus sp* No. 1" has been recorded from the Piedmont
in Georgia, Columbus, Georgia (on the Fall Line), and from Liberty county
in the Coastal Plain of Florida. The species has subsequently been collect
ed in various streams draining into the Apalachicola river, and from
Okaloosa county in the Yellow river drainage. The Florida distribution
of Oreianthus is very limited,but the reason for this limitation is not
at all olear for the species is quite tolerant, (jet i)-
ECOLOGY* Although many streams in northern Florida have been examined
and oolleotions made in all types of situations in them, "Oreianthus sp.
No. 1" was seldom discovered. It was found in the streams draining the


210
and at the same time to twist into their normal position Immediately af
ter emerging, the subimago is a dull gray with rather translucent wings
but after a short time the animal begins to darken until it is quite black
ish The time consumed between exposure of the split mesothorax and re
moval of the wings varies from one to three minutes Once the wings are
freed, the animal rests supported partially by the surface film and parti
ally by the floating nymphal skin During this resting period the wings
are frequently vibrated Having regained its strength, the subimago begins
to walk away from its exuviae and slowly pulls its three caudal filaments
from their sheathsj these, when freed, are slightly raised above the
surface of the water* After resting again for a short time, the winged
insect flies or crawls to some nearby support to await the bodily changes
which will force it either to undergo a final molt or perish.
To undergo its imaginal molt, the subimago establishes itself firmly
on its support and begins to strain at the mesothorax. This straining is
probably localized in this part of the body because of the tremendous
wing muscles located in the synthroax* The contraction of these muscles
forces the wings to spread outwards until they touch the support* As the
adult pull himself from his subimagal skin, the wings are gradually drawn
in towards the body until they lie along side the abdomen and are folded
fan-v-rise. The withdrawl is slow and when the wings are almost freed, the
creature releases its adult legs from the attached skin and fastening its
claws to some object pulls the wings free Immediately, the wings are
raised, but only to about a sixty degree angle with the horizontal. The
adult rests a moment, flexes its wings, approximates them in the usual
manner and then slowly walks away pulling its tails out as it moves. The


33
the media tail of these genera has heavy growths laterally; in many
others, the three tails are almost bare, having only a light covering of
short hairs*
Color pattern, while frequently used for species determination, is in
no wise as frequently employed as in the adults* Often when suoh charac
ters are found to distinguish species, sturctural differences parallel
them*
A COMPARISON OF- FLORIDA MAYFLIES WITH THE NORTHERN FAUNA
Taxonomy
The genera of mayflies ooourring in Florida, except Oreianthus, are
found over the entire eastern part of North Amerioa, and even Oreianthus
is known as far north as North Carolina* It is of interest to note that
many of the genera suoh as Ephemera, Choroterpes, Habrophlebia, Kabrophle-
biodes, Pseudooloeon, and Trioorythodes have never before been reoorded
fresa the Coastal Plain, but all of these are now known to occur in Florida*
Trioorythodes was previously taken no closer to Florida than Texas and West
Virginia, while Choroterpes me recorded only as close as Texas and northern
Ohio*
Thirteen of the Florida speoies are found also in southern Canada,
Chio, and New York as well as other areas in the north* In addition, there
are several other speoies which are very similar to those described from
the northern region but which differ in minor oolorational or genitalial
characters# It is to be noted that all but one (Bexagenia bilineata) of
these wideranging species are small forms* This conforms with the general!


378
growths of Isnardia, Perseoaria, and eel grass, but,even though this vege
tation was so plentiful, the mayfly fauna was not excessively large
Associated with B australis in Alachua county streams are Pseudo-
cloeon alachua, 3aetis spinosus, B spiethl, Stenonema smithae, and Para-
leptophlebla volitans In the west Florida streams, B. spinosus, B spiethi,
Acent relia ephlpplatus, Paraleptophlebla volitans, Stenonema smithae, S.
proximum, S* exiguum, Ephemerella trilineata, E* ohoctawhatchee, E. apala-
chicola, Choroterpes hubbelli, Trioorythodes albilineatus, Caenls hilaris,
Pseudocloeon bimaculatus, and Centroptilm viridocularis have been found
along with B# australis*
SEASONS: Adults have been reared or collected only during March, May,
September, and October; emergence, however, is not seasonal in Florida
Nymphs which appear to be australis were collected in June, and ranged in
size from very immature to full grown* Very likely the young specimens
would have emerged some time during the winter.
HABITSi There seem to be no essential differences between the habits of
B australis and B spinosus nymphs*
LIFE HISTGEf: The immature stages probably last from six to nine months,
but there is no substantiating evidence* The mode of emergence does not
differ from that of B. spinosus* The subimago emerges during the afternoon
about two or two and one-half hours before sunset; in early September, this
was from 4:30 to 5:00 p* m* All subimagos which were observed in the field
emerged from very small streams, and in every case the insect flew to the
nearest support and settled about three or four feet above the surface cf
the water* After seven to ten hours, the subimaginal molt takas place and
the imago remains quiescent until time for the mating flight* I have not


189
Campsurus incertus Traver
TAXONOMY* For two years, I searched for nymphs or adults of Campsurus
in Florida, because the distribution of the North Anerioan speoies clearly
indicated that some member of the genus should certainly ooour in Florida*
Naturally, since incertus was known from the drainage of the Apalachicola
river in Georgia and Alabama, it was logical to expect that it would al
so be found in the same drainage system in Florida,and this proved to be
the case* The only Florida specimens secured were taken by Mrs* Long,
the proprietress of a store and filling station near the Apalachicola
river at Bristol* She had previously informed me that the "willow-flies",
during the summer,formed huge piles under the lights outside the store*
I asked if she would be kind enough to drop a few of these "willow-flies"
into the bottles which I left with her, and departed, expecting to hear
no more about the matter* Much to my surprise, two months later the bottles
arrived filled with females of £* Insert us, the same insect which all my
search in this region had failed to reveal* No other Florida specimens
have been seen*
When Traver described C* incertus she stated that it might be
synonymous with puella, described by Pictet in 1843 from New Orleans,
and not since taken* This question is still unsettled* I have no males
of incertus and cannot say without question that the Florida specimens
are this species however, the color pattern is very close to that des
cribed by Traver and the distributional evidence supports this determina
tion*
DISTRIBUTION* C* incertus is known from Spring Creek and Albany, Georgia,
Eufaula, Alabama, and Bristol, Florida, all in the drainage of the


197
nymphs of tiie two species, at least none have been found in the speci
mens at hand# although it is reasonably certain that both species are
represented in the immature stages. Because a single adult male was collec
ted at the Suwannee river and several adult and subimago specimens were
taken in Liberty and Gadsden counties, the nymphs from these localities
are here included under I* pictipes. Those nymphs taken west of the Apala
chicola river are being placed tentatively as perdido,although both speoies
are probably represented in the collection from this region.
Published references to pictipes since its description include only
its redescription by Traver in her taxonomic treatment of North American
mayflies.
DISTRIBUIION: The species is found in the Coastal Plain and Piedmont.
The published locality records have been given, above. In Florida, the
species has been found to range from Alachua county to the Apalaohicola
river. I. pictipes probably is dispersed throughout western Florida into
Alabama and thence into the Piedmont of Georgia, from which area the
allotype and paratypes were taken, (fee
ECOLuGY: The ecological relationships of the nymphs are identical with
those of L. perdido.
SEASONS Adults in my collection were taken in May, June, July, and dried
adults were found in December stuck in tar covering the underside of the
bridge over Sweetwater creek. Travers specimens from Georgia were taken
in late Lay and in August. Nymphs from the Suwannee river in all stages
of development were collected in April; the Santa Fe river specimen was
mature by Maroh 18. It appears from the above data that emergence occurs
throughout the year.


248
acid or circum-neutral. Red-water Lake, ore of the two lakes from which
specimens have been taken, cerives its name from the color of its water
which is definitely aoidio As can be seen by the distribution of the
mayfly, the nymphs shun the non-flowing waters of the eastern and southern
part of Florida#
In sand-bottom streams, C huboelli may be associated with numerous
other mayfly species Acentrella ephippiatus, Baetis spiethi, B* spino-
sus, B australis, Centroptilum viridooularis, Habrophlebiodes brunnei-
pennis, Faraleptophlebla volitans, Tricorythodes albilineatus, Bphemerella
trilineata, Stenonema proximum, Stenonema smithae, and jS. exiguum. In the
silt-bottom creeks, its associates are B la stums intermedlus, Kabrophlebio- \
des brunneipennis, Stenonema smithae, Cloeon rubropiotum, Baetis spinesus,
and tlexagenia weewa. The lake associates have been mentioned previously}
C. hubbelll is the only mayfly inhabiting Jerome Sink
SEASONS a Adults were taken or reared during the early part of March, in
April, May, June, July, August, and October. There are no records for
nymphs or adults during any other month} however, I believe that emergence
occurs throughout the year, but that it readies its peak during the spring
and early summer. Emergence records for other species show that the north
ern forms emerge from July to the early part of September. C. nanita from
Texas was described from specimens taken in June; the types of C Okla
homa were collected Maroh 20j Eaton, in describing C. inornata from Mexi
co and Arizona and C. nervosa from Guatemala, failed to give date of
collection, but it would seem likely that these species follow the same
departure from the northern species as does hubbelll.
HABITS: Just as in other species of the subfamily, C* hubbelll is definitely




43
flies are wind and water* Of these, the latter, as far as the actual
establishment of species is concerned, is by far the more important, for
the immature stages of all Ephemeraptera (except a very few brackish water
species) require fresh water*
The ability to fly allows for the greatest amount of movement of
ephemerid species, although the adults are more or less oonfined to moist
situations* The relatively short life span of the imagos must necessarily
limit the flight range of the insects; however, the area ocoupied by a
species can be extended somewhat through voluntary flight of the adults*
Such small, feeble inseots as mayfly imagos are easily carried by the
wind* This can be seen in the present distribution of the moire diminutive
genera, Caenis, Baetis, and others, whioh are found throughout the world*
Dr* P* A* Glick, of the D* S* Bureau of Entomology, has made a thorough
and very interesting study of the distribution of insects, spiders, and
mites in the air* By means of traps suspended from the wings of an airplane,
he collected many thousands of insects from various strata of the air* His
results as far as the Ephemeroptera are concerned are listed below:
Caenis
Caenis sp*
Hexagenia
Ephemera
Undetermined
sp*
hiiaris
sp.
sp*
Over 5000
ft*, day
5000 ft.,day
night
4000 ft*,day
night
3000 ft*,day
night
1
2000 ft*,day
1
1
- ... ^Sht
1000 ft*,day
1
night
2
500 ft*, day
night
2


S3
light from any vegetation which might attempt growth on the pond bottom,
when there is any wind the duok weed piles up and leaves clear areas
on the water surface, but as soon as the wind dies down, the plants
again spread evenly over the surface. Amphipods (liyallela azteca)
are exceedingly numerous in these pends living among the duckweed, but
bottom organisms are scarce probably because of the small amount of
oxygen. The bottom of this type of pond has rather thick accuaulat ions
of black silt, heavily loaded v.-tth hydrogen sulphide, covering the
sandy bottom, and almost anaerobic conditions exist there* The sink
hole ponds are usually about one hundred to three hundred feet in
diameter, and are mostly round in shape. Some of the larger ponds
are formed by the coalition of two or more sink-holes.
(2) Fluctuating pondsi These constitute one of the more frequently encount
ered types of Florida ponds. Water fills shallow basins some mere
depressions in the original sea-laid sands, the majority produced by solu
tion of underlying limestone or by wind action. The level of the water in
these hollows varies with the amount of rain and surface runoff. There is
a great fluctuation in the area occupied by the water beoause a slight
rise or fall causes marked spread or retreat of the margins, but the depth
usually does not change greatly because of the shallowness of the pond. True
aquatic vegetation follows the rise and fall of the water to some extent,
but it is chiefly confined to the region below the more permanent water level.
"These periodic and sporadic fluctuations [due to the rainfall] prevent the
development of any permanent vegetation within the broad zone of fluctuation*
As the water recedes in the dry season, it leaves a belt of saturated earth
in which some grasses and sedges spring up among mats of stranded algae and


351
vanoed type than those speoies whioh are included in Baetis proper* From
the standpoint of the nymph (of ephippiatus), there are no differentiating
characters which might warrant a generio separation from Baetis, and in
them phylogenetio indicators point to no advances over Baetis* The two-
tailed nymphs might indioate that this group of speoies in which they oocur
is intermediate between Pseudocloeon and Baetis, even though EU. blcaudatus
has but two oaudal filaments* Spieth concluded that "it is possible that
even Pseudooloeon should be considered part of the genus Baetis, comparable
with the short winged forms known among Drosophila, leaf hoppers, beetles,
parasitic hymenoptera, gall wasps, etc.
Aoentrella ephippiatus (Traver)
TASONOMTi Traver described A* ephippiatus in "The Biology of Mayflies"
(1935) as Baetis ephippiatus, but based her description on males only*
In 1937, she reereoted Aoentrella, and by this action removed ephippiatus
to Bengtssons genus. The nymph of this speoies was described by me in
1940, and at the time it was pointed out that this speoies, on the basis
of the nymph, formed an intermediate between Baetis and Aoentrella*
The adult male is easily distinguished from the various Baetis speoies
by the absence of the costal process from the metathoracio wings; the
adult female is less easily separated* I have found that the best character
for separating these females from those of B* spinosus and B* spiethl is
by the presence of a distal femoral band on each leg of ephippiatus* The
nymphs are distinot from all other Florida speoies in having a strongly
colored seventh pair of gills; without use of this character, many of the
nymphs might be confused with Baetis spinosus, for the maxillary palpi


218
light OE the subject of the geographical distribution of mayflies* A
spring stream, especially near its source, supplies a remarkably uniform
environment for mayfly nymphs, wherever the stream occurs in warm climes,
at high elevations on mountains, or in the north* This uniform environ
ment provides a pathway by which organisms may extend their range wherever
this environment Is present* As one goes north, however, the warm-season
forms will be eliminated and the forms of the source, or near it, vd.ll
still be accomodated further downstream, and, provided the source becomes
colder, there is an opportunity for new forms to appear at the source*
The forms near the source are those with a northern distribution in gen
eral, and those lower down have a more southerly distribution*
"It is probably safe to say that a spring stream in its fauna, taken
from the warmer reaches to the source, recapitulates south to north dis
tribution, in the way that a mountain in the torrid zone gives in its fauna
and flora, taken from the foot to the top, roughly a vertical section of
geographical distribution frcm torrid to frigid zone*"
In Florida the nymphs of P# volitans live in the quiet areas in slowly
to moderately swiftly flowing streams amid the leaf debris. Though most
commonly found in these situations, they may also be taken from riffles,
submerged sticks and logs, submergent vegetation, etc*, but they seldom
venture into the swifter waters* The creeks supporting populations of
volitans are not more than three to four feet at the deepest point, and the
nymphs tend to remain in the shallower areas* The small streams draining
the ravines of the Tallahassee Kills region, although heavily populated
with Habrophlebiodes brunneipennis, are completely lacking in P* volitans*
Just west of this region, the latter species is found in the larger streams


371
at the surface of the water and almost immediately the subimago pops free,
the whole process taking not more than five to ten seconds. Naturally, in
such rheoeolous forms, rapid emergence would be an absolute necessity un
less they migrated into slow waterj even those Baetis nymphs which happen
to be in almost stagnant water will emerge very rapidly.
Numerous attempts to rear the species in quiet water in the laboratory
failed* Individuals were, however, successfully reared in a cage plaoed
in such a way as to allow a 6low but steady stream of tap water to flow
through it. The use of an aquarium with an aerator which gave off a steady
stream of bubbles, stirring the water and disturbing the surface, gave an
even greater degree of success. Apparently this stirring of the water in
some way aids the subimago in releasing itself from the nymphal skin, per
haps by battering, perhaps because the increased amount of dissolved gases
In the water aids the nymph in obtaining the air necessary for floatation
and loosening of the skin*
With respeot to the longevity of the adult, the male shows almost
no signs of life at about thirty-eight to forty hours after emergence.
The female adult, subimaginal and imaginal stages inclusive, may live as
long as forty-eight to fifty hours. Mating obviously must occur very soon
after the subimaginal molt, and oviposition shortly after that.
DEHIVATIN OF THE SPECIESt Baetis spinosus probably entered the state when
the streams were fairly young,and has followed the flowing water into all
parts where ecological conditions are propitious. One route of entry was
probably by way of the Spalaohicola drainage, and the present distribution
tends to bear this out rather strongly for adults have been recorded fresa
the headwaters of this river. The species may have entered Florida by other


Fig* 1* Normal annual temperature and precipitation, as compiled
from all available records to 1917 inclusive* Lines with numbers
and the degree mark () at the end indioate temperature; shaded
portions indicate inches of preoipitation during the year*
(From "The Climate of Florida" by Mitchell and Ensign)


93
22
23 (21*)
23*
24 (13*)
24*
25 (24)
25*
26 (25*)
26*
wIsoayehla ap G"
No such coloration on th outer margin of the gill platas*
"Isonychla sp B"
Found in th westernmost part of Florida*
Isonychia perdido
Found in the Apalachicola river region and eastwards.
Isonychia plotlpes
Gills present on abdominal segments 2-6, 3-7, or 4-7. If pre
sent on segments 2-6, those on segment 2 are lytroid, covering
all others behind them, and are triangular in shape* Hind
wing pads present or absent (see fig* 20)
Ephemerellinae (25)
Gills present on abdominal segments 1-6 only, rudimentary on

segment li gills on segment 2 elytrold, covering all others
behind them, and are rectangular in shape* Hind wing pads
absent.
Caenina (29)
Gills present on segments 2-63 elytroid gills triangular* Hind
wing pads absent.
Trioorythodes albilineatus
Gills present on segments 3-7 or 4-7* Hind wing pads present,
(see fig* 20).
.Spheme relia
Gills present on abdominal segments 3-7.
(26)
(27)
Gills present on abdominal segments 4-7 (see fig 20).


19
concomitant changes in shape of the me sot horade wings but no relative in
crease in resulting wing surface# In Gaonis, which lias entirely lest the
hind wings and in which the body is thick and heavy by comparison with that
of the Baetinae, the fore wings have become enlarged and broadened consider
ably at the anal angle# Although certain other genera of mayflies have
lost their metathoracio wings (Pseudooloeon and Cloeon), there has been no
such relative increase in sise of the fore wings, but the body is lightened
to accomodate the lessened wing surface#
There are few specializations in the genitalia of mayfliesj however,
in the more advanced genera there appears to be a fusion of segments of
the forceps, and in Caenis and Braohycercus this has reached its culmination,
the claspers consisting of but a single segment# The males of the more
specialized species also show a fusion of the paired penes, although the
vasa defferentia still open to the outside separately, and in the Lae time
the penes have become internal#
Although the Leptophleblinae are not the most highly specialized may
flies, certain of the females have the sternites of the seventh, and eighth
segments modified to form a simple ovipositor. The ovipositor is really
nothing more than a prolongation of the egg valve of other mayflies, arid its
value in oviposition is entirely unknown*
All mayflies supposedly have ten abdominal segmentsj however, in Baetisca
and the European Prosopistoma there seoms to be some amalgamation of the
segments, although it is claimed that ten segments can be distinguished*
The first abdominal segment of Baetisca is intimately related to the meta
thorax, and it is only with difficulty that this segment can be differentiated#
Spieth (193T) considers that in the nymphs of Baetisca gills are found on


154
peating* (Trovar, 1951i 607) "The capture of Hexagenia weewa occurred
on this wise* Prof. C. R* Crosby and I were passengers on the Apalachi
cola River steamboat John C. Callahan, Jr* On the evening of the eighth
of April, this big boat ventured up the Chipla River above Dead Lake to
Cotton Bluff to take on some barrels of turpentine* Near Cotton Bluff
the boat got stuck in one of the bends of that orooked little stream
just at nightfall* The searohlight was turned on, and in the beam of light
that it cast upstream the mayflies rose above the black waters by thousands*
Along.with multitudes of midges and a few other mayflies of the genus
Ephemerella, the big yellow female Eexagenias came fluttering up to the
light* They settled all over the front of the boat, two or three layers
deep wherever there ms support* They flew in our faces and clung to
our clothing# One could gather them up by barrelsful* But among the many
thousands of females, only two or three males were seen."
The nymphs are extremely hardy* I brought twelve of them a distance
of three hundred miles in tv/o small vials filled with moist silt, and these
individuals were not removed from the bottles over a period of more than
twenty-four hours* Upon my return to Gainesville, every nymph was found
to be alive and apparently in good health. Further, I left Gainesville
for two week6 and during this tine, the water evaporated from the pans
containing the nymphs until the surface of the mud was completely dry*
When water was added to the mud and it was stirred, out swam the nymphs
none the worse for this dessication*
Associated with H* weewa in the silt of the stream bed are some of
the burrowing dragonfly larvae, but the only other mayflies are Caenis
hilarls and C* diminuta which do not burrow but frequently live on top of


/£ /finj wi'oj c/-
/Cfsi OSH.S




180
be placed in the Baetidae* It would seem to be a connecting link between
the Heptageniidae on .the one hand and the Siphlonurinae on the other.
Since this last treatment of Siphloplecton and the higher categories
there have been no further disoussions of its relationships,and there
seems to be a tendency on the part of the current workers to accept Traver's
classification, at least in a modified form.
Siphlopleoton is a small genus, including only five known species, the
fifth recently described by Spieth as S. costlense.
The genus is distributed throughout the eastern part of Uorth America
from Manitoba to Florida* Spieth (1938i 3) discussed briefly the distri
bution of his new species in relation to the distribution of closely related
species* He finds that S. costlense is geographically separated from its
nearest relative by more remotely related species, a unique sort of dis
tribution among mayflies.
Phylogenetically, Siphloplecton is little known, but it is certainly
a primitive genus when considered from the standpoints of venation and
genitalia. As mentioned above, Dr* Traver suggested that it might be a
connecting link between the Heptageniidae and the Siphlonurinae*
Siphlopleoton speciosun Traver
TAXONOMfi The very distinctive nymph of S* speolosum was described by
Traver in 1932,along with the adult,from streams near Macon, Georgia, and
others near by* The species has not since been mentioned exoept for its
redesoription in the Biology of Mayflies" and a statement of its distri
bution by Spieth (1938i3) in his discussion of the distribution of S*
costalense. Beoause nymphs only are at hand, the specific determination


434
very similar to that of P. alaohua.
DERIVATION OF THE SPECIES: P. punctiventris probably entered Florida along
the same path followed by 3?. parvulum, i. e. the Suwannee river drainage
system. The occurrence of the species in the Macon region would seem to
lend weight to the idea, for this area is in direct line with the move
ment of the species from the north into the Suwannee. There is no apparent
reason why the species has not yet spread west of the Apalachicola river
(P. bimaculatus which occurs to the west of the river may be only a variant
of P. punctiventris).
LOCALITY EEC OSDS: Alachua Co. Santa Fe river at Poe Springs (March 12,
1938, L. B., nymplis; February 11, 1939, L. B., nymphs; February 18, 1939,
L. E., nymphs and adults; March 25, 1939, L. B., nymphs; March 1, 1940,
L. 13., nymphs). Gilchrist Co. Suvmnnee river at Oldtown (April 5, 1938,
L. B., nymphs; March 4, 1939, L. 3., nymphs). Liberty Co. Little Sweet
water creek (December 10, 1937, L. B., nymphs).
Pseudooloeon bimaculatus ms. name
TAXONOMY: This species is known from numerous nymphs, three females, and
one male imago (tentatively associated with the nymphs). The male adult is
distinct from other species of Pseudooloeon in its oolor pattern, chiefly
paired red spots on the abdominal tergites* these spots are also present
on the abdomen of the female. Nymphs may be separated from others of the
genus by the faot that the seventh pair of gills is deeply colored with
reddish brown; in addition, the abdominal maoulaticn is unique,and the band
ing of the caudal filaments and the length of the median filament in relation
to the width of the laterals are distinctive. The nymphs are very clearly


320
other months*
HAojITSs The nymphs are extremely minute, some last stage specimens being
even less than two millimetersj they are, consequently, very difficult
to see* I have found that the most efficient method of taking nymphs is
to put the debris,collected by means of a fine-screened, coffee strainer,
into a white enameled pan* As the pan is tilted and the water drains a-
way from the nymphs, a slight movement may be seen as the insects attempt
to follow in the wake of the liquid* Just as in C* diminuta nymphs, the
movement is a slow orawl combined with a somewhat wriggling motion* This
species does not tend to flick its tails over its back and young Tricory-
thodes and young damsel-zly nymphs may easily be confused with C* hllarls
unless separated with a hand lens*
The adults are strongly phototroplo and are attracted to lights along
with C* diminuta wherever the two oocur together* At Bit Springs Creek
a large electric plant faces the lake formed by damming of the stream,
and its lights are kept burning all night* The walls and windows of the
illuminated poroh are covered with spider webs, the spiders lurking in
every crevice to catch the rryriad of insects whioh are attracted to the
lights. I have examined the webs on several occasions and been well re
warded for my efforts! the predominant insects present were midges, but
Caenis adults were second in abundance, other insects occurring in much
smaller numbers* When one first examines these walls, he is amazed
by the mass of entangled insects and the ease with which spiders catch
them* It would seem to be truly a spiders paradise; the owners of
the building do not molest them because of their ability to do away with
insect pests*


113
later hatching to another My first attempt at rearing this species was
fairly successful, although the females which I secured were nearly spent
and contained on.y a few eggs in the anterior portion of the body; however,
these were fertilized and a number of nymphs hatched within approximately
fourteen days. A group of females were collected later which had only
begun oviposition and were completely filled with eggs; hundreds of nymphs
hatched from this latter batch
These last eggs were deposited on Ootober 5 They were examined on
October 15 and it was found that nearly every one contained almost fully
developed nymphs coiled within The first hatching was noted exactly two
hundred seventy hours and thirteen minutes after oviposition, and from this
time, hatching continued for four more days, with a predominance at about
twelve to thirteen days after laying
The movement of the nymph within the chorion as it tries to escape is
very clear. There is a forward,backward, and sideward motion of the head
as though the insect were scrapping it against the egg shell* however,
there is very little motion occurring in the more posterior portions of the
body which are tightly coiled. I observed this movement within individual
eggs lasting as much as two cays, with the final liberation of the immature
after this period
Finally, the egg ruptures along its longitudinal axis and the nymph
emerges, but the exit is rather slow and arduous The first part of the
body to pass from the shell is, of course, the head. As it is pulled, or
rather pushed, the chitin of the insect give in the median region much as
does cellophane when it is stretched As the head is pushed out, the
thorax gradually squeezes through, giving here and there to accomodate the


160
th beginning of rearing, there were forty-five nymphs confined in a
rather small panj at the end of one month the mortality ms found to be
very low, only five specimens having died. This low mortality rate con
tinued, with scattered emergences, until summer, when nearly all of the
remaining nymphs reached the last instar. For some unknown reason, these
were unable to transform* All of the nymphs seemed undersized and the
two imagos that were reared were certainly dwarfed, probably because of
limited quarters and insufficient food.
Associates of H, orlando are necessarily less nimerous than those of
H. weewa, since not so many mayfly species oocur in the region where the
former species is present. In Hogtown creek, Caenis diminuta was very
frequently encountered among the dead leaves covering the silt in whioh
Hexagenia nymphs burrowed. In the Santa Fe river, that part inhabited by
the burrowers has relatively few mayflies, predominantly Baetis spinosus,
Stenonema smithae, and Tricorythodes albilineatus,
SEASONS Adults have been either collected or reared in March, April,
May, and June, Traver collected adults in Alabama on July 2, Among the
nymphs that I attempted to rear, two reached their last Instar in August,
but did not transform to subimagos. The data from the Hogtown oreek speci
mens point to an early summer emergence as the predominating period for the
species. On May 1, many of the nymphs were in the tertiultimate, pen
ultimate, or last instar, and by the first part of July most of them had
died,
HABITS The habits of H, orlando are the same as those of H# limnophila,
except for ohoioe of habitat,
LIFE HISTORY Nymphal development probably takes one year. There is


284
line (May 31, 1940, H* II* H* and L. B, nymphs); 3.6 miles north of
Niceville (April 3, 1938, H* E. H. and L# J. M, nymphs).
Ephemerella hirsuta ms. name
TAXONOMY: Such an artificial barrier as a state line does not warrant
the amission of & discussion of this new species. I have only two nymphs
of E. hirsuta, taken by Dr. Hobbs and Mr. Marohend in April, 1938, from
Perdido creek less than one mile north of the Florida state line in Ala
bama. The specimens are very distinot and cannot be confused with any
Florida species. They definitely fall into the simplex group of Travers.
According to her diagnosis of this group (1932: 146), the nymphs are allied
to attenuate, but would be easily separated from the latter, for she says
the occipital tuberoles of this species are short and inconspicuous. How
ever, MoDunnough (1931b 209) described the nymphs of attenuata as having
"a pair of strong tuberoles on the oociput." Vifhioh are w to believe?
Nevertheless, E. hirsuta oan still be distinguished from attenuta by the
banding of the legs which differs from that described by MoDunnough.
DISTRIBUTION: As mentioned above, E* hirsuta is known only from Perdido
creek, just north of the Florida-Alabama state line. This creek flows
southwards to become the Perdido river. The distribution of E* hirsuta
is of particular interest when compared with that of the previously known
species of tts group* E. attenuata, the olosest relative, is known from
Ottawa, Ontario, southern Quebec, and the Potomac River; simplex is re
corded from southern Quebeo, Ontario, New Brunswiok, western New York, and
the mountains of North Carolina; margarita has been taken in Utah, Wyoming,
Montana, Alberta, and New Hampshire; "Ephemerella sp. No. 1" (Traver, 1937)


422
the summer generation, which is extremely minute*
HABITS The habits of this speoies do not differ from those of P* alachua*
LIFE HISTORY Only one male and one female have been reared* These
emerged during the afternoon about 300 p. m* and remained in the sub-
imaginal stage for about nine or ten hours* No other data are available*
DERIVATION OF THE SPECIES* _P* parvulun probably entered Florida through
the drainage of the Suwannee river, all its Florida distributional records
apparently indicating this. Furthermore, the distribution of P, alachua,
which may have arisen from parvulum, appears to bear this out* Migration
has probably taken place along the Appalachians into the Piedmont of
central Georgia and thence into Florida*
LOCALITY RECORDS Alaohua co, Santa Fe river (March 24, 1937, L* B.,
nymphs; March 12, 1938, L* B., nymphs; February 11, 1939, L. B*, nymphs;
February 18, 1939, L* B*, nymphs; March 4, 1939, L* 3, adults; March
25, 1939, L. B*, nymphs; October 25, 1939, L* B*, adults; imago reared
October 29)* Gilchrist Co, Suwannee river at Oldtown (April 5, 1938,
L* B., nymphs)* Liberty Co. Sweetwater creek (June 10, 1938, L, B.,
nymphs; July 1, 1939, L. N., nymphs), Taylor Co. Fenholloway river
(March 18, 1939, J, S. R,, H, H, H,, F. N. Y,, L. B, nymphs).
Pseudocloeon punotivenbris (MoDunnough)
TAXONOMY There are a few nymphs in my collection which are very doubt
fully being referred to Pseudocloeon punctiventris. These immatures
differ from Ide's description (1937 237) in that the median pale band
on the abdomen is quite distinct, and the tracheae in the gills are pro
minent in preserved material* MoDunnough described the speoies from




357
3*3 miles west of Grand Bay (June 2, 1940, H, H# H, and L* B*, nymphs)?
3*8 miles -west of Grand Bay (June 2, 1940, H* H* H, and L. B*, nymphs)?
3*5 miles south of Irvington (June 2# 1940, H* H* H* and L* B., nymphs)?
Bayou La Batro (June 2, 1940, H* H# H* and L B#, nymphs)? 5*6 miles
east of Irvington (June 3, 1940, H* II* H* and L, 3, nymphs and adults)?
3*2 miles south of Kushla (June 3, 1940, H* H, H* and L* B,, nymphs)?
Perdido creek about 2/ miles north of Florida state line (April 5, 1938,
H* H* H, and L* J. M*, nymphs? June 3, 1940, H, H, H, and L* B., nymphs).
Aoentrelia propinquus (Walsh)
TAXONOMfi Aoentrella propinquus -was recorded from Florida in my paper on
the Baetinae of Florida (1940c), and at that time some doubt was expressed
as to the validity of the identification? this doubt is still present. I
have been unable to obtain authentically identified specimens from any
source, and have seen none which seem to resemble the description of pro
pinquus more olosely than do the Florida insects*
In 1862, Walsh described Cloe vioina ? Hagen? however, this proved
not to be the vioina of Hagen, and in 1863 Walsh substituted the name
propinquus for viclna. In 1871 Eaton transferred propinquus to Baetis
and in 1885, he redesoribed the species briefly in his monograph* MoDun-
nough, in 1925, examined the type series in the Museum of Comparative Zoology,
selected a lectotype, and suggested that dardanus might be a synonym of
of Propinqups. The former species was treated by Traver in 1935 although
she mentioned the -possibility of synonymy* Traver recorded the speoies
[as Aoentrella propinquus (?) Vifalsh] in her paper on "Mayflies of the
Southeastern States" (1937:83) and briefly described the male and female


412
not a single specimen could be found there. The density of the nymphs in
this stream is indicated by the fact that in one sweep of the dip net
through the moss, sixty-seven nymphs were taken.
In May, 1940, the Wakulla Springs run was examined, and over a period
of about one hour ten nymphs were collected. This stream, as is usual
with spring runs, has dense growths of Vallisneria both in the slow ourrent
of the shore region and in the deeper more swiftly moving central part.
The river is fairly wide perhaps seventy-five yards. The bottom of the
stream is sandy but soft, somewhat limy. As an indication of high alkalin
ity, many Goniobasis were taken in the dip net, and on the bottom Ampularia
were very numerous. Collections could b6 made only near shore beoause the
river becomes deep very rapidly; even t iough all types of situations in
this region were examined, C. rubroplotum nymphs were found only on eel
grass.
Other streams from which nymphs of rubropiotum have been collected
are all derived from swamps, have tinted waters, are slow flowing, and
usually have much vegetation. Fever have the immatures been found other
than in protected plaoes, and these havens were always in vegetation.
The range of the various types of streams in which the nymphs live
does not seem to be limited by pH, for individuals have been found to
proceed well in either basic or acidic water. Temperatures in the western
part of the state fall to a rather low level during the winter and this
would seem to interfer with emergence, but, from a study of nymphal material,
suoh does not seem to be the oase unless it be oorsidered that those in
dividuals which are ready to emerge have their metabolic processes suffi
ciently depressed for a short time during cold snaps to allow them to live


16
the incisor and molar areas there is a small structure called the lacinia
mobilis, the function of whioh is unknown.* This structure has been inter
preted by some as a mandibular palp and a prostheca, but according to
Crampton it cannot represent a true palp* This author has suggested that
the mandibles of mayflies in some respects approach those found in the
Crustacea. Attached as lateral lobes of the hypopharycs, are a pair of super
linguae* Supsrlinguae are best developed in apterygote insects and in some
of the more primitive members of the Pterygota. The galea, lacinia, stipes,
and palpifer are fused in the maxillae of all modem mayflies, and form a
structure called the galea-lacinia* In some of the more primitive genera
it is though that & line of separation can be seen between the galea and
lacinia* On the whole, the maxillae of mayflies must be considered as rather
specialized*
The primitive condition of the tarsus of adult pterygote insects is
thought to be five-segmented; tarsi having fewer than five segments have
probably been specialized by the loss of or fusion of some of the segments*
In the adults of some of the more primitive mayfly generea, the tarsi are
composed of five freely movable segments, but in most mayflies there is a
certain degree of fusion* The legs, therefore, cannot be used as reliable
indicators of phylogenetic position of the Ephemeroptera among the other
insects*
The gills of mayfly nymphs are thought to be homologous with abdominal
legs appendages which have been modified for respiratory purposes. Snod
grass states that there is no question but that the gills arise from limb-
libs rudiments of the embryo, and that their structure and musculature suggest
that they are parts at least of true abdominal appendages* The most primi-


435
marked and can be identified with the naked eye among Florida material,
since it is the only Pseudocloeon found in this region in which the venter
of the terminal abdominal segments is deep red-brown*
DISTRIBUTION: P. bimaoulatus is the only Pseudocloeon occurring west of
the Apalachicola river* Thi3 fact plus the similarity in banding of the
caudal filaments hints that bimaoulatus may be synonymous with P punoti-
veneris, which is limited to the east side of the river* Since the two
areas are mutually exclusive and the two nymphs are so similar, except in
maculation, the identification must remain in question until male adults of
punctiventris are secured.
Nymphs are known from various streams throughout west Florida, west of
the Apalachicola river, into Mobile county, Alabama and northward into
Escambia county in the latter state* Over all of west Florida and southern
Alabama, the speoies is fairly common, and may be found in nearly all per
manently flowing streams* From its distribution, it would seem that bi-
maculatus is endemic to the western portion of Florida and the southern
part of Alabama, and is somewhat confined to the coastal area. Collections
from more northerly localities in Alabama did not include a single specimen
of P, bimaoulatus* (See sn*-/* s.).
ECOLOGY* The sand-bottom streams of the western part of Florida all support
populations of P. bimaoulatus, and in these streams it is much more common
than are its kindred species of the more eastern regions* Particularly
abundant in those streams with rather dense growths of eel grass, the nymphs
in some are second in abundance only to Baetis species* In the creeks, the
nymphs live on the Yallisneria vAiere the water is swiftest, but can also be
found in shallower, more slowly flowing water. Some of the streams along


150
August 20, 1938, W. M. MoLane, adults)* Lake Geneva (June 8, 1938, Mrs.
W. G. Carver, adults; June 25, 1938, L. B*,adults; July 2, 1938, L. B.,
adults; August 20, 1938, H* H* Hobbs, adults). Highlands Co. Childs
Crossing (August 11, 1938, T. H. Hubbell and J. J. Friauf, adults);
Sebring (May 12, 1939, F. N. Y., adults); Lake Co. - Beekman Lake (May
25, 1933, J. S. R. and A* F. Carr, nymphs); Sellars Lake (May 25, 1933,
J. S* R. and A. F. Carr, nymphs); Ifeiatilla (October 1* 1938, A. F. Carr,
adults). Marion Co. Swim Pond in Ocala National Forest (February 28,
1938, J. S. R., nymphs); Lake Bryant (April 16, 1938, J. S. R., nymphs);
near Eureka (September 7, 1938, T. H. Hubbell and J. J. Friauf, adults);
Juniper Springs (September 4, 1938, T* H Hubbell and J. J. Friauf, adults).
Orange Co. 1'inter Park (June 5, 1939, N. Marshall, adults). Osceola
Co* East Tohopekallga Lake (August 7, 1939, R. Harmon, adults). Polk
Co. Aubumdale (June 8, 1939, W. K. Smith, adults); Lakeland (July
26, 1938, L. J. M., adults; Sept. 8, 1939, A* F. and M. Carr, adults)
Winter Haven (July 25, 1938, A. C. Chable, adults; April 12, 1939, A. C.
Chable, adults; April 15, 1939, 0. E. Frye, adults; September 1, 1940,
A. C. Chable, adults; November 2, 1940, E* Shuls, adult). Putnam Co.
Sunnyside Beaoh (July 23, 1938, W* A* Carver, adults).


383
nymphs have been taken at only a single locality, the Santa Fe river*
In the Santa Fe river, the numbers of immatures fluctuates greatly
from one time to another, but the actual number of individuals is never
as great as that of spinosug with which interoalaris is associated* Both
speoies inhabit the eel grass, Sagittaria, eto* in the swiftest water, but
the interoalaris nymphs congregrate in more rapid parts in greater numbers
than do those of spinosus, and in the slower areas the ratio of intercalarte
to spinosus is reversed*
There are never large concentrations of nymphs in the sand-bottom streams
and frequently, even though other speoies of Baetls were fairly common ,
only one or two specimens of interoalaris were taken* The nymphs inhabit
the vegetation and debris wherever the water is permanently flowing* If
there is debris in the middle of the stream, the nymphs will more likely
be found there in greater numbers than near the shore* The oreeks in
Gadsden county frequenly have exposed roots of terrestrial plants which
are washed by rather rapidly flowing water; EU interoalaris nymphs can
usually be taken from them* Submerged logs in the swifter waters are also
productive situations if interoalaris inhabits the stream; however, ex
amination of such logs is a rather arduous task and less profitable than
root collecting*
The sise of the stream evidently has no bearing on the presenoe or
absence of nymphs, since the insects have been found in brooks no wider
than three feet and not much over three inches in depth, in creeks, and in
rivers* In the smallest streams there was no vegetation, and the nymphs
inhabited debris lodged in the stream bed* One small creek, about three
or four inches in depth, had its bottom covered with a thin growth of algae,


375
L. B*, nymphs); Crestview (December 12 1937, L. B*, nymphs)* Shoal river
(December 12, 1937, L. B., nymphs)* Santa Rosa Co* (4.8 miles north
of Navarre, June 1, 1940, H, H, H, and L. B., nymphs). Sumter Co. 2
miles north of Bushnell (March 27, 1938, L. B., nymphs); 1 mile north of
Sumter county line (March 27, 1938, L. B., nymphs). Taylor Co. Fen-
holloway river (March 18, 1939, J* S* R., H* H., F. N. Y,, L, B*, nymphs).
Wakulla Springs run (May 29, 1940, H* H, H, and L. B., nymphs). Walton
Co. 1 mile -west of Walton county line (June 7, 1938, L, B., nymphs); 2.1
mile3 west of Walton county line (May 31, 1940, L. B., nymphs); 5.4 miles
west of Walton county line (May 31, 1940, L. 3., nymphs); 10.6 miles west
of Walton county line (May 31, 1940, L. B., nymphs); 15.8 miles west of
Ebro (June 7, 1938, L. B, nymphs); 2.6 miles west of Freeport (June 7, 1938,
L. B., nymphs); *8 miles west of Portland (April 3, 1938, H* H, H. and L.
J, M., nymphs); 6.7 miles west of Portland (June 7, 1938, L. B., nymphs;
May 31, 1940, Jv. B.# nymphs); 9.6 miles west of Portland (May 31, 1940,
L. B., nymphs; June 7, 1938, L. B., nymphs). Washington Co. Holmes
creek (December 11, 1937, L. B., nymphs; April 2, 1938, H. H, H. and L. J.,
M., nymphs; June 9, 1938, 1. B., nymphs; July 2, 1939, L. J* M. and L. B.
nymphs).
Baetis australis Traver
TAXONOMYi Baetis australis was described from North Carolina in 1932 and
in 1936 was redesoribed by Traver in "The Biology of Mayflies." The occur
rence of the species in Florida was recorded by me in 1940, but nothing was
added to the taxonomic knowledge of the species. Morphologically, the male
is distinct from all other Baetis adults, and can be easily separated from


82
241
25 (24)
25
26 (25)
26
27 (15)
27'
28 (27)
28
lets attaching CuA to hind margin. (See fig* 31).
(Siphlonurinae) isonychia (25)
Cul two to four in number, free basally, not as above (see fig,
32),
(Metretoplnae ) Siphloplecton speciosura
Venation almost colorless.
Venation dark.
fore tibiae wholly dark.
(26)
Isonychia sp, B
Isonychia perdido
fore tibiae pale in the middle and dark at each end.
Isonychia pietiges
Hind wings present.
(20)
Hind wings absent*
(38)
Fore wings with numerous costal cross veins before the bullaj
in female, costal margin brownish (see fig. 33). Moderate number
of cross veins present in hind wings.
Callibaetis (29)
Fore wings without costal cross veins before the bulla (see
fig. 15), Ho cross veins in hind 'wings (seo fig. 16).
(31)
29 (28)
<5 Intercalarles in mid-posterior margin of forewing occur
singly. Abdominal segments two six whitish hyaline with


186
that the spur ms now quite short and insignificant This evidence would
seem to indicate that the size of this struetur varies from instar to
instar* In addition, it has been found that nymphs in the last instar
invariably have short tibial spurs, while those in earlier instars have
spurs varying in length from one-half to three-fourths or more the length
of the tarsus.
By use of the structure of the forceps or styliger plate, the genus can
be divided into two distinct groups* A further subdivision into four
groups has been made on the basis of the peeularities in the structure of
the penes. The Florida species seem to fall into two different groups,
but since material lias not been available for study which shows the vari
ous genitalia patterns, they will not be classified according to this
plan. Apparently one species belongs to the sicca group, another to the
albomanicata, the other species are known only from nymphs or females.
The nymphs of Isonychia, likewise, may be grouped those with a
brown band across the antennae and those lacking the band. Both of
these forms occur in Florida but further subdivision must remain in question
until adults are reared.
Isonychia is an Holarctic genus and is rather widely distributed in
the TTearctic region. Travers work in Forth Carolina showed that in
the southeast this is one of the important genera as far as speciafcion
of mayflies is concerned, for, of the twenty-six described species, six
teen occur in this regi n. The two other species from Florida bring
this total to eighteen.
In Florida Isonychia is confined to the northern part of the state,
and does not appear east of the Suwannee river drainage system. Westwards


59
They are clear, cool, and moderately flowing with rather dense growths of
vegetation in the stream proper. Vegetation is composed ohiefly of
Vallisneria, Sagittaria, Nais, Isnardia, mosses, many algae, eto. which
in the shallower zones form dense mats completely covering the floor of the
stream. The water may be oolorless if the source is confined to springs,
but if swamp waters also contribute to the stream the water may be tinged
with brown* Many of these rivers have sand-bottoms, and there may be thick
deposits of silt in the quieter shallow zones. Leaf drift and other debris
becomes entangled in fallen trees and other catch-alls, and such debris
forms an important habitat for many mayflies and other organisms. In some
of the rivers, there are outcrops of limestone, and in the Santa Fe river,
specifically, there are many loose rocks which are of great importance as
habitats for aquatic organisms. The depth of these streams varies from
three feet to twenty feet or more, the width from seventy-five to three
hundred feet, Faunistically, this type of stream is the richest found
within the boundaries of Florida, both in number of individuals and in
species. Carr (1940 25) states that Optimum conditions [for fluvial
organisms] apparently exist in those rivers which run over ledges of ex
posed limestone, or which receive most of their water from calcareous springs.
Ditches and Puddles
(l) Roadside ditches: These are extremely rich situations for aquatio
organisms if there is permanently standing water in them. The ditches
are quite varied in appearance but the fauna is fairly constant. In some
of them, there are dense growthB of Pontederia which is the predominant
plant. The water is shallow in the zone of pickrel weed, but may become


23
Family Baetldae
Subfamily Ametropinae
" ~ Metretopinae*
" Siphlonurlnae*
" Leptophlebiinae*
" Baetiacinae*
" Epheme re11inae*
Caeninao*
" Baetinae*
Ulmers key (1933) to the Ephemeroptera of the world lists three sub
orders, Ephemeroidea, Baatoidea, and Keptagenioidea and these in turn are
divided into fourteen families* These families of Ulmer* however* in some
oases* do not coincide with the subfamilies of Needham and Traver* Spieth*
also in 1933* used superfamilies in his discussion of the phylogeny of
North American mayflies, and included his genera under the following: Super-
family Siphlonuroidea* including the families Siphlonuridae* Heptageniidae*
Baetidaej Superfamily Ephemeroidea, including the families Leptophlebidae,
Sphemeridaa, Ephemerellidaej Superfamily Caenoidea, including the family
Caenidae} and Superfamily Baetiscoidea* including the family Baetiscidae*
Chernova recently (1938) described a new family of mayflies from Russia* but
I have been unable to secure a copy of this work and can give no information
about the groqp*
The usage of the terms suborder, superfemily, family* and subfamily as
higher categories appears to be merely a matter of convenience subject to
the whims of eaoh particular worker* However* consistency in usage would
seem to be desirable, and whether the tern family or subfamily is used to


17
ti ve of the modern mayfly genera bear ills on the first seven abdominal
segments* and the earliest fossils known had these structures on the first
nine segments. The retention of these abdominal structures appears to in
dicate primitivenese, even though they are present in highly modified and
variable forms.
A consideration of the characters discussed above will also show that
mayflies, while generalized in many respects, are at the same time highly
specialized in oertain features* As Needham (1935s 207-208) has said, "The
group as a.whole, while retaining a good many primitive characters, has
gone a long way in specializing on lines of its oiwn There arc no very
primitive mayflies. There is no one genus or species that can be set down
as nearest to the ancestral form in all particulars. The lines run criss
cross here as elsewhere, and do not lend themselves to a serial arrangement."
One of the principle modifications and specializations undergone by
the wings has been the oephalization of the flight mechanism, with relative
enlargement of the fore wings and corresponding reduction of the hind wings
until, in scsie genera, the latter have entirely disappeared. In the specializ
ed genera venation tends to become reduced, and oertain of the longitudinal
veins become detached and may even be shifted at their bases and reattached.
Paralleling this modification of the longitudinal veins, there is a tendency
toward reduotion in the number of cross veins in the fore wings, until
in tiie highly specialized genera they may be almost completely absent. At
the same time that the cross veins are becoming reduced in number, a series
of marginal veinlets develops, occupying the interspaces between the longi
tudinal veins. The presence of these veinlets is a mark of greater specia
lization than the irregular marginal network (the remains of the archediotyon)


222
as late as 7 30 p. m. during April* while in October transformation
occurred between 6s20 and 700 p* m.
Subimaginal life lasts twelve to fourteen hours; the male imago
lives a day longer, and the female may sometimes live as much as two or
three days after this last molt.
I have never observed mating flights of this species. Another species
is treated briefly by Morgan (1913 392)t "Mating flights of Leptophlebia
praepedita have been seen in the middle of a sunny forenoon, and at two,
four and five oclock of bright afternoons in May and June* None of these
rose higher than IS feet and two of the swarms did not fly mere than six
feet above the ground. One entire swarm which was captured contained
forty males and one female."
DERIVATION OF THE SPECIES The much greater development of Paraleptophle-
bia in more northern and mountainous areas, and the presence there of
species which are most closely related to volitans indioates that the
latter is a continental form which has recently migrated into Florida*
probably accompanying other Leptophlebines. It is no better established
than Kabrophlebiodes or Blasturus, but there are several more records
for this species than for the other two. Invasion of Florida probably
occurred through the drainage of the Chattaehoochee and Flint rivers.
LOCALITY RECORDS Alachua Co. 1 mile west of Lake Newnan (May 11,
1937, L. B., nymphs and adults; January 8, 1938, L. B., nymphs); Hatchet
creek (March 23, 1938, L. B., adults; April 2, 1938, L. B., adults;
April 18, 1938, L. B., adults; May 5, 1938, L. B., adults; July 9, 1938,
L. B., adults; March 22, 1939, L. B., April 1, 1939, L. B., adults;
April 5, 1939, L. B., adults; April 13, 1939, L. B., adults; May 6,


265
in those ecologically available streams of the panhandle*
LOCALITY RECORDS: Escambia Co*, Alabama Perdido creek about 2/3 miles
north of Florida state line (June 3, 1940, H* H H. and L* 3*, nymphs and
adults)* Gadsden Co*, Florida 4 l/2 miles south of River Junction
(March 17, 1939, J. S* R*, H* H* H, F* II* Y*, L* B., nymphs, imagos reared
March 29, 31, and April 3)* Liberty Co* Hbsford (March 17, 1939, J* S. R.,
H H* E,, F. N* Y*, L. B*, nymphs)* Okaloosa Co* -- 5 miles west of Walton
county line (June 7, 1938, H* H* H*, F* N* Y*, L B*, nymphs)? Niceville
(June 7, 1938, H* H* E*, F* N* Y*, L. B., nymphs; November 6, 1938, L* 3*,
nymphs). Santa Rosa Co* 2 miles west of Milton (April 4, 1938, H. H. H*
and L J. M., nymphs). Walton Co* Freeport (April 2, 1938, E. E* H. and
L* J* M*, nymphs); 5*4 miles west of Washington Co* line (May 31, 1940,
H. E* H. and L. B., nymphs)*


83
2*
3 (2)
3
4 (3)
4
5 (4)
5'
from above head (see fig 1). Sills present on segments 1-7,
rudimentary on segment lj no protective cohering; feathery
appearance.
(3)
mandibles with no tusk that is visible from above head. (See
fig 2). Sills present on segments 1-7, or they may be absent from
one or more of these segments.
Head with a conspicuous frontal prooess.
Ephemerinae
(8)
(4)
Front of head rounded, without such a process.
(Campsurinae ) Caxapsurus insert us
Elevated frontal process rounded or truncate (see fig.
ilexagemia
3).
(5)
Elevated frontal prooess bifid (see fig. 4).
Ephemera simulans
mandibular tusk strongly upcurved in outer hald. Large nymphs
body length of females 26-29 mm. ¡ of males 23-26 mm.
Frontal process broadly rounded to truncate. Stream inhabitants.
(6)
mandibular tusks more gently upcurved in otter half. Smaller
nymphs body length of females 20-26 mm. j of males 15-22 mm.
Frontal process conical to narrowly rounded. Lake inhabitants
(bilineata map occur in streams).
(7)


173
OREIANTHUS Traver
The unique mayflies belonging to this genus were described by Traver
in 1931, 1935, and 1937 as Qreianthus purpureus and "Qreianthus species
No* 1." A third specieB, described by Joly as Caenis maximus in 1871,
on the basis of nymphs from the Garonne River in France, has been assigned
tentatively to Qreianthus by Traver (1931i 108)* The relationships of
the genus are particularly Interesting, for "while the characteristics of
the adult definitely ally it with the Ephemeridae, the nymphal characters
very closely parallel those of the Caeninae* However, it has been consider
ed that the nymphal characters are secondary adaptations, and that the wing
venation, which is fundamentally of the Ephemeridae type, indicates the
true relationships# McDunnoughs genus. Neoephemera, has been place by
Traver in a separate subfamily, Neoephemerlnae, along with Qreianthus*
In the United States, this genus is known to occur in North Carolina,
Tennessee, Georgia, and Florida in the Valley and Ridge, Blue Ridge, and
Piedmont provinces and the Coastal Plain*
Phylogenetically, Qreianthus is rather difficult to place* In 1932,
Traver suggested that "The general appearance of the imago, other than
the venation, is as dose to certain members of the subfamily Baetinae
as to the Ephemerinae, and I think it more olosely allied to the foimer
than to the latter group." However, in subsequent publications, she
has definitely placed Qreianthus with the Ephemeridae* Possibly, even
though the nymph is very highly specialized, the genus may oocupy the same
type of intermediate position with regard to the Ephemeridae and Baetidae
that Isonychia occupies with regard to the Baetidae and Heptageniidae.
More llkBly, it represents still a fourth, and entirely separate, family


305
There are large numbers of insects, many of them predators, living in
the ponds along with small fish and the other usual organisms of the
pond biocoenosis, In the slowly flowing parts of streams, the other
mayflies found inolude Stenonema amithae, Baetis spinosus, B spiethi,
Callibaetis florldanus, C pretiosus, Centroptilv~i vlridooularis, and
more rarely Paraleptophlebia volitans, Habrophleblodes betteni, Blasturus
intermedius, and Ephemerella trilineata,
SEASONS* There is no definite season for adults of C* diminuta in Florida,
I have records of adults for all months of the year and there are no
olear-cut broods. The only date record that I can find in the literature
for the species is one of McDunnough's **> August 20, Gravenhurst, Ontario*
in this northern region, C, diminuta must be seasonal, in fact it could
not be otherwise for the ponds in which it lives are frozen completely
over during the winter months. However, even in Florida, though emer
gence occurs the year around, this species is to some extent limited by
the temperature,for I have observed on a number of occasions that during
a cold spell emergence comes to a standstill. As soon as there is a change
in the weather and the shore zone warms sufficiently, subimagos begin rising.
Collections at a light on warn nights during the winter time indicate
that the rate of emergence is somewhat less than during the summer, but,
even so, the number is large. Lighting in a particular area on consecu
tive nights frequently does not yield the same results, although lighting
conditions may be approximately the same. This may be due to emergence
of different broods from the same pond, but sinoe there is obviously so
much overlapping in generations, the existence of distinct broods is
somewhat doubtful.


24
designate these categories is a matter of choice. The taxonomic system,
i. e. the higher categories, set up by Needham and Traver appears to be
adequate in the present status of our knowledge.
As far as the inclusion of genera within the families and subfamilies
is concerned, muoh more phylogenetic study is necessary before the positions
of several of these groups can be satisfactorily determined. Certain genera
exhibit characteristics which would plaoe them in either of two subfamilies,
and in such cases it is desirable to indicate this overlapping in discussions
of these genera. In reality, there are no genera of North American mayflies
which cainot be placed rather definitely in the higher categories, except
perhaps Isonychia, which has been included both in the Heptageniidae and
Bastidae* In this paper, Isonychia is considered as blonging to the
Baetidae, but the placement is debatable.
Ulmers 1933 key to the Ephemeroptera of the world included one hundred
fifteen genera, and sinoe the publication of this work several generic changes
and additions have been made. At present, forty-nine genera are recognized
as oeourrlng in North America, north of Mexico. Sinoe the publication of
"The Biology of Mayflies", Aoentrelia has been re-erected, and Oligoneuria
has been discovered in the drainage of the Mississippi*
When Traver wrote her taxonomic review of the mayflies of North America
in 1935, she included five hundred seven species. Since the publication
of tide work, forty-two additional speoies have been described from the
region. There are still numerous areas on the North American continent
which have barely been touched, and when these are finally worked many more
undescribed species will, without doubt, be discovered*


159
cribed them in her 1931 paper under the designations Hexagenia nymph No*
4 and Hexagenia nymph No* 5*
DISTRIBUTION* Hexagenia orlando, if suoh it is, has been taken from as
far south as Hillsborough oounty and as far west as Leon county; weewa
replaces it further west. Since Orlando, Florida is the type locality of
H* orlando, I have tried to secure specimens from this region, but all at
tempts produced only H* limnophila, the lake species* H* orlando is a
stream form but apparently there are very few streams in the Orlando area,
at least constantly flawing ones* The nearest stream of this type to
Orlando seems to be the Wekiva river, which is about fourteen miles distant.
In addition to Orlando, Traver has recorded the species from Kissimmee,
Florida; Spring Creek, near Decatur, Georgia; and Tuscaloosa, Alabama, (see m^pz).
ECOLOGY* The ecological relationships of H. orlando are identical with
those of H* weewa* In January, 1940, nymphs of a burrowing species were
found in Hogtown Creek, about one mile west of Gainesville* Previously,
I had not taken burrowing nymphs nearer than the Santa Fe River* Only
forty-five of the insects were collected in about three hours, for they
were quite soaroe* These were brought into the laboratory where they
were put into a pan with a layer of silt about one-half inch in depth.
A few days later, I returned to the creek and collected twenty more inma
turos which were placed in cages submerged in the stream; however, Hog
town creek became heavily contaminated from some unknown source and nearly
all the insects as well as fish, eto* in the stream were killed* From the
insects kept in the laboratory two males were reared whioh are very similar
to the adult which Traver sent me.
The nymphs proved to be very hardy under laboratory conditions* At


253
Iraver* s study of the mayfly fauna of Forth Carolina, she did not take
a siade specimen of vibrans, but did take a new speoies which she de
signated H* pusilla.
This species is either very elusive or very rare in Florida,for during
the entire period of my research, only two nymphs have been collected
L'y identification of the nymphs is based on a comparative study made with
a nymph taken from a stream in the mountains of north Georgia where, at
the same time, two male imagos were also captured Color pattern, gill
structure, mouthparts, etc. correspond very closely in the two groups of
nymphs (5ee l'naT ^'
ECOLOGY: As far as I can determine, there has been nothing written con
cerning the eoology of the Forth American species of Habrophlebia end
very little can be written about the Florida nymphs. The first immature
was taken in December from a small, sand-bottom stream in northwest Florida
The bottom of the creek was covered with muoh leaf drift, and in places
was quite silty. It was from among the leaf debris that the nymph was
taken. The second nymph was not collected by me and there is little
information about its habitat except that it was a swiftly flowing, Eand-
bottom stream.
Associates in the leaf drift of the December nymph irere Blasturus
intermedins, Babrophlebiodes brunneipennis, Paraleptophlebia volitans,
Stenonema smithae, and Ilexagenia weewa. Daraselflies, dragonflies, stone-
flies and the usual associates of the sand-silt stream bed were also pre
sort. This stream whs definitely acidic, having a. pH of 6*2.
SEASCFS: The December nymph is somewhat better than half grownj the April
specimen is last instar. No conclusions can be drawn from such scanty


203
distributed throughout this region. Its phylogenetic position is stated
in the discussion of the relationships of Blast urus, Leptophlebia, and
Paraleptophlebia given under the last-named genus. Spieth (1933*345),
before he considered Blasturus to be a paid; of the genus Leptophlebia,
thought that it was probably the most primitive genus of the family Lent a-
phlebidae (considered here as the Leptophlebiinae), and that Blasturus
and Leptophlebia presented a rather close affinity to each other. "In
dications that they all [includes Choroterpes and Thraulus] represent
primitive branches of a major division of the Ephemerida are* (1) the
fairly primitive condition of the wings, especially those of Blasturus;
(2) the simple form of double gill consisting of two foliacsous lamellae
without such special modifications as are found in the Heptageniidae and
Baetidae branches; and (3) the 3-Jointed forceps, lacking any indications
of the basal articulation commonly found elsewhere in the order."
Blasturus intermedius Traver
TAXONOMY* Since Eatons work, very few ephemerids have been described
from the subimago; unless the species is quite distinct from all others,
subimaginal descriptions may tend to be misleading and may frequently cause
misinterpretations. However, Traver (1932* 136-137) broke with custom
and set up a subimago as the holotype of B* intermedius, figuring the
genitalia and various nymphal structures. By 1936, male imagos had been
reared and thespeoies was found to be quite distinct from all others in
the genus,except B. granis, on the basis of genitalial differences. Miss
Traver has designated the genitalia of this oomplex as the "distinctive
'scarf' type" of penes and in her key to the species, separates intermedius


100
ness from on en to the other. Then a large number of nymphs were put in
the water, and after a short time it was found that nearly all of the
specimens were att ched to the lower surface of the upper brick with their
dorsal side downward, and a large majority of the specimens were in that
portion of the wedge-shaped space where their baoks came in contact with the
brick below." The same author shewed that the tropism is so strong that
only when the water in which the nymphs live was heated to forty-five degrees
centigrade did the insects leave the stones to which they were clinging,
and this happened only after the nymphs had been overcome by the heat.
Reaction to light is also quite strong in Stenonema nymphs and they
will readily react to changes in intensity. The tropism is definitely
negative. A stone was placed on a white background in a dish of waterj in
the same dish, a stone was also introduced which had a dark background. A
series of nymphs were then released on the former stone} after a few hours,
nearly all nymphs had migrated to the darkened area where they remained
without any apparent desire to leave.
Vfodsedalek (1912b t 260), during his research on Palmen*s organ in
mayflies, found that the supposed reaction to light is in part a result
of orientation. "In their natural habitat they are always found clinging
to the under surfaces of small rocks, and this sam position is regularly
assumed by all normal ones in the aquaria of the laboratory. When a stone,
to which the specimens are attached is inverted in the water, the inseots
soon make for its under side, many of them doing this a.3 the stone iti being
turned over. This is also true of normal specimens in the dark-room, and
hence it is obvious that this tendenoy of the nymphs to cling to the lower
surfaces of rookB, with their dorsal side downward, is not due entirely


195
Carolina which Traver found to be twenty-two to twenty-six and thirty-
one hours respectively.
The mating flights of Isonyohia have not been observed, and there are
only a few scattered notes describing the mating flights of some of the
species of this genus. Concerning 1 sadleri, Traver wrote (1937* 59)
"Often they danced high in the airj again, individuals as well as mating
oouples drifted down almost to stream level. They were strong, tireless
dancers, the first to appear and the last to leave the scene of festivity."
Clemens ^,1917) has discussed the emergence, the subimaginal period,
tne imaginal stage, ana the mating flight of I* albomanioata. Although
the nymphal emergence is probably different in the Florida species beoause
of differences in habitat, the mating flight is most likely very similar.
DERIVATION OF THE SPECIES* I* perdido.is confined to the western part
of Florida and may be endemic to tnis region, but until adults are secured
this statement must be made with reservations. Also because of the lack
of imagos for study, the affinities of I. perdido must remain in question,
but 3ome leads are presented by the subimagos, which in genitalia super
ficially resemble the sicca group. Very likely closely related species
will be found in Alabama and Georgia, all having come from an ancestral
stock which originally inhabited the mountainous streams of the Appalachians.
Those streams draining the foothills may well have served as pathways for
the dispersal of this ancestral species.
LOCALITY RECORDS*Bay Co. 16.8 miles north of Panama City (June 8, 1938,
H. H. H., F N, Y., L. B., nymphs). Gadsden Co0 4 l/2 miles south of
River Junotion (March 17, 1939, L. B., nymphs). JackBon Co. 12.2 miles
southeast of Marianna (June 9, 1938, H. H. H., F. N. Y., L. B., nymphs,).


156
the silt In streams other ephemerid associates of H. weewa are the
same as those listed for "Oreianthus sp No* 1"*
SEASONS The specimens Needham collected were taken on April 8, 1927.
I have adults captured in April, March, June, July, and August as well
as some specimens which emerged in the laboratory during September. A
single nymph, which is rather close to maturity, was oolleoted. in late
November and would probably have emerged early the following spring. I
have little doubt but that E. woewa is a seasonal species emerging over
a period of about eight months# There is definite brooding, but I have
been undble to obtain further data about this. Nymphs collected at var
ious times of the year fall into distinct size groups and there is much
overlapping of young with old nymphs.
HABITS: The habits of E. wsem are much like those of H. limnophila.
LIFE HISTORY; It is likely that the developmental period of K. weewa
is one year, although there is little definite information to support
this statement* There is fairly good evidence to indicate that H. orlando
needs but one year to complete its life history,and because of the close
similarity between weewa and orlando, both structurally and ecologically,
it would seem probable that weewa also can develop within a year.
Subimagos, in the laboratory, emerge in late afternoon, but I obser
ved a single female emerge in the field about 10*00 a. m* After a resting
period of fourteen to twenty hours, the final molt ocours, and this is,
of oours, followed by mating if conditions are propitious.
I have observed only a single mating flight made up of a small swarm
of about fifty to seventy-five males. The flight took place just at dusk,
the sun had set and the adults could barely be seen against the darkening


419
from the type localities, others have two or three looality records,
but these records do show that the genus is widely distributed over the
eastern portion of North .America Not a single record of Pseudocloeon
has been published to indicate that it is distributed in the Rockies or
west of them In fact, there are no records frcm the central United States
and only a few from eastern Alberta % the most westerly known Pseudocloeon
that has been taken south of Alberta is from Austin Texas
Previously, the genus was unknown from the Coastal Plain (unless
P veteris, taken at the Fall Line in Texas was collected from the Coastal
Plain side of the line), but the genus has been found to be rather widely
distributed through Florida where there are permanently flowing streams
Spieth concluded from his study of the "Phylogeny of Same Mayfly
Genera" that Baetis and Pseudocloeon were closely related, and the mere
fact that Pseudocloeon lacks the metathoracie wings did not indicate to
him a close relationship to other genera which lack these wings. He stated,
"The genus Pseudocloeon is like Baetis in every item of nymphal and adult
structure considered here [venation, genitalia, mouthparts, and gills],
except that the adult lacks hind wings and the nymph has only two caudal
setae McDunnough has established a genus Eeterooloeon, for those species
in which the hind wings are present but are reduced to a mere thread
Considering wing characters alone, a graded series can be found which ex
tends from the condition found in Baetis parvus to that found in Pseudo
cloeon... . It is possible that even Pseudocloeon [as well as Acentrella
and Heterooloeon] should be considered part of the genus Baetis, comparable
with the short winged forms known among Drosophila, leaf hoppers, beetles,
parasitic hymenoptera, gall wasps, etc. Each of the types of reduced wings


26
dorsal surface." (Spieth, 1933; 60).
The triadic type of branching is also a characteristic feature of
mayfly venation. When a longitudinal vein forks, there is interpolated
between the two branches a third vein of opposite position, which does
not reach the base of the fork. For example, the anterior media, a convex
vein, forms a fork just beyond the middle of the wing (called the outer
fork [OF] of the radius by Needham). The two branches of this fork are
convex} however, the intercalary vein lying between the two branches
is oono&ve. This system of fluting is primarily an adaptation for radial
strengthening of the wing, and the cross veins serve chiefly to hold the
ridges and furrows in place. In the more specialised mayflies, which have
small hind wings or none at all, there is a decrease in the number of
cross veins while in those speoies which have large wings with prominent
fluting, the oross- venation is well developed. This system can be seen
to reach its maximum in Ephoron in which there are several hundred cross
veins in the fore wings*
The origin of the various wing veins lias been studied principally by
proponents of the Needham system* hr* Ann Morgan (1912) conducted a
rather intensive investigation into the origin of the definitive adult
venation} but in the light of further research by Tillyard and others,
some of her results have been found to be erroneous. One of the most
outstanding pointB of disagreement is that while Morgan interpreted the
radial sector and media in the same manner that Needham had interpreted them
in Odonata, showing Rs crossing the media, more recent studies lend no
support to this interpretation. There is a complete review of wing traohea-
tion in "The SicJogy of Mayflies*"


¡39S
creek, and of these some have been successfully reared to adults.
Hatchet creek is a sand-bottom stream, rather deep in places but,
for the most part, a shallow, moderately rapid creek. The depth varies from
six or seven feet to as little as six inches in the more swiftly flowing
portions. Hear the shore, there are dense growths of parrots feather
(Myriophyllum sp.), and in the stream proper there are clumps of Potamo
getn, Juncus repans, Globifera umbrosa, and some Fontinalis. Hear the
shore in quieter areas there are rather large accumulations of leaf drift,
while the stream is margined with various grasses which are partially in
the water. It is in the latter situation that the nymphs wore foundj however,
two nymphs have been collected from the leaf drift* The insects live near
the base of the plant stems where there is a silty accumulation and very
little flow.
In the other stream near Gainesville mentioned above conditions are
somewhat different from those of Hatchet creek, for it is considerably
smaller. It definitely falls into the sand-bottom oategory, is about three
feet wide and one foot deep, and in plaoes becomes wider and shallower.
In these shallower parts where the current is more rapid, there are growths
of Juncus repans, while in the more slowly flowing, deeper regions one of
the mosses beoames predominant. The nymphs of £ virldocularis were found
in greater numbers in this latter plant, which is thoroughly covered with
a heavy deposit of silt, than in any other stream in Florida. In the shallow
zones, a few nymphs were also found in the detritus which accumulated
between the projecting roots of large trees along the stream margin.
The condition of the Santa Fe River at Poe Springs has been described
previously. It is only in the most slowly flowing parts of the river that


338
this is given by Banks as the type locality of C. floridanus This
species is the only mayfly in Worth America which is known to inhabit brack
ish water. Eaton records a Cingalese Palingenia which inhabits an estuary
where the water "occasionally must be braoklsh." This same author also
reoords Cloeon dipterum and Caenis haltsrata from braokish-water streamlets
of Haraman-es-Salakin, Biskra (1895* 144).
In the standing waters of Florida, the only ephemerid associates of
C. floridanus are C. pretiosus and Caenis diminuta. Along the margins of
slowly flowing streams where C* f* minor may occasionally be found are also
Caenis diminuta, C. pretiosus, Ephemeralla trilineata, Paraleptophlebia
bradleyl, Blasturus intermedius, Baetis spiethi, B# spinosus, and Stenonema
smithae. The usual associates other than mayflies in the ponds and ditches
include Odonata larvae, Hemiptera, various water beetles, caddisflies, etc.
The adults of C. floridanus remain in a fairly moist situation, although
I did collect a fair series from a burnt-over field adjacent to one of the
canals in the Everglades. In the rock pits of south Florida, there are
very few or no bushes, bub there are relatively dense growths of grasses;
the mayfly adults remain hidden in the low vegetation until time for egg
laying. In one section of the Everglades, which was, in part, a cypress
swamp with emergent grasses scattered throughout the area, I collected some
ninety-odd mayflies by sweeping the low plants; apparently the adults
preferred remaining closer to the water than flying into the trees.
SEASONS* Throughout Florida, mergenoe of Callibaetis floridanus occurs
over the entire year. Records for adults of £ f* floridanus include only
the summer months and November and February; this is due entirely to lack
of collecting during the other months. There are imagos or mature nymphs of


3
there must be limitations to a book of this sort, and a certain number of
criticisms have been leveled at it, some quite unjustified Without a
shadow of a doubt, the book is extremely useful and lias stimulated interest
in this formerly much neglected order The greatest gap is found in the
taxonomic section, which deals almost entirely with the adult insects
The majority of species are described only as imagos, and many of these
only in the male sex, although sexual dimorphism is frequently exhibited
among tixe Ephemeroptera. Nevertheless, the collection of this huge amount
of data between two covers has greatly lightened the task of persons be
ginning a study of this fascinating group of insects
HISTORICAL REVIEW
The history of work on the Ephemeroptera was very thoroughly reviewed
by Morgan (1913), and a brief paragraph alloted to eaoh worker who had
contributed to a knowledge of the mayflies up to 1911 Needham in "The
Biology of Mayflies" briefly disoussed the earlier Ephemeropterists, but
did not attempt any detailed analysis of the present trends in this field.
A large part of the work on North American mayflies has been of a
taxonomic nature, but several important studies on morphology, ecology,
embryology, and life histories have been made Taking tip the account with
the year 1911, to which date Morgans summary extends, the following im
portant contributions deserve mention
J S. Needham published an important study of the genus llexagenia in
1920, dealing with taxonomic as well as ecological problems Taxonomic
studies by this author appeared occasionally from the years 1924-1932,
until his interest in the Odonata came to fully occupy his time However,


37
of species by high temperatures. His analysis of an Ontario stream in
terms of temperature is very interesting; but although no such tempera
ture studies have been made on Florida streams, Ides results are not
applicable to them because the temperature is uniform throughout the stream.
Iiis conclusions might also lead to the idea that the greatest number of
mayfly species should be found in the southern part of Forth America, where
higher temperatures occur throughout the year, but,as was pointed out above,
the reverse is true.
The rate of flow of water is also an important factor influencing
the distribution of mayflies, but even though there are numerous streams
in northwestern Florida which have a constant and fairly rapid movement,
many species wliioh occur in Forth Georgia and North Carolina are not found
in them. The interpunctatum complex of Gtenonsma is represented in Florida
by a single species, and this complex (perhaps even the same species that
occurs in Florida) also is found in the mountainous streams of North Caro
lina. Iron likewise is found in these North Carolina streams in identical
habitats with the Stenoneraa nymphs. Yet, for some unknown reason., ~;-"r
does not seem to be distributed south of the Atlanta region in Georgia.
The degree of tolerance may be greater in the Stenoneraa species, or per
haps there may be certain differences in feeding habits which would pre
vent the spread of Iron.
Habitats v/ithin Florida streams are apparently more limited in extent
and variety than in northern ones. A great many of the northern streams
*
N \v
are filled with rooks and pebbles, and this condition evidently affords
the optimum circumstances for great numbers of mayfly species. Combined
with the rocks are, of course, pools, vegetation, debris, and many other


84
-31
q
Map 12* Distribution of
Caenis diminuta and £ hilarisa
:
j *
0 s
Ti V
*..y ^
o
'Vi
\
i
\ 2 V
/ ft \
-/ ¡S
t 1
§ A
o r
0
diminuta
hilarls
H
&
* ,




SUMMARY
1. Four years have been spent in the study of the mayflies of Florida,
and during this period forty-seven species in twenty-three genera
were found. Of these, only five species were previously known from
the state.
2. An historical review of work on mayflies from 1911, the date to which
Morgan carried her summary, to the present is given.
S* The order Ephemeroptora is discussed, and a treatment of primitive
and specialized characters, the families of mayflies, the wing venation,
and taxonomic characters is included.
4* The Floridian mayfly fauna is compared with more northern and mountainous
faunae from the standpoints of taxonomy, comparative abundance, compara
tive ecology, and life history*
5. A discussion of the zoogeography and dispersal of mayflies is included.
It is pointed out that winds mar the earths surface, flight of adults,
floods, stream piracy, and high wind currents are probably the most
important disseminating factors.
6. The aquatic situations in Florida are classified and discussed. Cooke
has divided Florida into five regions based on the natural topography
of the state, and the distribution of mayflis bears out such a division.
7. A key to both adults and immatures is presented*
8. Each of the forty-seven species is treated from the standpoints of
taxonomy, distribution, ecology, seasons, habits, and life history, and
the derivation of the species and locality records are given*


428
there are undoubtedly other factors that must he taken into consideration,
and these may well be the recent origin of alachua, or temperature relations,
although I consider the latter factor a negligible one in the distribution
of North Florida mayflies*
LOCALITY RECORDS: Alachua Co. Campus, University of Florida (March 5,
1957, F* N* Y*, nymphsj July 31, 1938, L. B., adults; January 28, 1939,
L. B,,, nymphsj February 7, 1939, L. B., nymphs; March 23, 1939, L. B.,
adults and nymphs; April 12, 1939, L* B., 1939, L. B., adults; April 15,
1939, L. Bt adults; April 20, 1939, L. B., adults; June 23, 1939, L. B.,
adults; November 8, 1940, L. B., adults; November 22, 1940, L. B., adult 8)|
Hatchet creek (March 22, 1937, L* B., nymphs; April 1, 1939, L. B#, nymphs
and adults; April 13, 1939, L. B., nymphs and adults; May 6, 1939, L. B.,
adults; June 24, 1939, L. B,, adults; October 11, 1939, L* B., adults;
August 10, 1940, L* B,, nymphs; March 2, 1941, L. B., nymphs); Hogtown
creek (April 3, 1937, L* B., nymphsj April 28, 1937, L* B., nymphsj Septem
ber 25, 1937, L. B., nymphs; October 30, 1937, L. B., nymphs); Devils
Mill Hopper (October 25, 1937, S* Spur, nymphs; December 13, 1937, L. B.,
nymphsj March 5, 1938, L. B, nymphs); 2 l/2 miles west of Gainesville
(February 3, 1938, L. E., nymphsj March 18, 1940, L. B., nymphs and adults);
Santa Fe river (March 25, 1939, L. B., nymphs and adixlts); 20 miles north
of Gainesville (May 12, 1937, L* B., nymphs). Hamilton Co. 8.3 miles
south of Jasper (February 4, 1938, H* H. H., F. N. Y., L. B*, nymphs).
Hernando Co. -- southern county line (March 27, 1938, II. II. H., L. J. M*,
L. B., nymphs). Hillsborough Co. Six-mile creek (March 26, 1938, H. H. H,
L. J. M., L* B,, nymphs); Bell creek (March 26, 1938, H. B* H*, L. J.^I., L.
B, nymphs and adults); Little Fish^hawk creek (March 26, 1938, II* H. II,


277
are short and thiok, adapted for maintenance of these little nymphs in
swift water* The laws of apalaohloola are proportionately longer and thinner
than those of the former species, and this seems to be correlated with the
slower waters it inhabits and the consequently lessened tension on them*
The character may, however, be only an expression of habitat difference
and of no value taxonmically*
From the nymphal standpoint, deficiens and apalaohioola would seem
to be two of the more primitive species of Ephemerella were it not for the
loss of the maxillary palpi. However, the lack of any spinning on the body
of the nymphs, the presence of gills on segments three through seven, and
the lack of elytroid gill covers indicate that the serrata group, to which
defioien8 and apalaohioola belong, is most likely primitive*
DISTRIBUTION! The geographio distribution of E apalaohioola is very in
teresting because in only two localities does the species occur east of
the Apalaohioola river drainage* The first of these is a small stream about
ten miles north of Atlanta, Georgia,which drains into the Chattahooohee
river; the second is Sweetwater Creek, which empties into the Apalachicola
river a few miles north of Bristol, Florida. I have nymphal records ex
tending westwards from here as far west as Kushla, Alabama kbout ten miles
north of Mobile; these nymphs were collected from Seabury creek, a stream
which drains eastwards into the Mobile river* It would seem, then, that
for some unknown reason IS* apalaohioola stops just east of the Apalachicola
river, but westwards is not so closely confined* Even the change from one
physiographic province to another does not appear significant, for the
Georgia specimen was reoorded from the Piedmont, while all the others came
from the Coastal Plain* If my nymphs are merely aberrant forms of deficiens,


215
PARALEPTOPHLEBIA Laatage
Paraleptophlebia was described in 1917 to receive certain European
mayfly speoies whloh Lestage felt should not be retained in Leptophlebia*
His genus was not recognized by American students until 1934 when Traver
transferred to it all North American species which had formerly been
placed in Leptophlebia, except gracilis and johnsoni.
At the present time, the status of the genus Paraleptophlebia is
still in question, at least in so far as the North American species are
concerned* Ide (1935, 1937, and 1940) and Ide and Spieth (1939) have
disregarded Paraleptophlebla* Spieth (1938) apparently accepted this
genus bttt plaoed all species of Blasturus in Leptophlebia* This same
author (1940) in a paper on the North American species described by
Francis Walker used both of the names which he had formerly discarded*
There are certainly at least two distinot groups here, and, if taxonomio
confusion is to be avoided, these genera should be redefined. In the pa
pers by the two latter authors, neither discussed his reasons for his
generic choice.
When Traver recognized Paraleptophlebia for North American species,
she stated "examination of specimens, both nymphs and imagos of Leptophle
bia marginata Linn., shows that this speoies is quite distinct from those
North American species which have previously been described in the genus
Leptophlebia* All of these species, with the exception of .johnsoni MoD.,
which with gracilis Traver (in Blasturus) stand nearer to Leptophlebia
than to Paraleptophlebia. I am transferring to the genus Paraleptophlebia."
(1934s 189).
Paraleptophlebia includes thirty species in North America (north of


182
accumulated in a mass of Myriophyllum growing at the water's edge. The
Styx river is a fairly large, deep, almost stagnant body of water which
drains rather flat country and finally empties into the Perdido river near
the Gulf of Mexico. There were no Baetinae found although other stream
mayflies were present] however the conditions existant at the time of
collection would seem to preclude all except the most tolerant forms, and
this was found to be the case. The bed of the stream is soft, red clay
and the vegetation is confined to the shore zone, but even here it is
abundant only in scattered areas. V/here the nymph3 of Siphlopleoton were
collected, there was no preceptible flow and the plants, predominantly
submergent, formed dense mats.
A single specimen taken at Sandy creek was likewise found in vegetation
in the most slowly flowing part of the creek. This is a fairly large stream
with a rather noticeable current and very little vegetation. The plants
grow in protected plaoes where there is little movement of the water] the
situations in this creek which are favorable for the development of mayfly
nymphs are extremely scarce and this is reflected in the number of speci
mens of ephemerids from here. Broad, sandy stretohes dearly indicate the
origin of the name of the stream. The bed is loose, ooarse-grained sand
which constantly shifts with the current, allowing but little material to
become anchored.
Another specimen was taken from the Shoal riverwhich does not differ
essentially from Sandy creek a slowly flowing, deep stream with a shifting
sand bottom. The Siphlopleoton nymph was found dinging to vegetation
which grew around a piling driven deep into the sands to serve as a bridge
support.


44
Not only has the Apalachicola served as an entry for the ephemerid
fauna, but also the Suwannee and its tributaries may have brought in cer
tain elements fresa the north such as Braohyoerous. Very likely, in addi
tion, there lias been some migration along the more easterly Coastal Plain
region -where the streams descend from the higher Piedmont. However, the
forms which may have entered Florida over these or abhor routes are few in
comparison with those that have come in by way of the western path. Per
haps some species have entered by more than one route, moving in from the
east and from the west and meeting to form a unified population in northern
Florida.
Travers recent paper on the Ephemeropteran fauna of Puerto Rico and
infrequent records of other species from the West Indies show that those
speoies of mayflies found in Florida have but few affinities with the insular
fauna. No species are shared in common, and the genera which occur in both
regions are very widely distributed. Although other species of insects
have become established both in Florida and the West Indies, the mayflies
have been unable to do this principally because of the ecological conditions
of south Florida. The great majority of forms described from the islands
are inhabitants of streams, particularly of mountain streams, and even if
these mayflies were accidentally introduced into Florida, establishment
would be impossible in the south. If,by some rare ohanoe,a female which had
been fertilized were carried to one of the permanently flowing sand bottom
streams, it is barely possible that the speoies might gain a foothold, but
this has apparently not occurred* The only Florida speoies that might be
supposed to have been derived from the West Indian fauna are Callibaetis
floridanus and Caenis diminuta, but the former shows affinities with continen-


174
clay hills along the Apalachicola. Here the nymphs are confined to
those parts of the creeks where the flow is continuous although not neces
sarily rapid. Most frequently, the nymphs were collected from the roots
of terrestrial plants which projected into the water. Debris and silt
accumulates among the tangle of the roots and this trash, along with the
roots, furnishes an apparently ideal situation for the development of
the nymphs* Only rarely do the insects appear in collections made from
the cleanly washed roots in the swifter waters where Is onychia is so oom-
mon.
Although not as numerous as in the root situation, the nymphs also
live in leaf drift and among branches which become anchored rather per
manently in the stream bed. However, they seem to be marginal forms and
do not appear to be adapted to swifter waters.
The habitat of the Florida species is quite different from that of
Oreianthus purpureus. Traver (1931 103) found the nymphs of the latter
species only in swift water, at a depth of from one and one-half to two
feet, where they lived beneath large flat rocks. Her observations on the
same species in 1937 indicated that "The nymphs were usually found beneath
small, isolated boulders or irregularly-shaped sedimentary rocks in rapid
water* "
The spindly legs of the immatures and the presence of gill covers
indicates that the Florida nymphs find their natural habitat in the silty
places where they have been taken, rather than on the undersides of clean
ly swept rocks in midstream. Frequently large, submerged and well-anchor
ed logs were found in the stream bed, yt no Oreianthus nymphs were on
them. The other situations, then, must be more acceptable to the immatures


241
on previous dates
"Uoted a female flying alone near a spider web. After a few back
ward and forward movements, she became entangled in the web. This occurred
as she was backing up. Perhaps it is on the backward flight that the
adults are caught by the spiders."
Again on January 30, 1941, I was fortunate enough to observe mating
flights, but this tin two distinct types of behavior were exhibited,
"talked downstream about 250 yards and over this area saw twenty-one sep
arate mating flightsj every sunlit spot had its own. These varied in size
from two males to nearly one hundred. Observed two pairs in cop, but
only for a moment before they were lost in shadows* There seems to be
a definite correlation between size of swarm and height of flight. The
very small groups fly low 6 to 12 inches above the water; the large
swarms of twenty to one hundred males fly from 2 to 5 feet above the
water. Lode of flight in large swarms does not differ from that of small
except in height."
DERIVATION OF THIS OPEC IES: Since the species most closely related to
ii brunneipennis are northern or mountain forms, unknown from the Coastal
Plain, it seems evident that brunneipe nni s either itself originated in
the more mountainous or hilly regions of Georgia or Alabama, entering
Florida through the Apalachicola drainage, or that it has developed fn
tlie Coastal Plain from an ancestral stock of such origin. It might be
assumed that brunneipennis became isolated in the southeastern Coastal
Plain; as Florida rose after its last submergence, the species began to
follow the young streams into the new region*
LOCALITY RECOEDi Alachua Co* Devils Mill Hopper (April 18, 1933,
Alachua Co*


12
claw has become a comb-like structure and the major claw is no longer
distinct* For the most part, the sise of the tarsal claws is fairly uni
form within a genus, but this is not always so* In one genus, Centroptiluna,
there are two Florida species, one of which (vlridocularis) occupies slowly
flowing, the other (hobbsi) swiftly flowing water* In viridocularis the
claws are three-fourths as long as their respective tarsi, while in hobbsi
the claws are only one-half as long as their respective tarsi*
The nymphal leg structure, even in the non-borrowers, is correlated
with the habitat* Those species inhabiting ponds and relatively quiet
waters have rather elongated limbs which stand out from the body, holding
it above the objeot to which the nymph is attached* The sprawlers have
shorter,thicker legs, the femora being somewhat broadened; the legs are
held out horizontally from the body and do not serve to lift the insect
from the surface on which it is crawling* The dingers of swift water
have thickened, shortened legs with a correspondingly greater development
of the muscles. Their legs are held horizontally with the femora close
to the body; the latter are thin along the anterior edge but relatively
thicker posteriorly, thus presenting lessened resistance to the current*
The caudal filaments show special features in the freely swinaaing
and darting mayfly nymphs* In these species, there is a great develop
ment of hairs medially from the lateral filaments and laterally from the
median filament so that these hairs overlap to form a paddle. By rapidly
flicking the abdomen and holding the tails stiffly, a very efficient swimming
organ is formed and the insects oan move rapidly through the water* Those
species which swim little or not at all have a correspondingly small develop
ment of hairs on the caudal filaments, and in some of these nymphs the


298
Friauf, adults)* Hillsborough Co. Six-Mile Creek (March 26, 1938, L.
B., nymphs)| Hillsborough River (February 11, 1939, L* J. M., nymphs;
June 18, 1939, L, J. M*, adults). Jackson Co. Blue Springs Creek near
Marianna (June 9, 1938, L. B*, nymphs). Leon Co. 7 mi. S. Hwy, #19 on
Hwy. #127 (June 5, 1938, L. B., nymphs). Liberty Co. Sweetwater Creek,
Torreya State Park (June 10, 1938, L. B., nymphs; November 4, 1938, L. B.,
nymphs; July 1, 1939, L. B, nymphs). Madison Co* At Jefferson Co. line,
Auoilla River (June 4, 1938, L. B., nymphs and adults). Marion Co.
Silver Springs (May 7, 1934, R. R. Shepard, nymphs); Rainbow Springs Run
(March 9, 1940, L* B*, nymphs; February 26, 1939, L. J. M., nymphs);
Ocklawaha River at Hwy. # 38 (Maroh 19, 1938, L. B*, nymphs and adults).
Okaloosa Co. 5.1 miles W. of Walton Co. line (June 7, 1938, L. B., nymphs;
May 31, 1940, L. B., nymphs). Wakulla Co. ?/akulla Springs Run (May 29,
1940, L. B., nymphs and adults). Walton Co. 13.8 miles W. Freeport
(June 7, 1938, L. B., nymphs and adults); 9.6 miles W. of Portland (May
61, 1940, L. B., nymphs); 10.6 miles W. of Walton Co. line (May 31, 1940,
L. B., nymphs). Washington Co. Holmes Creek at Holmes Co. line (July
2, 1939, nymphs, L B.).




263
the shield* Once under the mesonotum, the oxygen-bearing water spreads
out over the other, greatly-branched, more anterior gills*
LIFE HISTORY When ready to transform, the nymphs crawl onto a project
ing surface until they are entirely clear of the water. In the laboratory,
I kept a rook partly in and partly out of the water, and this made an ad
mirable holdfast for young nymphs as well as a place for those preparing
to assume adulthood to crawl from the water* In the field, I have seen
only a single shed skin* This was found, with the claws firmly attached,
on a bridge piling in a sand-bottom stream* The exuviae were about two
or three inches above the surface of the water and was accompanied by nun-
erous stonefly skins* On the piling, as well as on the rock in the labora
tory, the nymphs assxmed a somewhat vertical position with the head up;
on the rock, they were on the upper side at its highest point* The nymphs
seem instinctively to crawl to the highest plaoe possible before emerging,
at least the evidence afforded by the peculiar behavior of the nymphs men
t oned above might indicate this*
To proceed from egg to adult takes approximately one year* This state
ment is based on preserved material rather than on rearing, as should be
be done for confirmation* The discussion of seasonal distribution includes
a disoussion of the sizes of nymphs at various times of the year* Growth is
greatest during the warn season as would naturally be expected* and those
nymphs hatched from eggs laid early in the emergence period are approximately
two-thirds grown by late fall* Of course, those hatched late in the sea
son receive their maximum growth the following spring and during the early
summer so that by late summer all of the eggs of the previous year are
accounted for in one way or another (there are many predators in the streams,


35
a time, vegetation and animals may become established, but frequently they
dry up in such a short period that such does not take place* The ponds
are shallow and may be large or small depending on the depression and the
drainage of the region*
(5) Jerome sinks Because of the unusualness of this situation, it deserves
special classification* A descriplton of the sink is included in the dis
cussion of the ecology of Choroterpes hubbelli on page V6 *
Lakes
According to the recent investigations of Mr* S. Stubbs of the Florida
State Geological survey, nearly all lakes in Florida are the result of
solution of underlying limestone} however* suoh lakes as Late Okeechobee
seem rather to occupy basins which are natural depressions in the surface
formed as the land rose during the last geologic period. "Many Florida
lake basins are simple sinks that have always been tributary to the ground-
water supply and never have had a surface outlet. Others at one time or
another formed part of the surface drainage and. therefore were connected
with the river system. Their history is complicated, for the fluctuations
of sea level and the consequent fall or rise of the water table gave
opportunity alternately to deepen the basin or to flood them. Some of them
appear to have been estuaries during higher stages of the sea, for the
sand-covered terraces around them stand within the limits of altitude of the
coastal terraoes*" (Coote, 1939: 100-101). Cooke concludes that Late
Okeechobee, Late Istokpoga* Late Xissiranee, Crescent Late, Late George,
and others originated as hollows in the sea bottom*
(1) Sand-bottom latea By far the commonest type of late found in Florida,


286
cussed elsewhere in this paper, is constructed very much lite hirsuta;
a somewhat flattened body, elongated legs and claws, operculate coverings
for the gills, hairy body, and occipital tubercles hirsuta, of course,
has only semi-operculate gill covers, otherwise its external characters
are similar to those of trilineata. It is quite probable that these charac
ters may be associated with moss-covered rocks, but in Perdido creek there
is only a sandy bottom with some dead wood but no rocks.
An examination of the literature shows that the only reference to
ecological habits of any species of the simplex group is made by McPunnough
(1331: 209) concerning E, simplex "The nymph occurred at Cascades Point
in very swift water, clinging to the underside of the limestone slabs and
being so covered with silt as to be almost unrecognizable: the smaller
Knowlton nymphs were in less rapid water."
Perdido creek is, for a Florida stream, rather rich in species of
mayflies. The associates in the stream, but perhaps not in minor habitat,
are centre 11a ephippiatus, Stenonema exiguum, S. smithae, S* proximrm,
Tricorythodes albilineatus, Baetisoa rogersi, Caenis hilaris, Baetis spino-
sus, Pseudocloeon blmaoulatus, Baetis spiethi, Xsonyohia pictipes, and
Isonychia sp.
SEASONS: The two nymphs in my collection were taken on April 5. One is
]ast instar, the other tertiultimate, indicating an emergence during April
and probably May. I would venture to predict that the species emerges
only during the summer, since,in this colder region of Florida and southern
Alabama,emergence of other mayflies appears to be predominantly spring and
summer, this being particularly true in the genus Ephemerelia.
LIFE HISTORY* Nymphal life probably lasts from nine months to one year*


o90
bottom streams where the vegetation is not extremely abundant but is scat
tered along the edge of the stream where the flow is evident and constant
The nymphs thrive among these plants, and along with other Baetinae form
the major faunal element* Hatchet creek, which has been described else
where, is a typical example of a stream in which spiethi prospers* In
this creek, the small beds of Potomogeton, Globifera umbrosa, mosses, etc*
make up the predominant vegetation from which the nymphs have been collected,
and here they may be found in the swiftest as well as the slowest part of
the flow* The nymphs are also abundant among the exposed roots of terrestrial
plants in the streams of the Torreya State Park region, which drain into
the Apalachicola river
In every stream from which spiethi nymphs were collected, spinosus
or australis nymphs were also collected or seen, but not all streams from
which spinosus was taken contained spiethi nymphs* The size of the stream
does not affect the presence or absenoe of nymphs for they have been collect
ed from brooks which were merely trickles as well as from streams as large
as the run of Wakulla Springs. This river, as well as other west Florida
streams from which collections were made, has dense growths of Vallisneria;
although the nymphs have not been found to be exceedingly numerous in the
eel grass, they do ocour there. Some of the streams near the western border
of the state have dense mats of Fotomogeton in which spiethi nymphs are as
common as they are in Hatchet creek*
The nymphs live on the undersides of the leaves, near their free ends,
where they are protected from the current and find food plentiful* Near
shore among the vegetation* they may be found most commonly on the stems
about halfway up from the stream bed* Occasionally nymphs are found in leaf


271
SEASONS E. trilineata Is a late winter, spring, and early summer species.
The period of principal emergence takes place during the spring in April,
but with scattered emergences from early February through late June. Traver
has recorded S. doris* emergence on March 21 and 22, May 6 and 30, and
July 4; the latter collection dates are from mountainous regions where
transformation would be expected to occur later than in the lowlands*
HABITSj E. trilineata nymphs blend perfectly with their backgound when
lifted from the water on sticks, boards, or other dark objects. It is only
when they begin moving about that they become obvious. Not that their
movements are rapid just the reverse they are very slow and deliber
ate, each step seems to be measured. As they move, i. e. out of water, the
tails may be flicked forwards over the abdomen and then straightened, only
to have the act repeated. The movement is very reminescent of that of the
Caeninae and of Qreianbhus. When placed in water, the nymphs again act as
do these two groups of mayflies by swimming awkwardly with undulatory move
ments of the abdomen, and then heading for some submerged object to which
they can clingj once attached, it is difficult to see them. The nymphs
are easily identified by their notions on the surface of a white enameled
pan characteristically they move forward slowly, not wriggling as do the
Leptophlebines, and occasionally flick the tails as described above. The
movement may be confused with that of the Caeninae, but the nymphs oan be
separated from this group by the easily seen saw-like margins of the abdo
men and the widely separated gill elytra.
I have been able to keep nymphs alive in the laboratory for as long
as two months, and during this period have fed them nothing but dead leaves.
Examination of the enfceron of wild nymphs indicates that they,too, eat the


442
Lestage, J. A* 1935. Contribution a letude des Ephemeropteresj IX
Le Groupe Siphlonuriden* Bull* Ann* Soo* Exit* Belg* 75s 77-139,
figs* 1-11.
Martynov, Y. 1922. The interpretation of the wing venation and trachea-
tion of the Qdonata and Agratha* Rev* Russe Snt* 18: 145-174, 3 text
figs, 1 pi. (Translation in Psyche 37s 245-281.)
Miall, L. C* 1895. The natural history of aquatic insects. London.
Mitchell, A* J. and Ensign* M. R* 1928. The Climate of Florida* Univ. of
Fla* Agrio* Exp* Sta. Bull* 200. Pp. 91-300, figs. 52-65.
Morgan, A. H* 1911. Mayflies of Fall CreekAnn. Enb* Soo* of Amer.
4 93-119, plates 6-12.
1912. Homologies in the wing-veins of mayflies. Ann. Exit.
Soo* of Amer. 5* 89-106. Text figs. 1-6, plates 5-9.
1913 A contribution to the biology of mayflies. Ann* 3nt.
Soc. of Amer* 6 371-413, text figs. 1-3, plates 42-54.
1929* The mating flight and the vestigial structures of the
stump-legged mayfly, Campsurus segnis Needham* Ann* Exit* Soo* of
Amer. 22: 61-68, plate I*
1932. The functions of the gills in burrowing mayflies
(Hexagenla recurvata). Physiological Zoology. 5i 230-245* 1 plate*
Morgan, A* H* and Wilder, J* F. 1936. The oxygen consumption of Eexagexiia
recurvata during the winter and early spring* Physiological Zoology*
9: 153-169, 3 text figs.
Morrison, E* R* 1919* The may-fly ovipositor, with notes on Leptophlebia
and Hagenulus. Caad* Exit* 51: 139-146. Plates 10-11.
Murphy, H* S* 1922. Notes on the biology of some of our North Araerioan
species of mayflies. Lloyd Library. Bull. 22, Exit* Ser* No* 2,
1-45, plates 1-7.
McLuimough, J. 1921. Two new
1 plate.
v'-yflies* Caad. Ent* 53: 117-120,
MoDunnough, J* 1923* New Canadian Ephemeridao with notes. Caad. Snt*
55: 39-50, text figs. 1-3*
1924b. New Canadian Ephemeridae with notes, II* Caad* Exit*
56: 90-98, 113-122, 128-133, plates 1-3.
1925a. New Ephemerelia species (Ephemeroptera)* Caad. Ent.
57: 41-43.


LSap 7. Distribution
Stenonama proximuau


156
sky rising and falling in their attempts to attract mates* The males
rose to a height of about forty feet above the stream and dropped to with
in twenty-five or thirty feet* The to-and-fro flight covered a distance
of approximately thirty feet, although the excitement m the swam that
was created by the sweeping of my net made this rather difficult to deter
mine* Even though I swept into the swam each time that it dropped to its
lowest level, the males did not disband, and finally the adults were
lost to sight because of the darkness* During the entire flight, not a
single female was seen to enter the swam, but after dark, many females
were attracted to my light and I saw large numbers of them rising from
the bushes close to the water* These females apparently had not yet, or
just recently, mated for they were still filled with eggs.
DERIVATION 0? THE SPECIES} JH* weewa, if it really is a distinct species,
is derived from a stock which gave rise also to H. orlando, H* mingo, H*
marilandioa, H* limnophila, and possibly others* The whole genus is such
a closely knit phylogenetic unit that it is difficult to say which species
are most nearly related*
Hexagenia weewa may be an endemic speoies bub it is unlikely that
it is restricted to only that portion of the Apalaohicola river that is
looated within the confines of Florida* It is more likely to have arisen
in the headwaters of the river and entered Florida in recent times. *
1* Spieth now eonsiders weewa to be H* munda elegans* H* elegans has been
recorded from the mountains of North Carolinaj the Etowah river at
Rome and Cartersville, Georgia; Jonesboro, Athens and Atlanta, Georgia
(Specimens from the last three localities were recorded as elegans by
Traver, 1935 (p. 265), but she suggested that they might represent a
new species).


386
the Santa Fe river, but most of them died en route. However, a few were
successfully transported to the laboratory, and several lived for slightly
longer than two days in an aerated aquarium. Of these, only females emerged.
Essentially, emergence is the same as in spinosus a few rapid dashes end
ing at the surfaoe, splitting of the thoracio covering, and almost immediate
appearance of the fully emerged subimago, which at once flies to the near
est support* Emergence lias also been observed oub-of-doors, and it was
found that the insects do not head for shore, but fly directly upward
until lost to sight. They probably seek the protecting leaves of the high
er trees.
The subimagos begin rising just about sundown and continue for approxi
mately thirty minutes, the peak being about fifteen minutes after emergence
starts. In the laboratory a subimago emerged an hour after dark, at 7i30
p* m., and underwent its imaginal molt at 807 a. m. This is an excessive
ly long subimaginal period, and, I believe, atypical, because most specimens
that were observed in the laboratory molted only eight to ten hours after
transformation.
The mating flight of B* intercalara has not been described, nor have
I ever observed it*
DERIVATION OF THE SPECIES? The species of the genus Baetis are primarily
northern* Baetis intercalara is no exception as indicated by the fact that
the nearest related species are found in the northern part of North America.
If the Florida fom is true intercalarla, it has probably entered the state
by way of the Apalaohicola and Mobile river drainages. The species, apparent
ly absent from the Appalachians, may have swung down from the north, skirting
the western limits of the mountains, perhaps crossing the Interior how


366
dinarily have nymphs, even though they may be there in ver/ limited numbers*
Many of these streams have so little vegetation and other suitable situa
tions for development of nymphs that only small numbers, compared to those
of the danta Fe river, can be supported. Only rarely do nymphs enter dense
mats of algae such as are formed by Spirogira and Batrachospermurn.
Physically, the waters inhabited by the nymphs of B* splnosus show a
wide range* The mroatures are found in streams ivith a very low pH (as
low as 5*0) as well as those which are definitely alkaline (as high as 7*8)*
In general, it seems that the nymphs thrive better in slightly alkaline
water with a pH about 7*3* The temperature factor is not particularly
important in Florida although it is of the greatest importance farther northj
however, during a cold spell the degree of emergence is greatly lessened
and may completely stop, but as soon as the waters begin to warm, the nymphs
again become active enough to attain the adult state*
Nymphs can tolerate standing water for a time, at least I have been
able to keep them alive in unaerated aquaria for as long as two days, and
in shallow pans of water for as long as three* If the water is aerated,
hbwever, the life of the inseot may be prolonged as much as two weeks in
the laboratory* This ability to tolerate standing water is probably one
of the factors which acoounts for the wide distribution of the species*
If the nymphs can live in intermittent streams and in those which flow most
of the time but which do occasionally become stagnant, it would greatly
increase the flexibility of the species* There is same field evidence which
indicates such tolerance* I have collected nymphs from several streams
which connect two bodies of standing water* Normally there is a slight move
ment of water from one of these bogs to the other, but during low water the


214
Co. .6 miles north of Live Oak road at Hwy. #41 (February 4, 1938,
L. B., nymphs). Jackson Co. -- 3.6 miles north of Altha (December 10,
1937, L. B., nymphsj December 1, 1939, L. B., nymphs). Jefferson Co.
Drifton (February 5, 1938, L. B., nymphs). Liberty Co. ~ Little Sweet
water Creek (December 10, 1937, L. B., nymphs)} Hosford (March 17, 1939,
L. B., nymphs). Okaloosa Co* -> Shoal River (December 11, 1937, L. B.,
nymphs); 2 miles east of Crestview (December 12, 1937, L. B., nymphs);
1 mile east of Crestview (December 12, 1937, L. B., nymphs). Walton Co.
2.1 miles west of Walton Co. line (May 31, 1940, H. H. H. and L. B.,
nymphs). Washington Co. Holmes Creek (December 11, 1937, L. B., nymphs).


112
quartult, tertlult, penult, and last instars of the species explaining
that the intermediate instars were not studied because of the difficulty-
encountered in estimating the instar from the material collected* The
morphological differences between interpunctatum. and canadense are very-
slight and development is essentially the same in both.
iieedham (1935* 90) gave the time of incubation of the eggs of S.
tripunotatum as eleven to twenty-three days. This is the only published
record of the actual time required for embryonic development of a species
of this genus.
The surest method of securing eggs from S* smithae which are reasonably
certain to hatch was found to be by capturing ovipositing females and
forcing them to continue oviposition in dishes which contained small amounts
of water. The eggs are liberated from the female in small masses as she
dips her abdomen and lightly touches the surface of the stream. After
liberation, the ova settle to the bottom where they absorb water which
causes a jelly-like substance to swell about each ovum, forming a trans
parent protective covering which is also adhesive. It may be of some sig
nifican that unfertilized eggs take anywhere from a few minutes to several
hours to form this jelly-like covering, but if the eggs are fertilized,
the covering forms within five minutes of deposition of the ova.
The eggs, either aerated or not aerated but kept in shallow dishes
of water, hatched in the laboratory over a period varying from eleven to
fifteen days. These figiires are net for two separate batches, but include
the earliest and latest hatchings observed in the eggs of three females.
Because of accidental mixing of the eggs when collected, I could not de
termine whether the earliest hatching eggs belonged to one female and the


153
in depth, and burrows were located without trouble from the bridge over
the stream. The nymphs build burrows which descend only a very short
distance so that a shallow scoop of the Needham apron net easily removed
the insects.
The nymphs were found burrowing in large numbers in the banks of
sand-bottom streams in Gadsden and Liberty counties. The beds of these
streams are mostly cleanly-swept,yellow sand, but deposits of reddish
clay mixed with silt are fonded at the edges and the nymphs burrow in this
material.
Stream size is probably not a limiting factor because nymphs were
taken from a small stream in the Tallahassee Hills region which was not
more than three feet across, and yet the immatures must be present in
prodigious numbers in the Apalachicola and Chipla rivers if the reports
of emergences which have reached me bear any semblance of truth.
I have been told that when the "willow flies" come out, they cover
everything, they form huge piles under lights, they make pests of them
selves, and finally, they make it "awful eaBy to oatoh bass." When the
adults are out in numbers along the Apalachicola, they cover the willow
trees which line the banks of the river and from this is derived the name
"willow fly." I have been told that the bass lie in wait under the willows,
and as the insects aooidently fall from their perch onto the water surface,
the fish immediately seize them. At this time all that one needs to do
in order to catch a "mess of bass" is to oast under the willows and the
bait is sure to be taken. The people of this region wait impatiently for
the arrival of the flies for their best fishing.
Professor Needhams description of these insects is well worth re-




100
STENONEMA Traver
In 1933 !raver reviewed the Ileptagenine mayflies of North America
and erected St e no nema to Include those species which were formerly placed
in Eodyonurus and same of which were formerly considered to be eptagenia.
After studying the type species of Ecdyonurus, she decided that this genus
did not occur in North America, but v/&8 confined to the ttCld 7orld.H
In general, adults, at least the males, are easily distinguished from
the other Heptageniidae, but as far as females are concerned, the diffi
culties involved in generic placement become much greater because there
is much overlapping of characters. Traver1s key to the genera of this family
ignores the females, and it is only by associating them with males that the
genus of this sex may be determined. The thread-like seventh gills of the
nymphs easily sets them apart from all other mayfly genera. Specific de
terminations in the genus Stenonema are sometimes rather doubtful, particular
ly in the interpunotatum group. Color differences and color patterns
are highly variable in same species and individuals collected from the same
place at different times may appear to be different species, although they
are, in reality, nothing more than variants of the original form. Keys
to the nymphs lead nowhere and serve only to separate the immatures in a
broad sense* hen more of the nymphal stages are known for the described
species of Stenonema, perhaps a more comprehensive and useful key can be
constructed.
Traver has divided Stenonema into two groups on the basis of geni
talia and, to same extent, by use of the wing venation. The nymphs of
the two groups, interpunotatum group and tripunotatum-pulchellum group,


417
Appalachians, the. ancestral species finally reached its southernmost
distribution in northwestern Florida, and here gave rise to C. nyasa
LOCALITY RECORDS: Jackson Co. 3.S miles north of Altha (December 1,
1830, L. B., nymph). Washington Co, Holmes creek (July 2, 1939, L. J#
M. and L. B., nymphs).


303
predators. Occasionally, they leave the bottom to climb a short distance
up the plant stems, but much more frequently they are found clinging to
the very bottom of these stems. Leaf debris and other trash accumulating
in shallow water also harbor Caenls nymphs, but these do not seem to be
as numerous as in the vegetation association. The margin of the vege
tation also appears to limit the nymphs, and even though there may be
debris beyond thlB shore zone, it is very rarely that the insects ven
ture into the deeper water#
Ponds and the edges of lakes covered with water hyacinths (Plaropus
crassipes) very seldom have Caenis nymphs, for there is usually no bottom
vogetation, and probably the oxygen oonterrt of the bottom waters is too
low to support even these rather tolerant nymphs. Likewise, sink-hole
ponds oovered with duckweed (Lenina minor) and Brunnerla punctata very
seldom possess populations of this species, since,in most of these waters,
attached vegetation is completely laoklng and there is much deoaying vege
tation. The combination of these factors may be sufficient to render the
bottom of these ponds unsuitable for habitation# An interesting oase exists
on the oampus of the University of Florida* There are two sink-hole ponds
approximately one-fourth of a mile apart on the grounds of the experiment
station. One of these ponds is completely covered with duckweed, the
other.is entirely free of the plant but has a luxuriant growth of Riooia
fluitans. In the latter pond there is a thriving population of £ dim
inuta nymphs, while the former is completely barren of this speoies.
Mayflies are not the only animals affected by the paucity of ¡oxygen in
duckweed-oovered pond, for here the usual pond associates of C# diminuta
are also either entirely absent or very rare.




190
northwestern portion of Florida. Because of the indefiniteness of characters
for separation of nymphs, it is uncertain whether the specimens from the
Suwannee and Santa Fe rivers are L. perdido or I. piotipes; it is likely,
however, that they are the nymphs of the latter species since one adult
male was collected from a bridge over the Suwannee river. Disregarding
these more easterly localities, _I. perdido is distributed from the eastern
tributaries of the Apalachicola river to the western boundaries of Florida.
A few specimens from Mobile county, Alabama, likewise seem to fall into
the same general group and are probably 1 perdido. Large areas in this
northern part of Florida are seen to lack these inseots, but their absenoe
is probably due to ecologioal causes, many of the streams of this region
being unsuitable for the nymphs. (Jee ^'
ECOLOGY i Isonyohla perdido nymphs aire found only in flowing water where
the ourrent is most rapid. The majority of streams which are inhabited
by this species are of the sand-bottom type. In almost no instances were
nymphs collected from th9 beds of Yallisneria, Potomogeton, etc. which
form such an important element of many of the streamsj however, they were
very frequently found on submerged logs, rocks, boards, etc. which were
solidly anchored in the stream. Collections from the few riffles encounter
ed in these west Florida creeks included no specimens of Isonychia. The
most productive situations in the Florida streams are masses of debris
caught in the swiftest parts of the current. This mass is usually made
up of branches, leaves, small sticks, etc. which have caught on some per
manently fixed obstruction in mid-stream. Here the nymphs generally cling
to the sticks and larger structures, and as soon as these objects are
disturbed, the immatures release their holdj thus they are easily collected


359
DERIVATION OF THE SPECIES} As mentioned above, the species may have
migrated into Florida along the Apalachicola river drainage system This
would necessarily intimate that propinquus is distributed over northern
Alabama and in that region lying between northern Illinois and Alabama#
The species may have migrated southwards to the west of the Appalachians
as far as northern Alabama, barely entered the mountains, then crossed
them and spread into the Chattahoochee river* Another possibility is that
the origin of propinquus occurred in the southern Appalachians and from
here migration ivas both north and souths however, this explanation does
not seam as reasonable as the former, for in propinquus appears to be
a recent entrant into the Coastal Plain*
LOCALITY RECORDS: Alachua Co. Santa Fe River (October 25, 1939, L. B,
adult). Hillsborough Co* Hillsborough river (October 21, 1940, L. J* M*,
adults). Jackson Co* Blue Springs cre9k near Marianna (July 1, 1939,
L. J, M* and L* B, adults)*


346
the species was reported to be ovoviviparous (Berner, in press). In Travers
presentation of Callibaetis (1935) the species ivas redescribed, but since
only the female was known and since she had no specimens of men this sex,
C. pretiosns still remains very poorly known. If the Florida species is
nrotiosus, then all stages in its life history are represented in my collec
tion.
In Callibaetis imagos, there is a very marked sexual dimorphism. The
female pretiosus, as usual for the genus, is strongly marked over the body
end has a brown vitta in the fore wing, also she has numerous cross veins
behind this vitta and double intercalarles along the outer margin of the
fore wing. The male has the normal darkened thorax and darkened distal
abdominal segments with the pale intermediate area, but in the fore wings,
behind there are relatively few cross veins no more than in the
male of C. florldanus and the marginal intercalarles are usually single.
Even though the females are very easily distinguished from one another,
the moles of the Florida species are so similar that they cam he differen
tiated only on the basis of coloration of the abdominal tergites. The
nymphs, on the other hand, are easily separated from those of florldanus, but
since so few Callibaetis nymphs have been described, it is impossible to
state whether the type of flap found on the seventh gill of pretiosus is
unique.
DISTRIBUTIONt The distribution of pretiosus in Florida parallels that of
£. f. minor. I have recorcs from as far south as Hillsborough county,
as far east as Volusia county, northwards into Echols county, Georgia, and
westwards into B&ldwin county, Alabama. As mentioned above, the only other
locality record i6 from Virginia, the type locality of the species (ce


370
the path of the giant dragonflies which begin to patrol the stream as the
sun sets* The slow flight and helplessness of the mayflies makes them an
easy and choice prey for these Odonata* One day during the spring, as I
stood in midstream netting subimagos which rose from the stream, a large
dragonfly darted in front of me, grasped a mayfly which was almost in the
net, and was away without even entering the moving bag* Another excellent
indicator of emergence is the increased activity of the insectivorous birds
along the stream margins*
Among the most important deoimators of Baetis spinoBus subimagos
and adults are the spiders which are so numerous along the streams. Many
adult mayflies have been found entangled in the meshes of spider webs under
bridges, and subimaginal skins have also been found in these webs* If
the subimago does not entangle itself too badly and if the spider does not
at onoe kill the insect, there is some chance of its becoming free at its
final moltj this is, however, a rare ooourrence*
If the subimago escapes predators, it alights and becomes motionless
and inconspicuous, and hardly moves during the entire period of its life
as an immature adult* After a period varying from seven to ten hours,
the final shedding occurs* The imago remains in a resting state until time
for the mating flight* At Ithaca, New York, Baetis performs the mating
flight in the forenoon) no observer has been fortunate enough to note
tills phenomenon in B* spinosus. While resting, adults of Baetis, both
male and female, frequently twitch the abdomen and swing the caudal fila
ments from side to side*
Emergence of the subimago of B* spinosus has frequently been observed
in the laboratory* When ready for this to occur, the nymph floats free


396
CENTROPTILUM Eaton
In 1869, Eaton established Centroptilum to accomodate those European
Baetinae in which the interoalaries of the fore wings are single and which
possess metathoracic wings In his revision of the mayflies, a species
from Cuba was included in the genus as well as a reference to a species
close to C. luteolum (European) from the Hudson Bay region Eaton again
wrote of Centroptilum in 1892 when he treated the Ephemerida of Central
America Although no work had been done on this group in North America
since his monograph, he stated "A comparatively small genus, widely dis
tributed in Europe and North America, and recorded from Cuba." To this,
he added an unknown Centroptilum from N Sonora, Mexico The status of
the genus in the western hemisphere remained thus until 1923 when Mc-
Dumough published descriptions of C fragile and £. curiosum Following
this publication, descriptions of new species of Centroptilum began to
appear frequently, and now there are twenty species known to occur north
of Mexico, fourteen of which were described by McDunnough
Previous to the work in Florida, the genus was entirely unknown from
either the Coastal Plain or Piedmont. Traver has recorded C. albm (?)
from the mountains of North Carolina and Centroptilum sp* from the moun
tains of Alabama These records bring the genus as close to Florida as
it was previously known to occur. Centroptilum occurs in the Holarotic
area, in Africa, and is generally distributed in the Nearctic; in this
latter region, however, it has never been taken west of Kansas.
Ide (1930: 222-224) very briefly mentioned the habitat preference of
C. conyexum and C. bellum; beyond this, nothing has been written about


94
(28)
27 (26)
27'
28 (26')
28'
A whorl of spines at each tail joining* maxillary palp absent
(see fig. 21).
(Serrata group) Bphemerella apalaohicoja
Tails fringed with long hairs in the apical portion, may have
whorls of spines at the base; maxillary palp normally develop
ed (see fig. 22).
(Keedhami group) Bphemerella ohootawhatohee
Gill rudiment present on segment 1; gill on segment 4 operoulate;
maxillary palp wanting; segment 9 longer than segment 8 (see
figs. 20 and 21).
(Bicolor group) Ephemerelia trllineata
Gills on segments 4-7 only; gill on segment 4 usually semi-
operoulate; segment 9 not longer than segment 8; maxillary
palp present.
(Simplex group) Bphemerella hirsuta
29 (24') Head with three prominent tubercles. Maxillary and labial palpi
two segmented (see fig. 23). Posterolateral spines on middle
abdominal segments upcurved.
Brachycerous (30)
29' Ro such tubercles on head. Maxillary and labial palpi three
segmented (see fig. 24). Posterolateral spines on middle ab
dominal segments not upcurved.
Caenis (31)
30 (29) Tuberoles present on the lateral margins of the pronotum.
Brachycerous infrequens


86
36
37 (33;
37
38 (27)
38
39 (30)
39'
? Hind wings with aoute costal angulation; .15-.28 ram. in
length. Posterior is&rgin of heart margined with red-brown.
Baetis spiethi
Fourth segment of forceps about as broad as long. Jesothoracio
wings five millimeters in length; two long intercalarles in
first interspace. Three longitudinal veins in metathoracio
wings.
Baetis irrboroalaris
fiendish markings present on abdominal tergites 2-6.
Acentrelia ephippiatua
No reddish markings on abdominal tergites 2-6.
Ace nt re11a prop inq tras
Marginal intoroalarios occur singly (see fig. 15).
Cloeon (39)
Marginal intorcalarieB paired.
seudocloeon (40)
abdominal tergites 2-6 of the male yellow!sh-white; small sub-
median red dots on tergites 2-6 near the posterior margin, like
wise above the spiracular line near center of each side.
Cloeon rubropictum
Characters of ad alt not known.
Cloeon nyssa
40 (38') Large ruddy patches on tergites 2-6.
(41)
40 Abdominal tergites 2-6 immaculate or with very limited markings.
(42)


April 1, 1939, L B.,adults; June 24, 1939, L. B,, adults); Santa Fe
river at Poe Springs (May 14, 1934, J. S, E,, nymphs; February 12, 1938,
L. B., nytaphs; March 12, 1938, L. B,, nymphs and adults; March 18, 1938,
L, B., nyiaphs and adults; February 18, 1938, L. 3., nymphs and adults;
October 3, 1939, L. B., nymphs and adults; April 6, 1940, L* B., nymphs
and adults); Santa Fe river at Hwy. -¡¡- 41 (May 14, 1938, L. 3*, nymphs);
Near Worthington Springs (February 5, 1939, A* C. Chable and W, Beck,
nymphs). Bay Co. 28 miles north of Panama City (June 8, 1938, H. H. H.
F. II. Y., and L. B,, nymphs); 28.7 miles north of Panama City (June 8,
1938, L. B., nymphs). Calhoun Co. Chipla river (November 5, 1938, L.
B., nymphs). Duval Co. 11 miles north of Jacksonville (August 28, 1938,
H. H, H. and L. B., nymphs). Gadsden Co. 15.1 miles east of Chattahoo
chee (April 1, 1938, H. H. II, and L. J. M., nymphs). Gilchrist Co.
Suwannee river at Oldtown (April 5, 1938, L. B., nymphs and ad tilt s;April
25, 1938, L. J. M., adult)* Hillsborough Co. 2 miles west of Alafia
(March 26, 1938, L. B., nymphs and adults); Hillsborough river State Park
(August IS and 18, 1938, T. II# Hubbell and J, J. Friauf, adults); Dug
creek (August 15, 1938, T. H. Hubcell and J* J, Friauf, adults); Hills
borough river (February 11, 1930, L. J* M*, nymphs and adults; February
25, 1939, L. J. M., adults; October 21, 1940, L. J. M, adults). Jaokson
Co* 3.6 miles north of Altha (June 9, 1938, H II. H., F. H. Y., L. B.,
nymphs and adults); 12.2 miles southeast of Marianna (June 8, 1938, H. H.
II., F. N. Y., L. B., nymphs); Blue Springs creek near Marianna (May 6,
1933, adult; December 11, 1937, L. B., nymphs; June 9, 1938, H. H. II.,
F. II. Y,, L. B., nymphs; July 1, 1939, L. J. M. and L. B., adult; June
5, 1940, H* H. II. and L. B., adults). Leon Co. 15.5 miles west of


207
more frequently encountered in the leaf drift along the creek margin than
in the pools, -while the reverse is true of the mature nymphs*
Connecting with Hatchet Cfeek, near Gainesville, there is a fairly
large, stagnant canal from which water disappears during the dry season.
The canal passes through a rich mesophytic hammock, and has its floor paved
v/ith leaves partially buried in silt. In February, 1938, several nymphs
in their last instar were collected here by a friend; I visited the same
canal in April and found no trace of Blasturus. Previous to their emergence
the mature nymphs must certainly have migrated into the canal, since no
mature nymphs were found here on other occasions; this migration probably
is not comparable to that studied by Heave since his nymphs migrated up
stream against swiftly flowing miter and were not all mature. I believe
that quiet water is essential for the emergence of B* intermedins and
that maturation of the gonads acts as a stimulus, forcing the nymphs to
find this ideal situation* The young nymphs,often found in small numbers
with the more abundant mature ones in quiet water, have probably wandered
there accidentally.
The adults are less tolerant of dessication than many mayflies, and
are confined to mesophytic conditions where the humidity is rather high*
If the subimagos are removed from this moist environment, the final molt
is almost impossible, or at least laboratory rearings seem to indicate
this.
The oxygen content of the almost stagnant water must certainly be
low (no determinations were made),but the large gill expanse with the many
tracheal branches provides much surface for gaseous exchange*
Most common associates of Blast urus nymphs in the leaf drif are other




242
nymphs; Ootober 25, 1937, F# N# Y#, nymphs; March 5, 1938, L# B#, nymphs
and adults, imagos reared March 11, 14, 19, 20, 22, 23); near Worthing
ton Springs (February 5, 1939, W. M# Beck and A C# Chable, nymphs); 2 l/2
miles west of Gainesville (January 16, 1938, F# N# Y* and L. B#, nymphs
and adults; January 29, 1938, L# B*, nymphs end adults; February 3, 1938,
L. B*, adults; February 6, 1938, L# B#, adults; March 5, 1938, L. B. and
J. M. Martin, nymphs and adults, adults reared March 12, 16, 19; June 18,
1938, L# B#, nymphs and adults, imagos reared June 20, 21, 22, 23, 24, 25,
26, 27, 28, 30, July 8, 10, 12; January 7, 1939, L# B#, nymphs and adults,
adults reared January 9, 11, 16, 25, 30; January 28, 1939, L. B., nymphs
and adults, imagos reared February 2, 7, 10; Maroh 10, 1939, L# B#,
nymphs and adults, imagos reared Maroh 12, 15, 16; November 11, 1939,
L. B#, adults; February 5, 1940, L# B#, nymphs and adults; March 18,
1940, L. B., adults; March 19, L# B#, adults; April 17, 1940, L# B.,
adults; January 30, 1941, L. B#, nymphs and adults); experiment station,
University of Florida (January 15, F# N* Y#, adults and nymphs)# Bay
Go# 5*6 miles north of Panama City (November 5, 1938, L# B#, nymphs;
May 30, 1940, H* H# H# and L# B#, nymphs)# Columbia Co# Falling Creek
(November 13, 1938, L# B#, nymphs) Hamilton Co* 8#3 miles south of
Jasper (February 4, 1938, L. B., nymphs)# Jackson Co# 2*9 miles north
of Altha (July 1, 1939, L. J# M# and L. B#, nymphs and adults); 3#6
miles north of Altha (June 9, 1938, L. B#, nymphs and adults)# Jefferson
Co# (April 1, 1938, H. H. H# and L. J. M#, nymphs); Drifton (February
5, 1938, L# B#, nymphs)# Leon Co# 11#2 miles west of Tallahassee
(Maroh 16, 1939, J# S# R# and L# B., nymphs and adults); 16*9 miles west
of Tallahassee (March 17, 1939, J. S# R# and L. B# nymphs); 7 miles


145
is from a lake in the Ocala National Forest.
HABITS: The burrowing habit is very strongly developed in the nymphs
and all bodily structure is adapted to suit the immetures to an hypogeio
existence. The gills present an enormous aerating surface, the lege
are modified for digging and casting out the soil as it is passed back,
and the incisors of the mandibles are elongated into tusks as accessory
digging organs and (according to Needham) for lifting the roof of the
burrow,
^jojgan and Grierson (1932) described very dearly the gill movements
and digging of Hexagonia recurveta. The actions appear identical with
those of H. limnophlla. I quote (p. 233): "Waves of motion pass baokward
over the gills sometimes too rapidly for the eye to follow but at other
times in listless ripples. The gills may cease moving altogether, us
ually for a few seconds or for 1 or 2 mintues, though at times they may
be quiet for half an hour. The motions vary with those of the nymphs
body and also with the temperature and chemical content of the water.
When resting, the gills are held almost upright or bent slightly back
ward. When waving, each pair bends backward, the filaments of the opposite
gills touch each other, instantly separating as the gills are pulled
upward, the whole performance resembling the rapid opening and closing of
a V. Bo far as observed, the gills move whenever the nymph is active,
especially when it burrows. While digging, the nymph holds its front legs
closely against its wedgeshaped head, then lunges forward, at the same
time pushing these legs outward. Almost synchronously with this, its
middle legs are pushed outward and baokward and the hind legs backward.
As its body wedges forward, the nymph fans the silt with its gills, opening


78
8 (l* )
8
9 (8)
9*
10 (9
dark* Abdomen of female yellowish-white; prominently marked with
purplish-brown Inhabits streams.
Kexagenia orlando
Hind tarsi with five freely movable segments. Venation not greatly
reduced; cubital intercalarles in two parallel pairs, long and
short alternately. Eyes of male simple, (see fig# 2).
Reptageniidae (ileptageninae ) Stenonema (9)
liind tarsi with three or four freely movable segments. Cubital
intercalarles not as above. Venation sometimes greatly reduoed
(see fig. 8)# Eyes of male often divided.
Baetidae (11)
Brown bar in fore wing uniting 2-4 cross veins in space between
R-^ and Brown spot at tip of fore wing just below Rg (see fig.
9). Penes with spine6 along lateral border (see fig. 10). Body
of male yellow; of female yellow, but if eggs present, abdomen is
brilliant orange.
Stenonema proxiaum
Wing without brown bar. No brown spot at tip of fore wing (see fig.
2). Penes without spines on lateral borders (see fig. 11). Both
sexes white.
(10)
) Bark spiracular spots present on abdomen. Tails narrowly annulate
with purplish brown at joints. Posteromedial portion of penes an-
gulate (see fig. 11).
Stenonema smithae
10
Bark spiracular spots absent. Tails not banded. Posteromedial


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547
ECOLOGY: Callibaetis pretiosus b much the same as C* floridanns miner
ecologically, and frequently the two species can be found side by side in
the same roadside ditches, ponds, or lakes. However, there are no indica
tions that the nymphs inhabit brackish water, and the range of acidity-
alkalinity seems to be somewhat narrower than for the former species.
SEASONS: The species emerges throughout the year in Florida; however, in
its more northern environs, the season of emergence is doubtlessly much
shortened.
LIFE HISTORY: The life history of pretiosus is very much the same as that
of floridanus.
CERIYATIGIT OF THE SPECIES: If the Florida specimens are not pretiosus,
they are certainly derived from the same stock,and probably migrated from
the north into Florida by way of the ponds, ditches, and other standing
viators of the Coastal Plain. Origin in Florida appears to be unlikely, for
no other species which resemble pretiosus in wing characters are known
to occur in the southeast*
LOCALITY RECORLSs Alachua Co. , Gainesville (March 22, 1937, L. 3, nymphs
and adults; May 11, 1937, L. B., adults; November 4, 1937, H. K. Wallace,
adult; January 23, 1938, J. R. Freer, adult; August 17, 1938, J. R. Freer,
adult; August 20, 1938, L. B., nymphs and adults; November 21, 1938, L. B,
adults; March 29, 1939, A. IT* Tissot, adults; April 13, 1939, L* 3., adults;
June 30, 1939, L. J* M., adults; September 3, 1939, L. B, adults; Octo
ber 5, 1939, L. B., nymphs end adults; October 6, 1939, L. 3., adults;
March 13, 1940, L. 3., adults; March 30, 1940, L. 3., adults; April 19,
1940, L. B., adults); Swamp back of Lake Newnan (January 15, 1938, nymphs
and adults); Hatchet Creek (April 2, 1938, L. B.,
adults; February 16,


377
australis* other relative* spinosus whose distribution has been discussed
elsewhere in this paper, inhabits identical situations tilth it*
An interesting note is introduced when the distribution of spinosus
is compared tilth that of australis* The latter species is confined to the
Coastal Plain, but the former,apparently with no better adaptations, is
known to occur from Canada to Florida* It would seem from this that both
australis and frorndalis are derived from spinosus or something very close
to this latter species, australis arising at one end of the range, frondalls
at the other* The only fundamental difference in this group of species seems
to be in the presence of the enlarged projections on the medial surface of
the claspers of spinosus; the dark color of the abdomen may be linked with
a reduction in size of the projections in frondalis and australis* (See /n^/7)
ECOLOGY Identifiable nymphs end adults have been collected only from
acid streams* All of these creeks fall into the sand-bottom and silt-bottom
categories. In the former streams, the nymphs can be found living on the
vegetation in the most swiftly flowing portion as well as in the slowest
areas* Just as spinosus, the nymphs tend to remain near the distal parts
of the plants where the flow is greatest and where the deposit of silt is
least* Debris of all sorts may have nymphs on it, particularly submerged
logs,where the nymphs hide in the cracks and crevices on the downstream
side* In the Alachua county creeks, the nymphs were found principally on
June us repans, and on a moss which grows profusely in certain parts of same
of the streams where the flow is at least noticeable* The west Florida
nymphs were chiefly inhabitants of the dense mats of Vallisneria and Poto-
mogeton which choke the streams*
The silt-bottom streams from which nymphs were taken have luxuriant


4
B2
angulation; two terminal segmenta of foroeps short, together
not one-fourth the length of proceeding segment; reflexed
spur subolavate at tip. (See figs. 19, 26, 27)*
llabrophlebiodes brumeipennis
21* Suboosta of hind wing extends almost to ape-: of wing* Two end
secants of forceps together equal in length to the proceeding
segnent* Koflexcd spurs long and slender, not subolavate at
tip. (bee fig. 20).
22 (19*)
22
23 (22)
23
Habropiilebia vibrans
0
Liiddle tail shorter and weaker than laterals.
Blasturus intermedius
middle tail approximately equal to laterals in length and thick
ness. Penes partially united (see fig. 29).
Paraleptophlebia (23)
ieflexed spur of penes ourved, spatulate, reaching to bottom
of cleft between penes; penes united for one-fourth their length,
long and tapering (see fig* 20). middle abdominal segnents of
male brovm* Blackish rings on apical third of all femora. Wings
with a brownish tinge; stigmatic cross veins anastomosed.
faraleptophlebia bradleyi
heflexed spur of penes claw-shaped; penes united for one-half
their length (see fig* 29)* Middle abdominal segments of male
predominantly white. Femora without dark rings* Wings odorless;
stignatic cross veins but little anastomosed* (bee fig* 30).
Paraleptophlebia volitans
24 (16)
Cul of fore wing consist of series of forking or sinuate vein-


512
the body fresa side to side, the other legs finally were pulled loose;
vfith these, the nymph then seized the bottom trash, and clinging, even though
his legs had not yet sti-ax^oened, pulled the remainder of his body from
the egg. The tails, however, adhered to the egg membranes so that I had
finally to detach the animal. The entire procese took about two minutes#
Many nymphs when first hatched have the antennae and tail3 crinkled, the
legs bowed, and the abdomen twisted to one side, but this condition soon
corrects itself and within a few hours these nymphs are quite normal.
At times the condition persists for several days, probably until the first
molt."
The eggs of C diminuta are among the most interesting produced among
the mayflies. The surface of the ovum has been described by Smith (in
Needham, Traver, Hsu, 1935s 82) but very little else concerning the eggs
is mentioned. The eggs are released by the female in a somewhat spheri
cal mass and as she touches the water, this mass immediately breaks up
into the individual eggs whioh scatter and sink. As they fall, a tangle
of thread-like, sticky fibers is released and these fibers cling to the
first solid object with which they oome in contact. Once an egg is attach
ed, it is rather difficult to tear it loose without injuring the filaments;
if the egg is freed the remaining threads may beoome reentangled. There
is no swelling of the chorion or formation of a protective jelly-like
coat as in many other species of mayflies.
Upon hatching, the young nymphs begin to search for concealment and
food. The young insects are rather transparent and almost ary background
is sufficient for concealment, except that in many cases the spreading
caudal filaments are very evident. Swimming aotions are very awkward;


406
C. viridocularia on the basis of gill structure and by the fact that the
venter of 0. liobbsi is unmarked*
DISTRIBUTION: Distribution records are few and scattered. The species is
known from Hillsborough, Alachua, fiar ion, and Jackson counties. C. hobbsi
is less widely distributed than C. viridocularis and its limiting factors
are ecological. The species is entirely unknown outside of Florida.
See enAfi /V
ECOLOGY: The factors limiting C. hobbsi ecologically are rather complex,
but two are obvious. First, the species is entirely confined to streams?
and,secondly, tuese streams must be definitely basic in reaction. In re
gal'd to tiie latter character, nymphs have been taken most commonly from the
uanta Fe river at Foe ¡springs in which the pH is 7.3, but other streams
in which the nymphs were found nave ranged to and above 8.0. For the most
part, the rivers and creeks in which C* hobbsi nymphs occur are spring fed,
and, in some cases, they are even spring runs.
The spring runs have been described previously and the Santa Fe river
has also been treated. Both situations, it will be recalled, have abundant
growths of Vallisneria and other water plants in mid-stream. C. hobbsi
is definitely an inhabitant of this vegetation zone in streams, and has
rarely been taken from other regions. The nymphs are dingers, attaching
themselves by means of the claws to the long, trailing strands in moderately
swift to swiftly flowing water. The immatures occur in as swift water as
the Vallisneria can tolerate, and they can also be found in the more slowly
flowing portions where Nais and ether aquatic vegetation become predominant.
The claws of this species are much shorter and stouter proportionately than
are the claws of C. viridocularis? this condition is correlated with the
faot that C. hobbsi inhabits so much more rapidly flowing water.


352
of the two species are almost identical In well-marked nymphs* the pro
minent red-brown tergites of segments two, five, and eight and the reddish
markings on the venter easily separate A. ephipplatus nymphs From A
proplnquus ephipplatus adults may be separated by the ooloration of the
middle abdominal tergites of the male of the latter speciesj the female
and nymphs of the former are not known from Florida
DISTRIBUTIONS A ephipplatus is widely distributed in northwestern Florida
and in the two southern counties of Alabama! in the remainder of Florida,
however, the species is poorly known A. ephipplatus was described from
Fort Valley and Rome, Georgia, localities in two completely distinct phy
siographic provinces Rome is looated near the southern tip of the Valley
and Ridge province, Fort Valley is on a plateau just below the Fall Line
Hills The Florida and Alabama records are, of oourse, from typical Coastal
Plain country* (See /%)
ECOLOGY* Nymphs inhabit sand-bottom streams where they ding to the vege
tation* I have found them most commonly in those creeks emptying into the
Choctawhatohee Bay, which have dense growths of Vallisneria, Potomogeton,
Sagittarla, and algae in all parts except the deepest. Although they have
a rather large mayfly fauna, from the standpoint of Florida streams A ep
hipplatus is one of the commonest ephemerids encountered in them* The
nymphs cling to the vegetation in the swiftest, as well as the slowest, parts
of the creek, but are seldom found on boards or in the very slow flow near
shore. Many of the creeks in the panhandle region of Florida are small,
shallow, and have very little submergent vegetation, but nymphs manage to
live in them clinging to the small bits of plant material and to the accumulat
ed debris. In these streams there is a paucity of habitats and this is


9
since large areas had to be examined in a relatively short time, but few
physical data were secured* This is naturally regrettable but unavoidable.
THE ORDER EPHEMEROPTERA.
The order Ephemeroptera is a natural grouping of primitive,pterygote
insects. In general, the fore wings are delicate, membranous, and triangu
lar in outline, and usually have intercalary veins and many cross veins; the
hind wings are much smaller than the fore wings and may sometimes be wanting.
The wings are normally held vertically over the back when the insects are
at rest* The mouth parts of the adult are vestigial and the alimentary-
tract lias undergone modifications fitting it as an aerostatic organ. There
are ten abdominal segments, and from the posterior end of the abdomen
either two or three caudal filaments arise. The inrush urea are aquatic and
undergo a hemimetabolous development. The mouth parts of the nymphs are
well developed for chewing; they possess two or three caudal filaments;
and gills are present on certain of the abdominal segments, iayflies
aro the only inseots which molt after they have attained functional wings;
prior to this final molt they are spoken of as subimagos.
The imago, or final adult form, can in most instances be easily differ
entiated from the subimago by several characteristics. The wings of the
subimago are dull and grayish, while those of the adult are normally
glistening and irridesceut; the hind margin of the wings of the sub imago
are ciliated while those of the adult (except in the daeninae and Triocry-
t Ixodes) are bare; the body of the sub imago is dull while that of the adult
is glossy; the fore legs of the subixaago are relatively short while they
become much elongated in the imago, particularly the male; the caudal fila-


264
but Baetisoa nymphs might not form such a pleasant element of the diet)*
Emergence data for only two specimens are at hand. A male emerged on
March 29 about 3:00 p* m., after remaining in the aquarium as a nymph from
March 17j the imaginal molt occurred March 30 between 9s30 and 10:00 a. m.
The second speoimen, a female, emerged at 2:45 p* m. March 31 and under
went its final molt April 1 at 8:45 p. m. The male took approximately
18 l/2 hours, the female 18 hours* A female subimago taken at light on
June 3, 1940 had molted by the following morning* Traver (1931a: 50)
found that the subimagnl stage of 3* Carolina lasted from twenty-one to
fifty-two hours; she attributed the great discrepancies in this period to
temperature, for during a cold period, a female remained in the submature
stage for at least fifty hours* During 1930, there wus a period of extreme
heat and the period was shortened to as little as twenty-one hours. Dr*
Traver has likewise found that B* thompsonae emerged and transformed in the
forenoon; here, we have other characteristics which might be of significance
in linking Q* rogersi closely with the two other species of its group.
I was unable to secure any data on longevity for B* gogersi, and there are
none available for other species of Baetisoa.
DERIVATION OF THE SPECIES: Baetisoa is primarily a swift-water mayfly
and has only recently entered the southeastern Coastal Plain as the sand-
bottom streams suitable for its needs became available. There appears to
be little reason for assuming that B* rogersi arose in Florida,for the
conditions necessary for the developaent of the species are rather recent.
B* rogersi is probably derived from a more northern species, one of the
Appalachian forms. It is likely that the species migrated southwards along
the Chatahooch.ee river drainage into Florida, where it lias spread westwards


281
LIFE HISTORY Refer to seasonal data
DERIVATION OF THE SPECIES: The same explanations of derivation given for
E trilineata may also be applied to £* apalachioola Of course, the parent
stook was different, but the factors influencing the movement into Florida
were very likely the same
LOCALITY RECORDS Bay Co 27*4 miles north of St* Andrews (May 30, 1940,
H K H* and L B, nymphs) Escambia Co Bayou Marquis (June 1, 1940,
H H* H and L. B, nymphs). Jackson Co 122 miles southeast of Mari
anna (June 9, 1938, H II* H, F. R Y, L. B, nymphs) Liberty Co. ~
Sweetwater creek (July 1, 1939, L J M and L, B., nymphs) Okaloosa Co* -
51 miles west of Walton county line (June 7, 1938, H H H, F N Y.,
L, B, nymphs; May 31, 1940, II* H H and L* B, nymphs) Walton Co
7.3 miles west of Ebro (June 7, 1938, H. E* H, F N Y, L. B, nymphs)
Ephemerella ohoctawhatohee ms name
TAXONOMY This rather rare species is represented in my collection by
only nine nymphs. These differ from all described Ephemerella nymphs, but
clearly fall into the needhami group as defined by Traver They are small,
five to six millimeters in length, the tibiae have a pale band at the apex,
the tarsi are banded with brown in the proximal third, the lateral exten
sions of the abdomen are moderately developed, and small dorsal abdominal
spines are present
The needhami group is probably one of the more primitive groups of
the genus, as indicated by the presence of gills on segments three through
seven, the presence of a maxillary palp, and, in some species, absence of
spinning.


224
7, 1938, L. 3*, adults); 7.3 miles west of Ebro (June 7, 1938, L. B.,
nymphs); 6*7 miles west of Portland (May 31, 1940, L. B., nymphs);
9.5 miles west of Portland (May 31, 1940, L* B., adults)#
Paraleptophlebia bradleyi (Needham)
TfXONOMYi Described by Needham in 1932, eighteen years after the specimens
were collected in the Okeefinokee swamp by J* 0* Bradley, Paraleptophlebia
bradleyi is unique, especially in the nymphal stage, which is here made
known for the first time* The female has not yet been found* The male
imago oan be separated from other species by its genitalia, laok of pale
abdominal segments, and tinted wings* Because of its distinctiveness,
it is rather difficult to say in whioh direction its affinities lie* For
the most part this is also true of the other speoies of Paraleptophlebia,
since the genitalia, usually one of the best indicators of relationship,
differ so greatly among the species of the genus.
The nymphs of P. bradleyi can not easily be confused with those of
any other species; in fact, they are so distinctive that Dr* Ide was
dubious as to the generic placement; this doubt was resolved by rearing
adults. The uniqueness of the nymphs lies in the structure of the gills,
which is more like that of Blasturus or Leptophlebia than that of Para
leptophlebia If, as Ide (1935* 124) and Spieth (1938) seem to think,
the species of Blasturus should be placed, along with Paraleptophlebia,
in the genus Leptophlebia, then bradleyi would be the connecting link
between Blasturus and Leptophlebia. This statement is based on a study
of the structure of the gills; in JP* bradleyi each gill is composed of
two distinct plates much as in BlasturuB, each lamella having distinct




Tallahassee (June 5, 1938, H. H. H,, F. N. Y*, L. B., nymphs and adults)?
7 miles south of Kwy. $19 on 127 (June 5, 1938, H. H. H*, F. N Y., L B,,
nymphs); 13 miles west of Tallahassee (November 30, 1939, L. B, nymphs).
Levy Co. Gulf Hammock (December 21, 1938, W* A. Mo Lane, nymphs). Liberty
Co. 4.5 miles north of turnoff to Torreya State Park (June 10, 1938, L.
B., nymphs). Madison Co. Aucilla river (June 4, 1938, L. B, nymphs);
4.3 miles from Jefferson county line (February 5, 1938, L. B., nymphs).
Marion Co. Rainbow Springs (February 23, 1939, L. J. M.,nymphs; April
15, 1939, L. J. M., adult; March 9, 1940, L. B.,nymphs, adults reared
March 13, 18-20, 26, 30, April 7); Ocala National Forest (July 23, 1938,
T. H. Hubbell and J. J, Friauf, adults); Qklawaha river at Eureka (Feb
ruary 12, 1938, L. B., nymphs and adults); Y/ithlacooehee river (March
25, 1938, L. B., nymphs); Silver Springs run (December 22, 1937, J. R.
Preer, adults), Nassau Co. 19.1 miles north of Duval county line
(August 28, 1938, H. H. H., nymphs). Okaloosa Co. 5 miles west of county
line (June 7, 1938, II. H. E., F. II. Y., L. B., nymphs); Niceville (June
7, 1938, H. H. H., F, II. Y., L. B., nymphs), Putnam Co. Red-water
Lake (March 26, 1939, C. J. Goin and L. 3., nymphs and adults). Santa
Rosa Co. 2 miles west of Milton (April 4, 1938, H. H. H* and L. J. M.,
nymphs and adults); 7.1 miles west of Milton (April 4, 1938, H* H, H. and
L. J. M., nymphs); Pace (June 1, 1940, H. H. H, and L. B., adults),
Wakulla Co. Smith Creek (June 5, 1938, L. B., nymphs); Wakulla Springs
run (May 29, 1940, H. H. H. and L. B., adults). Walton Co. 5.4 miles
west of Washington county line (May 31, 1940, H. H. H. and L. 3, nymphs);
10.6 miles west of Washington county (May 31, 1940, H. H. H, and L. B.,
nymphs); 15.8 miles west of Ebro (June 7, 1938, L. B,, nymphs and adults);


85
Centroptilura viridocularis
32
o extensive reddish areas on abdominal termites 2-6
Centroptilum hobbsi
33 (31*) Costal angulation present on hind wings (see fig. 35).
Baetis (34)
33' Ho costal angulation on hind wings (see fig. 36).
/¡.centre 11a (37)
34 (33) Second segment of forceps with prominent projection on inner
34
margin; excavation and spine between bases of forceps (see fig*
37). 9 Hind wings with very slight costal angulation* .42-.65
mm* in length* large U-shaped brown figure on head.
* Baetis spinosus
Second segment of forceps v/ithout prominent projection on inner
margin.
(35)
35(34) Middle abdominal segments of male dark. Small spine in exoava-
tion betxveen forceps base. Costal angulation of hind wing
much reduced (see fig* 13).
35
Baetis australis
Middle abdominal segments of male hyaline white. Costal angu
lation more prominent (see. fig. 35).
. (36)
36(35*) 3 Fourth segment of forceps twice as long as wide, (see fig.
38). Fore wings about 3 millimeters or slightly larger; short
marginal veinlets present in first interspace* Two longitudinal
veins in metathoracic wings.


304
Roadside ditches are one of the moBt fruitful places for collecting
C* diaiuta because*in these ditohes, predators are few (comparatively
speaking), subnergent vegetation is plentiful, and there is an abundance
of oxygen and food material* Cypress sv>jamps and marshes in which there
is vegetation or leaf debris also maintain populations of nymphs*
Sven streams may be inhabited by the nymphs of this species* In
these waters, they live in shallow regions among the rooted aquatic plants,
tiie roots of terrestrial plants projecting into the water, on submerged
logs, sticks, or other trash, and even on rocks in moderately swift water*
Of course, lidien in the flowing portions of the stream, they must cling
more olosely, and this limits their ability to move about* In standing
or slowly flowing water they move more freely*
The limits of toleration of the nymphs are surprisingly wide; they
are not only' tolerant to marked variations in acidity and alkalinity but
also in temperature and the amount of decomposition taking place in the water*
For this speoies the lowest pH recorded was somewhat less than 4*0 (the
apparatus would record no lower), the highest well above 8*0* The nymphs
must also be able to withstand great temperature variations beoause they
thrive in shallow pools continually exposed to South Florida sunlight,
and yet C* diminuta apparently gets along very nicely in the frosen waters
of Cajeada* Nymphs in all stages of development have been collected from
stagnating water from which arose most disgusting odores it may have
been that the decomposition had just recently begun, but,even so, it shows
remarkable powers of resistance on the part of the immatures*
Associated in the ponds and ditches with C* diminuta are only two
other speoies of mayflies, Callibaetis pretiosus ? and C. floridanus*


96
Seventh gill without a recurved flap (see fig 28)
34 (33*)
34
35 (32')
35
(34)
Found in southern Florida as far north as Highlands county
Callibaetis floridanus florldanus
Found throughout Florida north of Highlands county.
Callibaetis floridanus minor
Tails two, middle one represented by a minute rudiment (see
fig 29) Metathoracic wing pads absent*
fseudooloeon (36)
Tails three (see fig* 10) Metathoracic wing pads present or
absent
(39)
36 (35)
36
37 (36)
Tails with a brown band at the middle
(37)
Tails otherwise (see fig* 29)
(38)
Gills 1-6 unioolorous, tinged with brownj gill seven with lateral
two-thirds red-brown, inner margin clear (see fig* 30) Band
on tails dark brown.
Fseudooloeon bimaoulatus
37' All gills unicolorous, tinged with brown Band on tails light
brown.
Pseudocloeon punctiventris
38 (37') Length of median caudal filament less them width of laterals at
basej lateral filaments prominently banded with alternate dark
and light annulations (see fig 29). Grayish area in gills


139
The genus is generally distributed over North America but is poorly
known on the Pacific Coast¡ only a single species has been recorded from
that region (Dpholt, 1937). Hexagenia is also Neotropical and African,
but it8 greatest development seems to be in the Nearotio*
Four species of Hexagenia are known to ooour in Florida, and their
combined ranges cover much of the state. None of them is present in
the Everglades, because of the absence there of suitable streams or sand-
bottomed lakes*
An interesting note is introduced when geographio distribution and
the taxonomy of the group aire considered together* It is likely that
many of the present Hexagenia species are merely individual variants,
and this appears even more likely when we see that H* parolina, H* elegans,
H* marllandioa, H* mingo, H. orlando, and H* weewa, all very close relatives,
are recorded by Traver from the Apalachicola river drainage system (whioh
inoludes the Apalachicola, Chattahoochee, and Flint rivers and their tri
butaries )j _H* atrooaudata and II* bilineata, whioh are more distinctive
species, also ooour in this drainage. There are slight genitalio differ
ences among some of these species, but separation is principally based on
the use of color pattern* The difficulties encountered in classifying
specimens of this genus would seem to indicate that there has been too
muoh splitting, and that these color patterns may only be superficial
manifestations of definite phases in the life history of the population
considered as a whole* However, this problem needs much more attention
before it oan be satisfactorily solved.
Hexagenia and Ephemera are almost certainly dose relatives, and
were probably only reoently separated from each other. Spieth (1933* 350)


441
Hub bell, T. H* 1936* a monographic revision of tne genus Ceuthophilus*
Univ. of Fla. Public. Biol# Sci. Ser# Vol. 2, No. 1. Pp. 1-551,
plates 1-38*
Ido* Fa Pa 1930. Contributions to the biology of Ontario mayflies with
descriptions of new species. Canada Snt* 62: 204-213, plate 17.
1935.a.The effeot of temperature on the distribution of the
mayfly fauna of a stream* univ. of Toronto Studies, Biol. Ser. 39,
Pub. Ont. Fish. Res. Lab. 50 9-76, plates 1-10.
1935b. Post embiryological development of Ephemeroptera (may
flies). External characters only* Cenad. J* Res. 12: 433-478,
plates l-13o
1935c. Life history notes on Ephoron, Potaraanthus, Lepto-
phlebia, and Blasturus Tilth descriptions (Ephemeroptera). Caad.
Ent. 6? 113-1&5, plates 4-5.
1937. Descriptions of eastern North American species of
Baetino mayflies with particular reference to the nymphal stages.
Caad. Exit. 69 : 219-231, 235, 243, pis. 8-12.
1940. Quantitative determination of the insect fauna of
rapid water. Univ. of Toronto Studies, Biol. Ser. Pub. Ont. Fish.
Res. Lab., 59, pub. no. 47. Pp. 1-20, plates 1-4.
Imms, A. D. 1931. Recent advanoes in entomology. P. Blakistons Son
and Co., Ino. Philadelphia.
Krecker, F. H. 1915. Phenomena of orientation exhibited by Ephemerldae.
Biol. Bull., Marine Biol. Lab. 29: 381-388, 2 text figs.
LaForge, L, Cooke, W*, Keith* A., Campbell, M. R. 1925. Physical geography
of Georgia. Geol. Survey of Georgia. Bull. 42, pp. 1-189, plates
1-43.
Lestage, J. A. 1920. Nouvelles observations sur la ponte de Cloeon dipterum L.
Bull. Soc. Exit. Brussels. 2: 74.
....... 1924b. Contribution a l'etude des larves Ephemeres: Ephemer-
elliden. Ann. Biol. Lacustre* 13: 227-302.
1924o. Notes sur les Ephemeres de la Monographical Revision
de Eaton* Aim. de la Soc. Ent. de Belgique. 64:33-60*
1924d. A propos du genre. Caenis Steph. a Brachyoercus Curt.
Ann. de la Soo. Ent. de Belgique. $4:' "61-62.
1931d. Note a propos de 1*homonymie de deux Ephemeropteres.
Ann. de la Soc. Ent. de Belgique. 71:119.


291
ecologic factors of flowing water and by the acidity of the water Al
though numerous streams in southern Alabama were sampled, nymphs were not
found, but it does not seem probable that the genus is absent from the
region between Florida and Texas, where Tricorythodes is known to occur.
Very few localities in Georgia have been examined, and no specimens of
Tricorythodes have been taken from these, but I believe that T* albilineata
is more generally distributed throughout the Coastal Plain than my collec
tions would indicate. (See m*/3 /'<
ECOLOGY* Eoologically, the nymphs are confined to streams with at least
a perceptible current* They are moss and silt dwellers, occurring
occasionally on vegetation in the more swiftly flowing water As an ex
ample of an ideal situation where the nymphs are very plentiful, the Santa
Fe River cannot be excelled in Florida* Here below a dam where the river
spreads out and becomes shallow, the bed of the stream is strewn with
pebbles and rooks The upper surfaces of the larger stones are covered
with dense mats of Fontinalis, one of the mosses whioh grows profusely
when completely submerged The flow of water over these rocks is quite
rapid but, nevertheless, silt becomes lodged between the closely packed
moss leaves When one of the rocks is removed from the water and allowed
to dry for a few minutes Tricorythodes albilineatus nymphs begin to crawl
slowly about fl^oking their tails over the abdomen just as do most of
the other nymphs which possess operculate gills If the moss is examined
while it is quite wet, the nymphs are very difficult to see, their move
ments being very slight until the drying action begins to take effect
The Santa Fe River below* and to some extent above, the dam is nor
mally ohoked with Vallisneria, Sagittaria, and Pais. Frequently, when a




217
The nymphs of Habrophlebioda s and ]?_ volitans are very similar and
are easily confused unless examined carefully. The easiest method of
distinguishing between them is by means of the gills. In volitans, the
gills each bear a bifurcate trachea whioh has no lateral branches; al
though the gills of Habrophlebiodes brangelpennis also have bifurcate
tracheae, there are also prominent lateral branches from the main trunks,
DISTRIBUTION! There is nothing in the appearance of volitans to suggest
that it is an unusually vagile fora, yet it has been taken over an area
stretching from Ontario to Florida, The species has been recorded from
the Coastal Plain at Fort Valley, Georgia, close to the Fall Line, but
all other published records are more northern*
In Florida, P. volitans, Blasturus intermedius, and Ilabrophlebiodes
brunneipennis have an almost identical distribution over the northern por
tion of the state, Volitans extends southward only to the area around
Gainesville; eastward, it has been taken in the western part of Nassau
county; westward to the state border and on into Escambia and Baldwin
counties in Alabama, (See
ECOLOGY: The ecological distribution of volitans is almost identical
with that of ilabrophlebiodes brunneipennis, Ide (1930:207) and Gordon
(1933) allot a few brief sentences to a discussion of the environment of
volitans, Ide (1935) studied the effects of temperature on the distri
bution of mayflies in a stream. Although volitans is present in the area
in which Ide worked, he did not mention its occurrence in any of the streams
that he examined, however his conclusions, drawn in part from a study
of other species of Paraleptophlebia, are very interesting, particularly
the following, "The faots brought out by this study appear to throw some


£9
46'
(ills single on all abdominal segments (see figs 45 and 46)
Cloeon nyssa


426
decrease in the size of the body, without a. corresponding decrease in the
size of the legs; reduction of size of gill lamellae; reduction of middle
oerous from a length two-thirds the other two, to a mere rudiment* The
reduction of this cercus is, no doubt, of importance in reducing the pull
cf the water, by reducing the exposed surface in this part of the body, while
the remaining two, when held close together, as they commonly are, serve to
complete the pointed tip of the tapering body*
Examination of the alimentary canal of Several nymphs indicated almost
nothing concerning the food habits of the species, for in every case the
food had been so thoroughly masticated that identification of the frag
ment s was impossible* However, since diatoms and algae were so common on
the rocks and plants inhabited by the nymphs, these were undoubtedly the
food cf the insects*
LIFE HISTORY* No nymphs were reared through the entire life history, but
a study of the species in a small stream on the campus of the University
of Florida leads me to believe that the life cycle occupies a period of
about six to eight months. Inn area of the stream was thoroughly collected
until nc nymphs except very immature specimens could be found. About six
months later, the stream was again examined and it ivas found that mature
as well as very young nymphs were present. Although individuals intermediate
in size were also discovered, these might well have been offspring of adulte
emerging in other parts of the creek than those examined*
Emergence of the subimago occurs from about two to five p* m. This
emergence time has been noted both in the spring and in the late fall, the
only two periods during which specimens have been reared or observed emerg
ing in the field. Then ready to transform, the nymph swims to the surface,


287
DERIVATION OF THE SPECIES: Although. I have collected, from streams in
Alabama as far north ns A'etumpka, no other nymphs of E. hirsute, were
seen. It would, however, seem likely that the species is derived frcm the
attennata stock and lias come south from the Appalachians. The nymphs have
become adapted to the rather slow waters of the Coastal Plain, and may even."
tually become much more widespread just', as E trilineata has done
LOCALITY RECORDS: Escambia Co, Alabama Perdido creek, about 2/£ miles
north of the Florida-Alabamn state line (April 5, 1058, E H H, and L. J.
M, nymphs)


1X6
filled Tilth yolk, and the nymph oan survive on this material for as long
as two days. The most noticeable part of the insect is its enormous head
with the five eyes, the only really dark part of the body.
Thigmotaxls and phototropism are present when the nymphs are hatched,
and the immatures can be seen running about seeking darkened places and
clinging tightly to the object on which they are situated*
The movement of the young nymphs, just as in the more mature insects,
is as readily backward, sideward, or forward accoring to the direction of
the stimulus.
I have observed the mating flight of this species several times and
each time it was essentially the samo. Just before dusk, a small band of
approximately ten to twenty males gather directly over a stream, whether
it be small or large makes no difference. The characteristic flight is
then begun about twelve to fifteen feet above the water. The horizontal
flight is slight; the vortical rise and fall is about two feet. The flight
was observed in May at 7:00 p. m. and in early July at 8:00 p. m. j in the
spring, it occurred at 3:15 p m. There is a definite correlation between
amount of light and the time at which the swarming takes place. The time
that the flight lasts was not determined because the insects were still
flying when darkness fell; however, from the fact that the females begin
to oviposit while it is still light, it would seem that mating ceases very
shortly before, or after, dark.
The forward flight of the males was not much over eight to ten feet
with a rapid return to the original position. Occasionally a female would
fly into the swarm and be immediately seized by a male. These two then
separated from the swam and were usually lost to sight, but some were seen
settling to the ground where they soon separated, the male returning to the


365
diatom is picked up along with the filaments.
LIFE HISTORY Life as a nymph probably lasts between six and nine months
When the subimago is ready to emerge, the nymph swims to the surface, the
thoracic covering splits, and in an instant the subimago rises from the
water This is particularly necessary in streams,for if the adult is
thrown off balance and the wings wetted, they crumple when freed from the
waters the insect is then doomed, for it cannot again straighten them
The subimago rises from the water, flies upward and may reach a support
close to the stream, but usually the flight is upwards until the insect is
out of sight some twenty-five feet in the air* It probably flies, then, to
trees which line the stream margin and here it quietly sits and awaits the
ultimate molt. The shedding occurs within eight or nine hours Adults
have been observed in the field emerging just after sunset, and in the
laboratory the performance is the same Nothing is known of the mating
flight or oviposition
DERIVATION OF THE SPECIES* When the known distribution of A ephippiatus
is examined, it seems that the speoies was probably derived from a northern
form whioh migrated southwards through the Appalachians and gave rise to
ephippiatus in the foothills of this province From there, it was but a
step to migrate into the Piedmont and thence along the Apalaohicola river
drainage system into Florida; its spread in Alabama by way of the Mobile
river could easily have paralleled its entrance into Florida Once in
the Floridian panhandle, its dispersal was easy, for the speoies oan tolerate
mildly acidic and mildly basic streams* However, its rarity in the waters
of north and oentral Florida is as yet unexplainable
LOCALITY RECORDS* Alachua Co Hatchet Creek (April 2, 1938, L B, adults;


152
have also been oollected as far west as the drainage of the Yellow River
in Okaloosa county. The speoies is known with certainty only frcm the
western part of the state, and, in this region, is confined principally
to the Apalachicola river system.
It seems strange that such a large and apparently adaptable and
tolerant species should be confined to such narrow geographic limits.
The presence of other species of the same genus, which are obviously so
similar, in the same drainage system leads me further to doubt the valid
ity of'the species.
A single female Hexagenia was oollected in the Ooala National Forest
by Professor Hubbell end Mr. Friauf which seams to be K weewa in that
the dorsal markings are very indistinct and limited* In fact, the markings
are even more indistinct and more limited than on typical weewa., but since
the speoies is not definitely known from this area exoept for this one
female, it will not be considered an east Florida species* (See o-uvp z),
ECOLGttYi The immatures are burrowers in the silt of stream margins* It
is rather easy to locate the nymphs because many of them leave small round
hole8 leading into their burrows. If there is a rather large deposit of
silt in quiet water, there may be many of these openings over a comparatively
small area. Holmes Creek, in western Florida, offers an ideal situation
for the development of the nymphs, and it was at this stream that I found
them more common than at any other locality from which the insects have
been collected* Here, the water flows slowly over a very silty bottom.
Vegetation grows profusely in the stream bed, but in places where the cur
rent is slightly more rapid, the floor is bare exoept for the silt. At
the time of collecting, the water was quite low, not more than a few inohes


384
and several nymphs were found in this material#
The principle mayfly associates of intercalaris are B* spinosus, B*
splethi, Pseudooloeon alachua, P* dubium# P. parvulum# Centroptilum virid-
ocularis, C* hobbsi, Stenonema smithae, S* exiguum, S* proximum, Tricory-
thodes albilineatus, Isonychia spp., Caenis hilara# and Qreianthus sp* No* 1*
SEASONS* Baetis intercalarla emerges throughout the year# but there is
evidence of a tendenoy to form broods within a particular stream. Those
collections from the Santa Fe river seem to indicate that March and October
are important months for emergence because the mature nymphs were very common
during these periodsj however# mature nymphs were also found on other dates
but not in such numbers. Nymphs collected from Sweetwater creek in west
Florida were predominantly in the last nymphal stage during December# but
mature nymphs were also present in all ouher months in which collections
were made there*
The type specimens of B. intercalaris were taken by MoDunnough at
the Rideau river, Ottawa# on June 11 through the 14. In 1922, he collect
ed again at the type locality and noted that there were apparently two
generations# one emerging in early June and the other from the middle of
August until early in September* MoDunnough also noted that individuals of
the second generation were somewhat smaller than those of the first*
Ide (1935) working in Ontario on the effect of temperature on the dis
tribution of mayflies in a stream, found that in the lower, warmer reaohes
of the stream, interoalaris gave definite evidence of the occurrence of
two generations in the same season, the first during the early part of June,
the second starting in July and proceeding until the middle of August.
Collections from the upper part of the stream indicated that there is pro-


229
HABRPHLSBIODES Ulmer
Ulmer established Habrophlebiodes in 1919 * including betteni
and americana chiefly on genitalia characters and peoularities in the
shape and venation of the metathoraoio wings. At present, the genus is
known to inolude four species which can be placed in two groups, the first
includes betteni, americana, and brurmeipeimis,and the second annulata.
Betteni and american are very similar have even been regarded as synonymous.
H. brunneipennls, although resembling them in genitalia, differs in other
characters, principally wing color.
The speoies of Babrophlebiodes are widely distributed over the eastern
part of North America and in the southwest. H. betteni is known from
Quebec and North Carolina} americana from Ontario to South Carolina}
annulata has been collected in Oklahoma} and my work has revealed the
presence of an undesoribed speoies, here called brunneipermis, in southern
Alabama and in Florida. This discovery is not particularly to be wondered
at, sinoe the Coastal Plain has been consistently neglected by the Ephemerop-
terists. Mountainous and hilly regions are the ideal places to secure
abundant and varied oolleotions, but it now begins to be evident that the
Coastal Plain, likewise, has its interesting forns. The Appalachians
at present constitute the region of greatest apparent abundance for the
species of the genus, but future collecting may well show that speoies of
Habrophlebiodes are common throughout the mid-portion of the continent.
There is as yet no reason to suppose that they have spread westward into
the Rocky Mountains.
Habrophlebiodes, liabrophlebia, Choroterpes, Thralus, and Thralodes
among the Leptophlebiinae are all closely related, and are most likely


323
that this left the apeles that had been associated with harrisella under
the name Caenis (properly Braohycercus) without a generic name, since
Caenis liad been "invalid from, the boginning#" But this is inoorreot ;
it assumes that Curtis* inclusion of harrisella in Caenis (Braohycercus)
invalidated Caenis s 1*, while in reality the type of Caenis s# 1. must
be chosen as one of the two species iaoluded by Curtis under Caenis (Caenis)#
The genotype of Caenis was validly designated by Curtis in 1337 as
macrura# Campion called the generic unit,supposedly in need of a name,
Ordella, giving macrura as genotype; this name must therefore be regarded
as a strict synonym of Caenis Stephens# In 1931 (d) Lestage reaffirmed the
synonymy of Eurysaenis with Braohycercus# North American students of
the Ephameroptera have not accepted Ordella, though Braohycercus has been
substituted for Eurycaenls# The present status of these names is therefore
as follows*
Braohycerou8 Curtis 1334, genotype by monotypy B# harrisella Curtis*
3yn# Cttycypha Burmeister 1839, genotype here selected Oxyeypha
luctuosa Burmeister (s Braohycerous harrisella Curtis,
according to Eaton and Campion)*'
Syn# Euryoaenis Bengtsson 1917, genotype by original designation
feraohyoerous harrisella Curtis#
Caenis Curtis 1836, genotype Caenis (Caenis) macrura Stephens, desig
nated by Stephens 1837
Syn# Ordella Campion 1923, genotype by original designation
Caenis macrura Stephens#
In 1931, MoDunnough treated the North American species of the family
Caenidae but apparently did not know of Campion's and Lestage's placement
f Euryoaenis in synonymy, since he described prudens as Euryoaenis prudens.
Traver (1932) likewise overlooked these papers, but in 1936 she used


409
Cloeon rubroplotun McDunnough
TAXONOMY- A series of nymphs from Florida are being tentatively referred
to cloeon rubropioturn. Although several attempts have been made to se
cure adults of this species on collecting trips into its range, only nymphs
and one female ware taken Specific identification of nymphs in the Baetinae
is a rather risky undertaking, particularly since the nymphs are so poorly
known* I communicated with Dr* F* P* Ida concerning the identity of my
specimens, but at the time had so few of them that I could send only
sketohes of pertinent structures to him. The following is from his letter
in reply* "Frequently in some species the third segment of the maxillary
palp is lost beoause of very intimate fusion of the parts. I do not know
whether this is the case or not. In regard to the gill character which
you mention [presence of a recurved flap on the first pair of gills] I
find that in my specimens of Cloeon rubroplotum MoD. the first gill only
is double, the rest single. Clemens' description of the nymph of C. dubiun
(1915 *..) probably is the description of C. rubropictum.11 Later, young
nymphs were collected in whioh fusion of the segments of the maxillary palps
would not be expected, and it was found that in these, as in older nymphs,
only two segments were present. Whan all points are considered, it is rather
unlikely that the Florida nymphs are C. rubroplotum) the distributional
data presented below tend to bear out this conclusion. For the time being,
I believe it best to consider the nymphs under this name. C. rubropictum
does not oonform to the definition of the genus as given by Traver (1935:
733) sinoe instead of having gills double on all segments or segments 1-6,
they are double only on segment 1 (C. minor and C. triangulifera also form
exceptions).


"'.04
immatures are not well suited to such a situation and apparently shun it
whenever a tetter place is offered.
Sise of the stream offers no obstacle to snithae nymphs as is in
dicated by their presence in permanently flowing water which ms no more
than two inches deep and one foot across (at low water),as well as in
large rivers such as the Suwannee. Rate of flow is likewise not of par
ticular importance^ for the nym.-hs occur in almost stagnant as well as the
most rapidly flowing of Florida streams, of which the Santa Fe river is
probably the sxviftest* In this latter river the nymphs are very numerous
on the undersides of the rocks that are strewn over the stream bed, buth
they are much leas numerous on the Vallisnorla and other vegetation which
form, huge mats* The current in this river, just below the dam at Poe
springs, is very rapid but even so the nymphs are very common even in the
swiftest water; at the shore, bhe flow becomes negligible but immatures
are almost as numerous here as in the rapids. Pepths to which the nymphs
descend, as far as I have been able to determine, ara somewhat limited by
the materials available for support and the amount of flow, but it is
likely that the nymphs do go fairly deep in the larger rivers.
It has bson found many times that the nymphs had occupied areas
where the current was rather strong at high water, but as the level of the
stream fell and the movement of the water became less vigorous, the nymphs
did not migrate into the swifter parts but remained in the almost stagnant
portions left behind by the receding flood. In some oases this had ever-
gone so far that nymphs were found to be isolated in small pools cut off
from the main stream, and. here they lived on leaf drift and other debris
which accumulated in the bottom of the pool.


18'
19 (12*)
19'
20 (19*)
20
21 (20)
21'
Paraleptophleb la brad ley 1
All gills narrow bifurcate lobes not separated to base; no
lateral branches from tracheae (see fig, 18). Dorcua unioolorous,
Paraleptophlebia volitans
Claws of Middle and hind logs long and slender, about as long
as the tibiae $ claws of ore legs differ from others in struoture
(in being doubled see fig. 19).
('!etretopirme) fiphloplecton spoolosum
Claws of all legs similar sharp pointed much shorter than
tibiae.
(20)
Posterolateral angles of apical abdominal segments prolonged
into thin, flat, spines, fore legs conspicuously fringed with
long hairs. Gill tufts present 'on bases of maxillae and fore
coxae.
£3iphlonurinae) Isonychia (21)
Posterolateral angles of apical abdominal segments hardly more
than acute, not prolonged into thin, flat spines. TTc gill
tufts on maxillae and coxae.
Baetinae (32)
Antennae crossed by a brownish band about l/S distant from the
base.
An.annae without such bands.
(22)
(23)
22 (21) Grayish area on outer margin of each gill plate.


SOI
wings began in the Jurassio* Reduction of the number of segaents in the
foroeps of the male to a single one further bears out the idea that the
genus is an advanced onej however, the eyes of the male have not become
enlarged as in many other members of the order, but have remained rather
close to the primitive ancestral type* "The distinctive characters of
Gaenis indicate that it has been removed from the rest of the order for
a long time*" (Spleth, 1933i 356)* Of oourse, this statement must be
expanded to include other members of the subfamily which Bhare, in com
mon with Caenis, the characters mentioned above*
Caenis diminuta Walker
TAXONOMYi Francis Walker described this minute form in 1853 from speci
mens collected at "St* Johns Bluff, Florida" (a point on the sotrth side
of St. Johns River about six miles from the ocean)* Since then, the
speoies has been redesoribed by Hagen (1851s 55) according to whom it
is related to C* laotea of Europe? by Eaton (1871 95 and 1884: 147),
by MoDunnough (1931: 257), and by Traver (1935i648-849)* All of these
authors agree that the speoies is quite distinot, but MoDunnough and
Traver have shown that in addition to the true diminuta, the material
of earlier writers also included five other species* The adults of
C. diminuta may be distinguished from all other North American speoies
of Caenis by the dark stigmatio streaks present on the anterior abdominal
tergltes, by the presence of a dark apical band on the hind femora, and
by the absenoe of the blaok dots from the femora* Nymphs of Caenis are
almost impossible to separate, but if only the two Florida species are


209
only the size of the particles acts as a deterrent. Feeding is an almost
continuous process.
Nymphs are more or less negatively phototropic while the reverse
is true of the subimago and imago. In the laboratory, nymphs seek the
dark underside of any materials in their container during the day and
whenever artifioial light is caBt on them. If left in a dark room, they
soon find their way to the upper surface of the leaves but as soon as a
light is turned on, they again scurry away into some dark crevice* Nymphs
about to emerge undergo a phototaotic reversal, and crawl to the upper
side of leaves or onto sticks, logs or any other available support which
is near the surface of the water.
LIF3 HISTORY: The length of nymphal life is unknown, but would seem to be
one year. This assumption is based on the concentration of mature nymphs
curing one definite period* Many mature specimens have been reared to adult
hood in the laboratory, but 1 have found it rather difficult to keep younger
nymphs alive for more than two months*
Just previous to metamorphosis, the mature nymph moves to the surface,
still slowly vibrating its gills. With its mesothorax projecting from the
water, it begins to strain and the effects of this straining are soon
evident, for a longitudinal split appears down the thorax. Pulling mightily
by bracing itself against the nymphal skin, the subimago gradually extri
cates the wings from their sacs, all the time moving its abdomen from side
to side, a movement apparently caused by the tremendous exertion necessary
to free the body from the nymphal exuviae. As the wings are pulled free,
it can be seen that they are inverted, i. e. the costal border faoes ven
tral ly. The sudden release of the wings causes them to snap into place


391
drift, and somewhat more frequently on submerged logs in the current*
£U spiethi nymphs are the most toleraht of all the Florida species of
the genus* I liave kept nymphs alive in a shallow pan of water without aera*
tion for a3 long as a week, and they have remained alive in an aerated
aquarium for as long as fourteen days* Percentage of nymphs transforming
in an aerated aquarium is usually greater than in the other Baetis species
except perhaps spinosus*
Although nymphs of spiethi do inhabit basic streams, they seem to thrive
to a much greater extent in eiroum-neutral or slightly acid creeks* These
usually have a high content of humic and other organic acids which give the
water a dark tinge, but this does not seem to be harmful to the insects*
The ephemerid nymphs associated with this species are the same as those
listed for B* spinosus*
Adults are often encountered in spider webs under bridges. The bridges
are also the most productive places for secur ng free adults or subimagos,
since the humidity over the streams is fairly high and shade is plentiful,
two qualities which the subimagos and adults seem to demand* Apparently,
the subimagos of Baetis can tolerate a much dryer atmosphere than can the
Leptophlebines, for they can molt where the Leptophlebines would perish*
SEASONS seasonally, this species is not restricted* While emergence is,
of course, greater in the summer than during the colder months, no month
is entirely free of adults* The evidence for this statement is conclusive,
for I have adults for ten months, February through November, inclusivej
furthermore, last instar nymphs were taken during the early part of December
and the early part of January, and these nympns would, without doubt, have
emerged sometime during the seoond week of these months*


423
6 x 4") was the largest of Pseudooloeon that I have ever found in such
a small area at one time# The saaller stones (really pebbles) usually
have one or two nymphs on eaoh, and on them the nymphs seem to prefer the
downstream side.
Other sand-bottom streams which laok stones have relatively few nymphs
in comparison to the Baetis fauna. Only an occasional specimen is collect
ed from the vegetation in the swiftest water The nymphs live on the distal
parts of the plants which swing free in the currentj very rarely specimens
have been collected frora submerged logs, but the most productive areas are
the small pebbly riffles which are occasionally exposed in the sand bed.
itn interesting feature of uhe riffles is the fact that many of them are
of only a temporary nature yet they have the typical riffle fauna
In numbers of individuals, P alachua is rather scarce compared to
B* spinosus in the same stream In every case where the two species were
collected at the same time, many more of the latter than of the former
species were found, even in the riffles and on the rocks.
In the Canta Fe river, described elsewhere in this paper, the nymphs
are more plentiful than they are in the sand-bottom streams. In this river,
Rainbow Springs run, the Withlacoochee river, and the Hillsborough river,
as well as other streams which have rather dense growths of Vallisneria in
their beds, P. alachua nymphs seem to find very suitable conditions. The
nymphs may be foimd on the free ends of the leaves of Vallisneria where it
grows in the swiftest water, but they are also frequently found in slower
wat or in smaller numbers.
The acidity or alkalinity does not seem to affect nymphs materially
if it does not range below 6.0 or above 8.0. Both of these pH values are




297
the Bpecies of this genus, it is rather difficult to arrive at any hypo
theses as to the derivation of T* albilineatus. The whole genus is such
a closely knit group that there has apparently been little evolutionary
change since its origin* T* albilineatus is probably most closely related
to T* atratus and T* allectus* If Tricorythodes is distributed over the
Coastal Plain, as I believe, albilineatus may have arrived in Florida
through the more rapidly flowing, basie streams of this province* T*
allectus is known to occur in West Virginia in the heart of the Appala
chians* It may be that albilineatus has been introduced into Florida
through those streams which drain the foothills of this mountain range*
Until far more collecting is done in the southeast, ideas concerning the
origin of this species must remain of a very speculative nature*
LOCALITY RECORDS* Alachua Co* Santa Fe River at Poe Springs (May 14,
1934, J* S. R., nymphs* May 21, 1934, J* S* R., nymphs* March 19, 1935,
A* M* Laessle, nymphsi Maroh 24, 1937, L* B*, nymphs* March 12, 1938,
L* B*, nymphs & adults* March 18, 1938, L* B*, adults* May 14, 1938, L. B*,
nymphs* February 11, 1939, L* B*, nymphs & adults* February 18, 1939,
L. B*, adults* Maroh 4, 1939, L* B*, adults* March 25, 1939, L* B*,
nymphs and adults* October 25, 1939, L* B*, nymphs and adults* April
6, 1940, L* B*, nymphs and adults)* Bay Co* 27*4 miles n* St* Andrews
(May 30, 1940, L* B*, nymphs)* Pine Log Creek (May 31, 1940, L* B*,
nymphs). Citrus Co* Withlacooohee River (April 2, 1937, L* B., nymphs)*
Gadsden Co* 10 miles S* River Junction (July 1, 1939, L* B*, nymphs)*
Gilchrist Co* Suwannee River at Fannin Springs (April 5, 1938, L* B*,
nymphs)* Hernando Co* Southern county line (March 27, 1938, L* B*,
nymphs)* Weekiwatohee Springs (August 20, 1938, T. H* Hubbell & J* J*


41
in this area But this too may be explained on the basis of temperature,
if these southern forms arose in the cold -waters of the southern Appalachians
or the hilly regions of the Piedmont. The only truly seasonal species
are Oreianthus sp# lio# 1, Baetisoa rogersi, Camp sums incertus# Iexagenia
vreem and probably the other species of Hexagenia, Ephemera simulans. Ephem-
ore 11a trilineata, and perhaps a few others#
ZOOGEOGRAPHY
The topography of Florida has recently been described by Cooke (1939)
in his "Soenery of Florida." He divides the state into five natural areas
(see map 1) and these have been found to be olosely correlated with differ
ences in mayfly fauna* A discussion of the divisions of Florida can be
found under the section on ecology#
Since mayflies are so limited ecologically# introduction into a new
area is subject to many obstacles# The many factors influencing drainage
are the dominant elements directing the movement of primarily aquatic in
sects# It has recently been suggested (Hubbell and Stubbs in Carr, 1940)
that i
1* An area in central Florida has persisted, in the form of large
islands or a group of keys, at least since the beginning of the
Pleistocene# and probably since Fliooene times*
2* The bridging of the gap to the mainland on one or more occasions
(perhaps first in the Pliocene), followed by renewed insular iso
lation*
3* Final establishment of peninsular conditions during the Pleistocene*
More or less extensive marginal submergences in late Pleistocene,
4


440
Clemens, W* A. 1922. A parthenogenetio mayfly (Ameletua ludens Needham)*
Camad* Ent* 54* 77-78.
Comstock, J* H* 1936* An introduction to entomology* Comstock Publishing
Co*, Ithaca.
Cooke, C. W* 1939* Scenery of Florida. State of Fla. Dept* of Conserva
tion* Geol* Bull* No* 17. Fp. 1-118, 58 text figs.
Cooke, C. W* and Mossom, S* 1929* Geology of Florida* Florida State
Geol. Survey. 20th Annual Report* Fp* 29-228, plates 1-29*
Cooke, H* G* 1940* Observations on mating flights of the may-fly Stenoneaa
vlcarium (Ephemerida)* Ent* News. 51* 12-14, 1 text fig*
Dodds, G* S* and Hisaw, F* L. 1924* Ecological studies of aquatic insects*
1* Adaptation of mayfly nymphs to swift streams* Ecology* 5t 137-
148. Plates 1 and 2*
Eaton, A* E. 1883-1888* A revisional monograph of recent Ephemerldae
or mayflies. Trans. Linnean Soo* London* Second Series Zoology.
Vol. 3, pp. 1-352, plates 1-66*
Eaton, A* E* 1892. Ephemeridae in Biologa Centrali-Amerioana. Pp* 1-16,
1 plate.
1896. Ephemeridae in brackish water. Ent. Sag, p. 144.
Felt, E. P* 1901. Aquatic inseots of the Saranac region. New York
tate Mus. Bull. Report for 1900. Pp. 499-532, 14 text figs.
7 plates.
Forbes, S. A. 1888. Studies of the food of fresh-water fishes. Bull.
Ill. State Lab. of Nat. Hist. Vol. II, Art. VII, pp. 433-473.
Frison, T* H* 1935. The stoneflies, or Pleooptera, of Illinois. Ill.
Nat. hist. Sur. Bull. Vol 20, Art. IV, pp. 281-471, 343 figs.
Gliok, P* A. 1939* The distribution of inseots, Bpiders, and mites
in the air. U. S* D. A* Techo Bull. No* 673. Fp. 1-150, 13 text
figs. Plates 1-5.
Hagen, II. A. 1861. Synopsis of the Heuroptera of North America with
a list of South American species. Staithsonian Mise* Collections.
Vol. IV, Art. I, pp. 1-347.
Hobbs, H* H* 1940. A contribution toward a knowledge of the crayfishes
of Florida with special reference to their ecological and geographio
distribution* Ms* of Doctoral dissertation, Univ* of Fla* Pp* 1-259,
plates 1-6, maps 1-12*


362
or mor longitudinal veins and a small costal process; medium-sized wings
usually with three longitudinal veins and a rather large, hook-like costal
process; and smaller hind wings with two longitudinal veins and usually
a small costal process. From the standpoint of nymphs, other lines of
development may be evolved those nymphs with three caudal filaments and
those with but two The former group can be further subdivided into those
possessing rounded seventh gills, and those with lanceolate seventh gills.
Again, the former group can be subdivided into those speoies with an ex
panded second segment of the maxillary palp and those in which this segment
is not expanded.
Eoologioally, the nymphs are confined to water in which there is constant
motion* In Florida Baetis nymphs occur only in streams, but in more northern
localities the immatures can tolerate lake shores where there is continuous
wave action*
Baetis spinosus MoDunnough
TAXONOMY MoDunnough described Baetis spinosus in 1925 from specimens
collected in the Canadian province of Manitoba. The species remained un
noticed until 1935 when Traver recorded adults from New York and the Chatta
hoochee river at Atlanta, Georgia.In 1940, the description of B* spinosus
was completed with the publication of descriptions of females and nymphs
from Florida (Berner, 1940 c).
B. spinosus is quite distinct from all other species of the genus
in its genitalia whioh MoDunnough (1925b; 174) says "are, however, very
characteristic, the second joint of the forceps having a strong pointed
projection on the inner apical margin, a feature whioh is unique in our


126
adults; February 11, 1939, L B., nymphs and adults; February 18, 1939,
L. B*, nymphs and adults; February 28, 1939, L. B. # nymphs and adults;
March 25, 1939, L. B., nymphs and adults; October 3, 1939, L. B., nymphs
and adults; April 6, 1940, L. B, nymphs and adults); Santa Fe river at
U. S, Hwy* $41 (May 14, 1938, L. B., nymphs); Hatohet creek (October 28,
1939, L. B., nymphs)* Bay Co. 16*8 miles north of Panama City (June 8,
1938, L* B., nymphs); Pine Log Creek (H. H. H. and L* B., May 31, 1940,
nymphs). Citrus Co* Withlaoooohee river (L. B., April 2, 1937, nymphs).
Escambia Co. Perdido creek (April 5, 1938, H* H* H* and L* J. M,, nymphs);
Bayou Marquis (June 1, 1940, H* H* H* and L* B., nymphs). Gadsden Co.
4 l/2 miles south of River Junction (March 17, 1939, J* S, R., H* H. H.,
F, N. Y., L. B,, nymphs). Gilohrist Co. Suwannee river at Oldtown
(April 1, 1938, L. B., nymphs and adults; April 19, 1938, L. B., adult).
Hillsborough Co* Bell creek (March 26, 1938, L. B., nymphs); 2 miles
west of Alafia (Maroh 26, 1938, L. B., nymphs); Hillsborough river state
park (August 18, 1988, T. H. Hubbell and J* J. Friauf, adults); Hillsborough
river (February 11, 1939, L. J. M., nymphs; October 21, 1940, L. J. M.,
adults). Jackson Co. Blue Springs oreek near Marianna (December 11, 1937,
L. B., nymphs; June 9, 1938, H. H. H*, F. N. Y., L. B., nymphs; July 1,
1939, L. J. M., L. B., adults; June 5, 1940, H. H. H. and L. B., adults);
3.6 miles north of Altha (June 9, 1938, L. B., adults); 12.2 miles south
east of Marianna, (June 9, 1938, L. B., nymphs). Jefferson Co. (April
1, 1988, H* H* H. and L. J. M., nymphs). Liberty Co. Sweetwater oreek
(June 10, 1938, L. B., nymphs; November 4, 1938, L. B., nymphs; December
1, 1939, H* H. H. and L. B., nymphs; December 1, 1939, H. H. H. and L. B.,
nymphs and adults). Madison Co. At Jefferson county line, Auollla river


231
from slow-flowing, silt-bottom streams. If leaf debris is scarce, the
nymphs may tend to gather on vegetation near shore where they are fairly
well protected. Any portion of the stream where the current is moderate
to slow, and in which there is either vegetation or leaf drift is a likely
refuge for brunneipennis. ilymphe have never been taken from rivers nor
large streams, but occasionally, they occur in medium-sized creeks and
are most common in small brooks. Their abundance seems to be in an inverse
ratio to the size of the stream. The small brooks flowing through the
ravines of the Tallahassee Hills have a mayfly fauna consisting almost
entirely of brunneipennis, but the species is much less frequently encounter
ed in the larger streams of this area.
The well-tracheated, yet not very large, gills allow these nymphs a
great deal of freedom in moving from one part of the stream to another.
I have studied this species most thoroughly in a small sand-bottom creek
about two and one-half miles west of Gainesville. The nymphs are exceeding
ly common here, particularly in the leaf drift along the margin of the
stream and in quiet pools. Roots of terrestrial plants are exposed ever
large areas in the bottom of this brook, forming a dense mat, and in this
mat the nymphs are easily located. Among the roots, the immatures probably
become dingers rather than sprawlers, because the current is much swifter
over these root beds then in the leaf drift. Brunneipennis nymphs, in the
earlier instars, may often be found among the pebbles in riffles, but they
are less numerous in this situation than in quieter, more silty zones*
The streams inhabited by this species drain heavily wooded areas, and
in consequence are usually somewhat acid and tinged with brown. Temperatures
in the streams rarely fall to freezing, and then only in the almost stagnant


129
form I am calling S. proximum).
S. proximum is the only representative of the interpunctatum group
of Stenonema found in Florida. Both in the nymphal and adult stages, the
insect is quite distinct from the members of the trlpunctatum-pulohellun
group as it occurs in this area. This distinction has been pointed out
in the key.
DISTRIBUTION* Traver described S proximum from a series of adults and
nymphs collected near White Church, New York. At the same time she men
tioned having specimens which seemed to be of this species from Ithaca
and Honeoye Falls, New York and Lake Forest, Illinois. S. proximum has
been found to be generally distributed throughout Florida wherever there
is pennanently flowing water. AdultB and nymphs have been taken in Hills
borough county in the west-central part of Florida and northwards to Burke
county, Georgia. The species is known to extend from Nassau county, Florida,
to Mobile county,Alabama.
If the Florida speoies is proximum, the distribution certainly seems
unusual. If, on the other hand, the Florida specimens are interpunctatum
or pallidum, the distribution is much more easily explained, for both of
these speoies have been previously recorded from the southeast. Such a
great break in distribution does not seem consistent, unless it will later
be proven that all three of these speoies can be inoluded ander one name,
interpunotatum, and perhaps be designated as merely varieties or, at the
most, subspecies.
Only twice before 1ms a species of Stenonema belonging to the inter
punotatum oamplex been reported from the Coastal Plain. In 1933, Traver
mentioned the occurrence of S. interpunot at urn (?) in Goshen Swamp, Duplin


134
strated by the presence of gills These nymphs differ from the first in
star of smithae in that they are reddish brown, while the smithae nymphs
are white* For three more weeks some of the nymphs remained alive,but
very shortly after this, all had disappeared# Growth during these three
weeks was rapid, the nymphs developed additional gills, more spines on the
femora, the oaudal filaments elongated, and the thorax became much more
robust*
The postembryonic development of S* interpunotatum has been studied
to some extent and the results published in the "Biology of Mayfliesj"
only the first eleven instars are described and the statement is made
that the remaining nymphal instars show only increase in size of the various
body parts Wo mention is made of the actual number of instars through which
the nymph must go#
DERIVATION OF THE SPECIES: Entrance of S proximum, if the Florida species
is proximum, was probably made into the state by way of the Mobile, Apala-
chocola, and Suwannee river drainage systems. Even if the species does
prove to be interpunctatum or pallidum, the entrance might well be the
same. Most likely the species is of northern origin, but due to its vagil-
ity has spread southward to become one of the dominant stream mayflies
in Florida.
LOCALITY RECORDS* Alachua Co# Lake Santa Fe (April 7, 1937, L B, nymphs
and adults; January 30, 1940, L. B, nymphs, adults reared February 4, 6,
7, 10, 12, 13, 15, IS, 18, 21-23, 26, 27, 29, March 2, 7, 13, 14, 20, 21,
April 2)i Hatchet creek (March 23, 1938, L. B., nymphs and adults; April
2, 1938, L B, nymphs and adults; April 18, 1938, L* B, nymphs and adults;
May 5, 1938, L* B, nymphs and adults; Wovamber 13, 1938, L. B., adults;


309
12/4/39 Killed ten specimens from dish #4* All -were healthy and
apparently growing* Two nymphs were seen which were very immature, hardly
larger than a week old nymph this may have been due to delayed hatch
ing*
2/7/40 When preparing dishes with C* diminuta eggs on 10/23/39, a
few eggs adhered to the vial in which the females were brought into the
laboratory* I had filled the vial with water, added a pinoh of dried
organic matter and then completely forgotten about it* Today, while
oleaning up, I found this vial* The water was almost gone but interesting
ly, there were seven Gaenis nymphs still alive and vigorous but they were
all DWARFED. Two of these nymphs had not even developed gills but merely
a pair of tubular outpooketings on segment 1 (or 2 ?)* This stmating is
evidently the result of insufficiency of foot the small mass of material
which I had placed in the bottle in October was still hard packed and
apparently has only been nibbled at by the nymphs*
2/19/40 Four nymphs of £ diminuta are still alive (these are
all that remain of those hatched IO/30/39), three of whioh are in the
last instar. One of the nymphs measures 4*6 mm, another is about two-
thirds grown.
2/24/4O Wing pads of one of the nymphs that hatched 10/30 beginning
to blacken*
3/3/40 Found one nymph (10/30/39) almost ready to emerge.
3/4/40 Adult C* diminuta ¥ (10/30/39) floating on surface of
water and shed nymphal skin of another imago in the dish. Apparently
both emerged yesterday in the afternoon or last night.
The above table along with the notes gives a partial pioture of


369
is more pronounced in the subimaginal stage Orientation is definitely
negatively geotropio, both tho subimago and imago clinging with head up
ward
LIFE HISTORYi Although repeated attempts have been made to hatch eggs in
the laboratory, none have been successful* The females which were forced
to oviposit may not have been fertilized, for none was taten in flight*
Artificial fertilization was also tried, but it, too, produced no results.
So far as published data are concerned, they reoord the rearing of only a
single species of Baetis* B* vagans was raised from egg to adult in the
laboratory and in the fieM at Ithaca, New York by Dr* Helen Murphy (1922)*
She found that under laboratory conditions, the nymphs went through twenty-
seven instars, and, according to temperature, this developmental period
was six to nine months definite broods being produoed which emerged in
May, August, and October In Florida, no such brooding has been observed
and would not be expected of B spinosus, and consequently no correlations
can be made such as those very intersting ones found by Dr Murphy*
Emergence occurs in late afternoon, usually jmst after sundown or as
the sxm. is setting* The period of transformation lasts fifteen to thirty
minutes with the peak about ten minutes after the first subiraago rises.
As the subimago lifts itself from the stream, it can be seen as a slowly
moving grayish body rising upward. If a tree or bush is encountered, the
insect stops, if not, flight is continued upward until the mayfly is lost
to sight and then, when sufficiently high, it probably flies horizontally
to a nearby tree or bush* I have seen the subimagos fly almost straight
up for thirty or forty feet before they were lost to sight. When the inseots
begin to emerge, the area of transformation is easily charted by observing


427
immediately the subimago bursts free of the nymphal exuviae, remains quiet
ly resting on the floating skin for a moment, end then flies away. In a
stream, this is a precarious time, and. the subimago may be swept al ng at
a rather rapid rate. At the slightest disturbance of the floating exuviae,
the subimago immediately take6 to the wing.
In the laboratory, the subimago molts after eight to ten hours, but the
period is somewhat variable. The length of adult life has been determined
only for the female; she has been found to live about forty hours.
The mating flight of Pseudocloeon has never been described, and it
has not been observed for any of the Florida species*
D"vRIVATIfU OF THE SPECIES: Pseudocloeon alach.ua is obviously derived from
_P. parvulum or some closely related ancestral stock. The hypothesis of
insular isolation as an evolutionary faotor,given in the discussion of
the origin of Baetis spiethi,might also apply to Pseudocloeon alachua.
An alternative suggestion may be offered if we but assume that a
mutation,or mutations, occurred to physiologically isolate alachua from
parvulum which in Florida occupies the precise range of alachua, and
if this mutation is of fairly recent occurrence, then this may possibly ex
plain the relatively small range of the species. It is rather puzzling
that P. alachua is entirely absent from the western part of the state,
since condition there, as far as streams are concerned, are apparently
more propitious for stream inhabiting mayflies than elsewhere in the
region. To answer this latter question, reference to a soil map will show
that a broad are of flatwoods and sandy ridges separates the Madison and
Taylor county streams from the streams of Leon, Jefferson, and Wakulla
counties. However, since other species manage to pass beyond this barrier,


165
Ephemera simulans Talker ?
TAXONOMY Approximately sixty nymphs of a species of Ep! omera were
oollected by Professor J* S. Rogers from Kingsley Lake in May, 1935j
subsequent efforts to obtain additional material have been unsuccess
ful# Some of the nymphs sent to Dr. H* T. Spleth were tentatively iden
tified by him as Ephemera simulare Walker Until Florida males are known,
this identification must stand, but it is quite likely that an undesoribed
species is represented.
DISTRIBUTION* No species of Ephemera has previously been recorded from
the Coastal Plain or even the Piedmont (there is a single record of Ephem
era sp. taken in an airplane towing at Tallulah, Louisanna at a height of
two thousand feet)j however, the genus is rather common in the Appalachians,
where the species mostly inhabit streams. E. simulans is known from
Ontario, several of the northwestern states, the midwest, and throughout
the northeastern United States. The furtherest south it has been recorded
is Ohio and Illinois. Traver states that the species is usually found in
lakes and the larger rivers, (see 3)-
ECOLOGY* Although little is known of the ecology of the Florida Ephemera,
there has been much published concerning E* simulans as it occurs else
where in North America. Needham (1920* 283) summarized as follows* "The
mackerels are lacustrine rather them fluviatile in habitat, especially
S. simulans." The Florida nymphs were taken in an Ekmann dredge from
the lake bottom, but whether from sand or silt is uncertain. It has been
said that the nymphs are burrowers in the silt, but judging from the
habits of the related Hexagenia limnophila in Kingsley Lake, I believe
that E. simulans probably inhabits the more sandy areas of the bottom.


22
The alteration of the alimentary tract to suit it for its aerostatic
functions is a character common to all mayflies, and it is one which in
dicates a specialization throughout the order# The modification of the
raouthparts, the tremendous development of the ovaries, the enlargement and
emptying of the alimentary canal, the enormous development of the eyes of
the males, the elongation of the fore legs of the males, and the develop
ment of elaborate oopulatory organs all fit the adult mayfly for efficient
mating and the certitude of continuing the species#
THE FAMILIES OF MAYFLIES
There have been many arrangements of mayflies in various families
and much buffeting back and forth of the genera# As yet, there 6 no
general agreement as to what constitutes a family and what constitutes a
subfamily in the Ephemeroptera# For the sake of uniformity, I shall follow
the taxonomic system set forth by Needham, Traver, and Hsu (1955) in which
three families of mayflies are recognised to occur in North America, north
of Mexico#
Family Ephemeridae^
Subfamily Ephoronlnae
" Ephemerinae*
n Potamanthinae
" Gampsurinae*
" ~> Neoephemerinae*
Family Heptageniidae
Subfamily Heptageniinae*
1# An asterisk after the subfamily name Indioates that representatives are
found in Florida#


BIOGRAPHICAL SKETCH
Lewis Berner was born in Savannah, Georgia on September 30, 1915#
He was graduated from Ida M# Fisher High Sohool, Miami Beach, in June,
1933# Undergraduate work was taken at the University of Florida# In
June, 1937, he was awarded the degree. Bachelor of Science with honors*
Graduate studies were begun in September,1937, and he received
the Master of Soienoe degree in biology in February, 1939# From February,
1939 to June 1941, graduate work was continued leading toward the degree
of Dootor of Philosophy in biology#
Sinoe 1934, he has been employed by the Biology Department of the
University of Florida# From 1936 through 1939, he was a laboratory
assistant, and from 1937-1941, he taught in the General College course,
"Man and the Biological World."
He is a member of Alpha Epsilon Delta, Phi Sigma Biological Society,
and Phi Kappa Phi#


293
the under side) are Corydalis cornuta larvae, caddisfly larvae, sometimes
cranefly larvae, and various other dipterous larvae as well as snails
In the eel grass are Baetis spinosus, B inberoalaris, Pseudocloeon par-
vulun, P punctiventris, Gentroptilium vlridooularis, £ hobbsl, Stenonema
smithae, S* exiguum, and _S* proximum among the mayflies, together with the
snail Goniobasls, one of the most numerous and characteristic animals of
the basio streams in Florida Many other animals are also found in this
eel-grass association
The usual associates in the roots of terrestrial plants projecting
into the water are listed under the discussion of Ephemeralla apalachicola
The ooinhabitants of the underside of boards are Stenonema proximum, £
exiguum, and _S smithae along with many Goniobaeis
I have never found nymphs in very small permanent streams but they
do live in those whioh are one to two feet deep and at least ten feet in
width. The limiting factors involved in stream sise are unknown, but
they may be tied up with the relative rate of flow and the type of vege
tation present (Vallisneria is seldom present in very shallow streams,
and in them detrituB and silt may be too muoh subject to drying at low
water for the nymphs to withstand such great ohanges)
The adults are quite sensitive to drying and must remain in a very
moist situation A large number of subimagos were attracted to my light
one evening I treated these as I would most other species of mayflies,
plaoing them in a paper b&g to await their ultimate moltj however, after
a few hours every individual was dead and beginning to shrivel not
one had shed Many adults have emerged in the laboratory but, here too,
none have imaginated


344
7, 1940, C. L. Goodnight, adults); 3 miles west of Royal Palm State Park
(August 27, 1937, F. t. Y. and L. B,, nymphs and adults)* Gilchrist Co.
Suwaimee river (April 5, 1938, L. B*, adult). Glades Co. Moor Haven
(H H. H. and L. B., nymphs). Highlands Co# Child's Crossing (August 11,
1938, T. H. Hubbell and J. J. Friauf, adults); Highlands Hammock State Prk
(May 13, 1939, F. IT* Y*, nymphs). Hendry Co, Clewiston (February 1, 1941,
M. bright, adults), Hillsborough Co. Tampa (March 21, 1937, S, Gaylord,
nymphs); Little Fish-hawk creek (Maroh 26, 1938, L. B., nymphs); Six-mile
creek (March 26, 1938, L. B., nymphs); 2 miles east of Tampa (March 26,
1938, L. B., nymphs). Jackson Co* Blue Springs Creek (July 1, 1939,
L J. M. and L B., adults; Deoeihber 1, 1939, H* H* II. and L. 3., adults;
June 5, 1940, II* H. II. ar L. B*, adults); Florida Caverns State Park
(December 2, 1939, H. H* II. and L. E., nymphs). Lake Co, St. Johns River
at Crow's Bluff (September 12, 1938, J, R* Preer, adults and nymphs).
Lee Co. Bonita Springs (February 8, 1939, A* F* Carr, nymphs). Levy
Co. 22,3 miles northeast of Cedar Key (April 9, 1937, L. B,, nymphs);
51,7 miles southwest of Gainesville (April 9, 1937, L B*, nymphs); 6 miles
northeast of Cedar Fey (April 9, 1937, L. B,, nymphs); 4 miles south of
Bronson (November 14, 1937, H, H, K,, nymphs), Marion Co* Juniper Springs
("ovember 21, 1937, L* B., nymphs); Withlacooehee river (March 25, 1938,
L, B., nymphs), Munroe Co* -- Pinecrest (July 19, 1935, F. IT. Y,, adults;
August 3, 1937, L. B., nymphs and adults; August 24, 1937, L. B., nymphs
and adults; December 26, 1937, F. H, Y,, adults); Turners River (December
24, 1935, F* N. Y*, nymphs). Palm Beach Co. Lake Worth (February 17,
1941, L. Giovannoli, adults). Polk Co, Polk Lake county line (May 13,
1939, F. II, Y*, nymphs). Putnam Co, Palatka (December 29, 1938, L. B,


20
segments one through five, but Traver (1935) claims that these structures
occur on segments two through six. The latter author stttes that segment
one is almost completely fused with the thorax, a statement with which I
am in agreement. Thus this condition of lessening of number of abdominal
segments, although indicating specialization, is found in a genus which has
many primitive characters.
Specializations are not pronounced in the mouthparts of immature may
flies, but the degeneration evinced by adults is oertainly a highly modified
condition existing in relatively few insects. The mouthparts of the adults
are reduced in size, asymmetrical in form and lack chitirdzaiion. Internally,
the lusoulature degenerates. As a whole they are shrunken very closely
together in a single whitish mass beneath the clypeus. The greatest modi
fications in tlie nymphal mouthparts occur in the burrowing spe oies, where
each mandible gives rise to a long tusk used in digging (fig. 1The
fusion of the parts of the maxillae indicates a specialization in these
structures. Spieth states (1933: 81) that "even the most primitive maxilla
of the mayflies (as is patent from the nature Of the lacinia-galea) is
specialized a3 compared with more generalized insect types."
one of the most interesting specializations undergone by mayflies is
in the enormous development of the eyes of males. In the Baetidae the
compound eyes of the male have become completely divided into two parts,
a lower rounded structure and a much larger "turbinate" portion capping
the smaller part. The oramatidia of the turbinate eyes have become greatly
elongated, and the shape of these eyes is gre tly varied, ranging from a
cap-like, flattened structure closely hugging the lower eye tc one which
extends vertically from the head for some distance. In many species the


226
The genitalia of bradleyl also seem to indicate that the species
occupies a position intermediate between Blasturus end Paraleptophlebia*
The assignment of bradleyi tc Paraleptophlebia has been made on the basis
of the equal length of the three caudal filaments of the adult, this charac
ter having been used to distinguish Paraleptophlebia from Blasturus in which
the median filament is shorter than the laterals. Ide (1935 123) stated
with respect to this characters "Ulmer (1920) remarks *N.B. Diese Gattung
steht heptophlebia so nahe dass sie vielleicht nicbt von ihr getrennt
zu werden braoht.' He is referring to the genus Blasturus, erected by
Eaton to accomodate species of the heptophlebia type in which the median
caudal filament is shortened* Other characters, Eaton found, were not
of generic value, the wing venation being similar to Leptophlebia and
the genitalia of the males very close to the same structures in some of
the species of heptophlebia*" heptophlebia johnsonl, one of the two Worth
American species which Traver refers to this genus, also seams to form
a transition between heptophlebia and Blasturus*
DISTRIBUTION I have found P* bradleyi to be scarce and local in distri
bution in the territory over which I have worked* Its range as at present
known includes north-central Florida, southeast Georgia, and east Alabama.
It seems to be more abundant in the region just south of the Okeefinokee
swamp. The species probably spreads throughout south Georgia, but is
doubtlessly confined to the Coastal Plain* The species has hitherto been
known only from the type series, all other records are my own. (G ECOLOGY: The nymphs prefer slowly flowing streams with silty bottoms and
dwell amid the leaf drift, on submergent vegetation, on sticks, and on
almost any other available support where they may be found in erados or


120
of Paradise (February 12, 1938, 0. VanHyning, nymphs); 1 mile west of
Lake Neuman (May 11, 1937, L* B., nymphs; January 8, 1938, L. B*, nymphs;
Jamaary 25, 1938, L. B., nymphs and adults; August 13, 1938, L. B., adults)|
Roclsy oreek (February 1, 1938, L. B., nymphs); Campus, University of Florida
(March 5, 1938, F* N* Y., nymphs); 5 miles northwest of Gainesville, (Novem
ber 8, 1937, L. B, nymphs)* Bay Co* -- 5*6 miles north of Panama City
(May 30, 1940, H* H. H* and L* B., nymphs); 16*8 miles north of Pnama City
(J ne 8, 1938, H* H* H*, F* N* Y., L* B*, nymphs); 26 miles north of
Panama City (June 8, 1938, H* H* H*, F, N* Y*, L. B., nymphs); 28*7 miles
north of Panama City (June 8, 1938, H* H* H*, F* N* Y*, L* B*, nymphs);
32 miles north of Panama City (June 8, 1938, H* H* H., F. N. Y., L. B*, nymphs).
Calhoun Co* 4*2 miles east of county line (April 7, 1938, H* H, H* and
L. J. M*, nymphs)* Columbia Co. Falling oreek (February 4, 1938, L. B.,
nymphs); 11*5 miles north of Lake City (October 27, 1938, H. H. H. and
F* N, Y*, nymphs)* Escambia Co. Carpenters creek (April 4, 1938, H*
H. H. and L* J* M., nymphs); Flamatin road (April 4, 1938, H* H, H, and
L* J. M*, nymphs); 14*3 miles south of Flomatin (April 5, 1938, H. H* H.
and L. J* M., nymphs); Bayou Marquis (June 1, 1940, H* H. H* and L. B.,
nymphs)* Gadsden Co* 15*1 miles east of Chattahooohee (Aprl 1, 1938,
fi. H* H* and L* J* M., nymphs); River Junction (Maroh 17, 1939, L. B.,
nymphs); 4 l/2 miles south of River Junction (Maroh 17, 1S39, L. B.,
nymphs; June 30, 1939, L. J. M. and L* B*, nymphs and adults; June 6,,
1940, H* H. H* and L. B., adults). Gilchrist Co* Suwannee river at
Oldtown (April 5, 1938, L. B., nymphs). Hamilton Co* *6 miles north of
Live Oak road at Hwy. #41 (February 4, 1938, L* B., nymphs); 8.3 miles
miles south of Jasper (February 4, 1938, L. B., nymphs); White Springs


42
reducing much of the eastern margin of the peninsula to a coastal
archipelago.
5* Persistence of a salt-water barrier between florida and the best
Indies at least since pre-Cenozoic times, and certainly through
out the t>eriod of derivation of the modern biota of the state#
It is unnecessary to hypothesize or theorize that such islands have
existed in order to derive the ephemorid fauna* The winged stage of mayflies
and the methods of dissemination of the insocts would allow for rapid pene
tration of an area should ecological conditions become satisfactory for
the raalntenance of that species* On many of the hahaman islands, conditions
would not allow a very extensive development of mayflies because there
are relatively few or no streams* It is net at all unlikely tuat when
Florida m.3 rising from the sea as isolated islands these islands were
very similar to the Bahamas of today. If such conditions persisted until
land connections were formed, the introduction of mayflies into the region
has been very recent, and, as is hypothesized below, the fauna was derived
mainly through the larger river drainages* Quite lilcBly, there were sane
nayflios inhabiting the Florida islands, but they must have been pond fonos
and species which could withstand wide variations in ecological conditions.
Those species which may be endemic to Florida could oasly have arisen since
the establishment of the peninsula in the Pleistocene*
As Florida rose, the streams draining the southeastern portion of the
continent were extended onto this now area carrying with them their northern
faunae. In the western part of Florida, the Chattahoochee, which drains
the foothills of the Appalachians, and the Flint, which drains the Piedmont
of Georgia, came together to fora the new Apalachicola river* As the


189
Isonyohla perdido ms. name
TAXONOMY: By considering Isonychia perdido to be a new species, I am pro
bably chanoing an enoounter with the usual taxonomic pitfalls. Without
specimens of closely related species for comparison, and with relatively
few adults of the Florida form (two males) this species must remain of
questionable validity until additional information is gathered. In Travers
key to the i^agos of Isonychia, the male adults fall to caption 3 which
reads as follows
"Yenation almost colorlessj fore tibia pale in the middle and
black at each end.... piotipes
Yenation dark; tibia wholly dark .................... 4n
The males of I. perdido, although the venation is almost colorless, do have
wholly dark fore tibiae.
Use of the key to the nymphs leaves one in a hopeless tangle, for the
Florida specimens might fit any one of several species. Traver's use of
the tibial spine of the fore leg as a differentiating character has been
found of absolutely no value in separating species. In every stream from
which nymphs were collected, long-spinned forms and short-spinned have
been found existing side by side, and since this spinning is the only visi
ble difference (except for the number of teeth on the claws, whioh to some
extent parallels the length of the spines on the fore legs), it would seem
that these two groups of immatures are merely variants of one and the same
species. These characters taken as a unit, i. e., relative length of spine
and number of teeth on claws, may be of speoifio value, but until adults
are reared, I prefer to retain these nymphs under a single name.
DISTRIBUTION: I. perdido appears to be limited in distribution to the


149
all at the same height (approximately fifty feet)
Duration of the egg stage has not been determined for H limnophila
Eggs of H* reourvata hatched in the laboratory fourteen days after ovi-
positlon according to Clemens (1922i 78)j Wiebe (1926) found that arti
ficially inseminated eggs hatched in the laboratory in nine days* Spieth
(1938a) hatched eggs of H* ooculta by placing them in jars which were
immersed in a small stream! these took twenty days to develop At the
same time, another group of eggs were kept in the laboratory and these
hatched in only fifteen days*
DERIVATION OF THE SPECIES Since rivers in Florida probably flowed over
the newly emerged land before fresh-water lakes were fomed that were
suitable for burrowing mayfly nymphs, the first Hexagenia species entering
the new region were stream dwellers As habitable lakes began to appear,
chiefly due to the dissolution of underlying limestone, a strain of the
stream Hexagenia may have found conditions ideal in them, and as time
passed this strain became better and better adapted to the lacustrine
existence This new lake form became differentiated into H* limnophila
of today, while H orlando and H. weewa, which may have originated about
the same time, remained as inhabitants of the streams The solution lake
is a type such that H limnophila, beoause of its narrow limits of tolera
tion, has been unable to spread beyond the Central Highlands of Florida
LOCALITY RECORDS: Alachua Co* Santa Fe Lake (April 2, 1935, A. M. Laes-
sle, nymphs) April 7, 1937, L B, nymphs) Clay Co Kingsley Lake
(May 19, 1933, J. S* R, nymphs* April 6, 1934, H. T. Townsend, nymphs;
July 1, 1938, Miss K. V Wheeler, adults; July 2, 1938, L* B, adults;
August 7, 1938, L. B, nymphs; August 10, 1938, Miss E Fullerton, adults;


171
talia of C. inoertus are quite similar to those of £. primus, which is
known only from southernmost Illinois. She considers it to be close
to primus, and apparently even more closely allied to puella, which is
but poorly known. Inoertus probably developed in the Apalachicola drain
age system, and has spread but little, being known elsewhere only from
the Ocmulgee River.
LOCALITY RECORDS* Liberty Co. Bristol (July 29, 1939, Mrs. Long, adults).


2
zations of importance in our efforts to understand our aquatic resources
and to fonward their intelligent use."
One of the most beautifully written descriptions of the life and
mating of these insects is given in poetic prose by ¡Villiam Bertram (1794)
in his "Travels through North and South Carolina, Georgia, Bast and West
Florida", in which he refers to the mayflies seen along the St. Johns river.
Nearly sixty years passed before Ephemeroptera were again noted in the
state, when Francis Walker, in 1853, described the tiny Caenis diminuta
from St. John6 Bluff on the St. Johns river. Not until 1900 was the group
once more reported from Florida; in that year Dr* Nathan Banks described
a new species, Callibaetis florid emus, from south Florida. In 1931 Dr. J.
R. Traver described Ilexagenla weewa and Hexagenia orlando from the state.
"Ureiantnus sp. No. 1" was recorded from Florida by Dr. Traver in 1935, and
in 1937 she gave a full description of the nymph. Four additional speoies
of mayflies were described by myself in 1940, bringing the total list in
the literature to nine speoies. In the present paper thirty-eight addi
tional Florida speoies are discussed, sixteen of which are considered to
be new forms. The descriptions of the new speoies must await future publi
cations.
Only a single paper dealing with the biology of Florida mayflies in
any other than a taxonomic sense has appeared. This paper (Berner, 1941)
describes and discusses ovoviviparity in the mayflies of the genus Calli
baetis, with particular reference to the Florida speoies.
The recent book, "The Biology of Mayflies" by J. G. Needham, J. R.
Traver, and Yin-Chi Hsu, has summarized our knowledge of the mayflies of
North America north of Mexico, and brought it up to date (1935). Naturally,




C. florianus is an ovoviviparous speoies. The female contains
from four hundred-fifty to five hundred-odd eggs which completely fill the
abdomen and occupy a large part of the thorax When the eggs are ready
to hatoh, the young nymphs can be clearly seen They appear &s small,
whitish crvals with fire black spots at one end, and are coiled within the
rery thin, transparent chorion, their legs folded beneath the thorax,
the abdomen bent double so that the legs are concealed, cerci are held
beneath and the antennae close against the head The head is the most
prominent feature of the nymph and on it, fire dark spots, the dereloping
eyes, stand out clearly against the white body* Abdominal segments, mouth
parts, and the rather long legs are clearly discernible when a specimen
is uncoiled. Gills, of course, hare not yet formed and if they behave in
this species as in others in which the post embryonic derelopment has been
studied, these structures will probably derelop in the second or third
instar. (Berner, in press)
The subimago emerges in the late afternoon. On February 21, many sub-
imagos were noted rising from the surfaoe of a sink-hole pond between 3:45
and 4:00 p m Other field observations indicate that emergence occurs about
one to two hours before sunset and rarely afterwards. In the laboratory,
the emergence time is upset at times as evidenced by transformations after
dark and during early morning.
The subimaginal molt takes place about seven to nine hours after the
winged stage is assumed* As adults, females have been kept alive a maxi
mum of thirteen days; in nature, however, the imagina! period is probably
several days shorter. The male dies ?dthin two days after emergence,
aongevity is probably correlated with ovoviviparity in mayflies. Normally


27
TAXONOMIC CHARACTERS
Perhaps taxonomists have not been sufficiently thorough in their
treatment of mayflies* All structures or features that have been used
taxonomically are external; until students of mayflies overcome their
inordinate desire of preserving perfect specimens, the approach study
of internal anatomy will not be used* Of course, the difficulties involved
in an investigation of the internal anatomy of small organisms must also
be taken into consideration, and when large numbers of individuals are to
be examined such studies would obviously be out of the question* Further
more, although it might be thought that taxonomic studies carried on for
so long a time as has been the oase in Ephemeropteran work would have
resulted in a very thorough knowledge of the external morphology of the
insects j however, there are structures which are still imperfectly known,
even though they are used to a great extent in taxonomic work.
Of primary importance in the separation of families, genera, and even
species, the wing veine of mayflies are even now not satisfactorily under
stood from the standpoint of homologies* The problems of venation have
been discussed above in the considerations of phylogeny and venation* The
wing veins of each genuB of mayflies, and in particular the longitudinal
veins, air very constant in struoture and position so much so that only
in few groups can specific differentiation be found, and then only by re
ference to minute details* Eaton (1883-1888} 4), in his monograph, has
clearly summed up this situation "Unstable in minutiae, so closely is the
essential plan of the neuration adhered to by nearly related Mayflies, that
the general facies of the wings is an important aid to their classifica
tion, affording characteristics as easily recognizable as the style of


336
In south Florida, nymphs have also been taken from temporary ponds,
roadside ditches, and from small pools in abandoned rook pits. I strongly
suspeot the species of breeding even in a small, artificial fish pond.
In north Florida, the habitat of C. floridanus is similar to that of
the south Florida form. The nymphs are most common in roadside ditches
where they live among the stems and leaves of submerged vegetation, clinging
to the plants, darting swiftly from one stem or leaf to another, or moving
slowly and graoefully over the surface of the plant. In the roadside ditches
the water is usually shallow, not more than three to four feet deep, choked
with vegetation, and stagnant. The plants most commonly include Pontederia,
Perseoarla, Globifera, Saururus, Isnardla, Webateria, and many algae. Very
seldom are nymphs found in the algae where it forms mats, for their move
ments would be much too restricted by the entangling strands. Normally,
the nymphs can be found where the vasoular plants are densest.
Temporary woods ponds, sink-hole ponds (with an open surface), and
lakes with marginal vegetation usually have many Callibaetis nymphs. Cypress
swamps, marshes of various types, and margins of slowly flowing streams
where there is vegetation suitable for harboring nymphs also maintain their
populations of C. f. minor. The Immaturea cannot withstand a strong flow
of water and I have never taken them from rapidly flowing creeks unless
these streams pooled or had thick growths of shore vegetation which helped
to slow the current in this zone.
Those sink-hole ponds in whioh the surfao9 is covered with duckweed
usually do not have mayfly nymphs. There may be several faotors accounting
for their absenodi the covering of plants makes it impossible for adults
to lay eggs or for nymphs to emergej an absence of submergent vegetation




97
38*
(see fig* 31)
Pseudocloeon parvulum
Length of median caudal filament greater than width of laterals
at base; lateral filaments faintly* or not at all* banded
(see fig* 32). ITo grayish areas on gills*
Pseudocloeon alachua
39 (35*)
Middle tail shorter and weaker than outer ones* Distal segment
'"yj.
of labial palp rounded (see fig* 33); maxillary palp usually
not extending beyond tip of galea-lacinia* Hind wing pads
present*
39
(4.0)
*
Middle tail praotioally as long and stout as outer ones* Distal
segment of labial palp dilated and truncate apically (see fig*
34)* Maxillary palp extending somewhat beyond the tip of the
galea-lacinia (see fig* 35)* Hind wing pads present or absent*
(44)
40 (39)
Seventh gill reddish-brown (see fig* 36)*
Aoentrella ephippiatus
40*
Seventh gill not deeply colored*
(41)
41 (40*)
Seventh pair of gills lanceolate (see fig* 37)*
Baetis epiethi
41*
Seventh pair of gills rounded (see fig* 36)*
(42)
42 (41*)
Second segment of labial palp greatly expanded distally (see fig*
33)*


318
Co. 6*6 miles east of Perry (February 5, 1938, L* B,, adults and nymphs)|
near northern oounty line (February 5, 1938, L# B*, nymphs)* Volusia Co*
Deleon Springs (August 5, 1939, J. R Preer, adults), Washington Co* ~
Holmes Creek (July 2, 1939, L* B*, adults),
Caenls hilaris (Say)
TAXONOMY* Caenis hilaris, one of the earliest described North American
speoies of mayflies, is not only the smallest ephemerid found in Florida
but also one of the smallest known, being surpassed in this respect only
one other member of the same genus* The body and wing measurements are
slightly over two millimeters* The speoies was desoribed as Ephemera
hilaris by Say in 1839; later it was redesoribed from Illinois material
by Walsh (1862*381) after first having been plaoed in the genus Caenis
by Francis Walker (1853* 683)* In 1861 Hagen briefly described the
adults ( pp, 54-66) and Walsh, in his description, pointed out differences
between Hagens specimens and his own* C* hilaris was again redesoribed
in 1871 by Eaton (p* 96) and still again in 1884 (p* 147). After an in
terval of nearly fifty years, MoDunnough revised the descriptions of this
species in 1931 (pp. 265-256), and its most recent treatment is by Traver
(1935* 680) in the taxonomio section of "The Biology of Mayflies, liy
specimens fit MoDunnoughs and Travers descriptions fairly well, and the
few minor differences are probably only individual variations*
DISTRIBUTION* In Florida, C. hilaris is oonfined to an area in the north
western part of the state extending from the western boundaries to some
what east of the Apalaohloola River, The speoies is rather widely distri
buted over the eastern United States but is unknown in Canada and west of


183
Found with Siphlopleoton in the Styx river plant association were
nymphs of Stenonema proximum, Paraleptophlebia bradleyi, Blasturus sp*,
and Callibaetis sp* In the Shoal river a specimen of the rare Oreianthus
sp. No* 1 was found living on the same piling from which the Siphlopleoton
nymph was collected* Baetis spinosus, Blasturus intermedius, Isonychia
perdido, and Stenonema smithae nymphs were taken along with the Siphlopleo
ton nymph from Sandy creek*
SEASONS* All specimens of S* speciosua in my collection were taken in
December and range in size from less than one-third grown to penultimate
instar* This would seem to indicate a winter, spring, and probably summer
emergence* I have little doubt but that emergence is year round, since
almost mature nymphs were collected as late in the year as December. It
so happened that at the time these nymphs were collected the temperature
ms near freezing* The nymphal metabolism is most likely slowed during
a cold snap, but as soon as the temperature rises growth is resumed and
emergence ensues. There is a direct correlation between temperature and
emergence; if there is a prolonged period of warmth during the winter,
there may be a fairly large number of adults emerging* Of course, as far
as this species is concerned, this is entirely hypothetical since my state
ments are based on observations of other species which also have a high
ecological valence* Travers adult specimens from Georgia were collected
April 14-17.
HABITS Very little has been written of the habits of Siphlopleoton.
Traver says of the North Carolina species (1932 95) "Very similar in
habits and habitat to Slphlonurus. Often, like the former, found among
aquatic plants or trash near the shore, where there is a slight but constant




319
Oklahoma* It inhabits a wide variety of physiographio provinces, rang
ing from the Coastal Plain into the Appalachian Province. The Florida
reoords bring hi laris much farther south than it was previously known. (See **//-*).
ECOLOGY* Nymphs have been taken only from gently flowing streams. These
streams are predominantly of the sand-bottom type with debris accumulated
near the shore. The habitats of the nymphs are identical with those of
Ephemeralla apalaohioola, as described for Sweetwater Creek. In other
streams, nymphs have been found in the vegetation near shore, among leaf
drift, and on submerged logs, stioks, etc. I have never collected any
specimens from the deeper, swifter parts of the streams, even where debris
was present. Adults have been taken only at Blue Springs Creek near
Marianna. Nymphs have not been found at this locality, and it is uncertain
whether they inhabit the stream itself or the lake formed by a dam. The
stream would be a rather exceptional habitat for the speoies, since it is
decidedly basic, without vegetation, with a very soft bottom, and has
an abundance of snails*
C. hjlaris nymphs are commonly found with the same mayfly species
s those associated with Ephomere11a apalaohioola.
SEASONS* Because of the distance I have been unable to make the trips to
northwest Florida which would have permitted obtaining fuller data on
the seasonal distribution of £# hilaris. However, some evidence is at hand
which leads me to believe that, like diminuta, C. hilaris emerges through
out the year. In my collection there are adults taken in June and July,
and last instar nymphs during November and December. Although these re
cords leave many gaps, it would seem logioal from a study of younger
specimens to aBsume that emergence must occur during warm periods of the


IS
tails are almost bare.
PRIMITIVE AND SPECIALIZED CHARACTERS
It is frequently said that mayflies are primitive insects, and it
is certainly true that many primitive characteristics are exhibited by
this order. Luring the Carboniferous period, or probably earlier, a group
of winged insects evolved a mechanism in the wing base for flexing the
wings horizontally over the back when not in use. The descendants of
this group (Neopterygota) include the majority of modern winged inseots,
while the more primitive nonwing-flexing inseots are represented today by
only two orders (Odonata and Ephemerida), both of which have descended
from Carboniferous times but are not closely related to each other. (Snod
grass, 1935 12). The earliest known fossil insects identifiable as may
flies were taken from Permian shales. These early mayflies were long-winged,
long-bodied inseots with slender lege and three long tails. The fore and
hind wings were of nearly equal size and the wing veins were very well
developed. Fossil mayfly nymphs taken from Jurassic beds in Siberia
seem to have gills on nine abdominal segments.
The fore wings of the more generalized mayflies possess nearly all
the veins of the archetype venation. The costal vein is rather short,
running only as far as the humeral brace, and from thenoe outwards to the
edge of the wingj the fore margin consists of a slightly thickened, folded
wing membrane beyond the costa. The suboosta extends from the wing base
to the apex of the wing, while the radius branohes a short distance from
the wing base to give rise to R^, which runs parallel to the subcosta, and
to the radial sector, which in turn divides. The radial seotor forms Rg


91
from the plates (see fig. 14).
(15)
It iills filamentous; each gill on abdominal segaents 2-7 consists
of two clusters of slander filaments (see fig, 13),
Flabrophlebia vibrans
imiiwm I >! !!! ir i r ~ ~ r i
IS (15) Sills on abdominal segment 1 single, unbranched; terminal
extension of upper gill plate of each middle pair rather broad
and spatulate (see fig. 14).
Choroterpes hubbelli
16* Gills on abdominal segment 1 definitely bifid except at basei
terminal extension of each gill on. middle segments very slender
(see figs. 11 and 12).
Blasturus intermedins
17 (14*) Spine or ninth abdominal segment not more than l/i the length of
that segment; spinules on posterior margins of torgites 1-10.
Labrum only shallowly indented on fore border (see figs 15 and
16).
Paraleptophlebia (18)
17 Spine of ninth sognent long and slonder, l/2 as long as length
of that segment; spinules on posterior margins of torgites 6-10
only. Labrum rather deeply indented on fore margin (see fig 16).
Habrophlebiodos brunnelpennis
13 (17) First gill narrow, tracheae without lateral branches; gills 2-7
broad, lobes separate to base, tracheae with lateral branches
(see fig 17). Dorsum brownish with four yellowish streaks at
at anterior border of eaoh tergite*


342
the life span of adults is from a few hours to two to three days, but a
female Cloeon dipterum, the European ovoviparous mayfly, was kept alive
for twenty-one days* (Berner, in press) Probably after mating, the female
becomes quiescent until the eggs are ready to hatch* TShen the time arrives,
the female takes to the wing, flies to a body of somewhat stagnant water,
and releases the eggs which probably hatch at the moment of laying*
Before the discovery of ovoviviparity in C* floridanus, I secured eggs
from a female which I was reasonably certain had mated, placed them in a
dish of water, and observed them daily until decomposition set in* Nor
mally mayfly eggs when place in water will form a protective jelly-like
layer around themselves, or release attaching stringsj however, in floridanus
this was not the case* Also, I tried artificial fertilization of eggs,
and as before, they decomposed*
I have not observed the mating flight of this species, although I have
found as many as ninety females among the vegetation in a small area at
the same time* Large groups of females have also been seen at lights and
the observations of large numbers pf females wore reported to me*
DERIVATION OF THE SPECIE!! C* _f. floridanus is endemic to south Florida
and is derived from the same stock which gave rise to C* f* minor* It is
conceivable that the parent stock of Callibaetls floridanus became isolated
on the Ocala or pliocene islands. As Florida rose, migration into the
Peninsular area occurred and the southern form evolved* Possibly at the
same time, the original stock on the Coala island,or on later islands, began
to change and produced the C* f* minor of the present; the species moved
outwards, but did not enter south Florida*
LOCALITY RECQRLBj Alachua Co* Gainesville (October 24, 1937, L* !>*,


124
identifiable as S* smithae, and this further leads me to believe that
exiguum is the only representative of the pulchellum complex in this
southern area*
The distribution of exiguum is rather interesting because the species
is known from three physiographic provinces Coastal Plain, Piedmont, and
Valley and Ridge* In which of these it predominates, there is no way of
knowing at present, but the speoies is certainly well distributed in the
first mentioned region* (5ee ^
ECOLOGY* Ecologically, the speoies is very similar to S* smithae except
in two respects# In west-central and north-central Florida, nymphs are
very seldom found in smaller streams, but are very numerous, probably out
numbering smithae, in the larger creeks and rivers* The situations within
the streams that are inhabited are, however, identical with those of smithae.
Secondly, a single nymph has been collected from a sand-bottom lake, an
habitat in which smithae has never been found* This specimen was brought
from a depth of fifteen feet by means of an Ekmann dredge, but it was dead
when oolleoted* However, it was in a very good state of preservation and
death must have occurred either Just before colledtion during collection
because of an injury suffered in the dredge, although there were no external
manifestations of suoh injury* It is surprising that only a single nymph
should have been oolleoted, for I examined the shore materials rather
thoroughly, the airea in which the nymphs would be expected to be found*
There is a small, slowly flowing stream entering the lake at one side and
it is barely possible that the nymph was washed in from here shortly after
death,
SEASONS* Seasonal emergence is identical with that of S* smithae, that is.


400
nymphs are found clinging to the vegetation, principally Hals. They never
venture into the swifter waters where C* hobbsi is found* The positions
of these two species of Centroptilum in the Santa Fe river affords one of
the best examples for the idea that claw size is directly related to habitat,
for the claws of C* viridooularis are thin and antennuated, three-fourths
as long as the tarsi, while the olaws of £* hobbsi are shorter and thicker,
about one-half as long as the tarsi*
The habits of the species in other streams in Florida are very much
like those just described, but in none has the species been found to be as
abundant as in the email stream near Gainesville*
The streams inhabited by C* viridooularis nymphs may be either acidic
or basic, but not strongly inolined in either direction. Hatchet creek is
an excellent example of a swamp stream in which the water is heavily tinted
with organic aoidsj at times, the coloration is so Intense that the water
takes on the appearance of strong tea* fin the other hand, the Santa Fe
river, fed by springs, is normally colorless and slightly basic in reaction.
Although the species is quite tolerant of very slowly flowing water, it does
not inhabit ponds and other standing bodies of water. The nymphs have been
oolleoted from places in Hatchet creek where there was no preceptible current,
yet in the standing water of the lboratory the nymphs could live only a few
days.
Associated with £ viridooularis in Hatohet oreek are a number of
species of mayflies Baetis spinosus, B. spiethi, Aoentrella ephippiatus,
Pseudooloeon alaohua, Callibaetis floridanus minor, Caenis diminuta, Blas-
turus intermedius, Choroterpes hubbelli, Ephemerella trllineata, Para-
leptophlebia volitans, P. bradleyi, Stenonema smithae, and £ proximum.


101
are separated by gill structure.
Spieth suggests that Stenonema (Eodyonurus) displays two lines of
development; one is represented by the interpunctatum group, the other
by the tripunotatum-pulohellum complex. lie also suggests that the in
terpunctatum speoies are more closely related to Heptagenia than is the
latter complex of species, a conclusion with which I certainly agree, for
when the genitalia of the two groups are examined, there is a great deal
of parallelism seen to exist between them. Stenonema is a rather unspeoializ-
ed genus which is not highly modified from the ancestral type, although
it may be fairly high on its particular phylogenetic branch.
Stenonema is one of the largest genera of mayflies in North America.
Ko species are known from western North America, and here heptagenia,
.Rithrogena, etc. become the predominant forms. The Appalachian province
is the ideal region for the development of Stenonema, ana in this area
there are many species occupying almost all available situations* Although
other Heptagenine mayflies occur in the mountains, Stenonema is the one
most frequently found. Only a very small proportion of the species of
Stenonema are known to occupy the Coastal 'lain although from their evident
success in Florida, I would suspect that when various other parts of the
province are examined, other species will be found to be just as success
ful.
Stenonema smithae Traver
TAXONOMY* Stenonema smithae is the most recently described speoies of
the genus. During a short collecting trip through several states in
the southeast, Traver discovered S. smithae in west-oentral Alabama near


73
ACKNOWLEDGEMENTS
I wish to express ray sincere appreciation to the many people who
have helped in one way or another in this study# In particular, I would
like to thank Professor T. H. Hubbell for continual encouragement in this
work, for many helpful criticisms, and for examination of the manuscript*
Professor J* S* Rogers whose aid, encouragement, and advice have been
invaluable| Dr* H* H* Hobbs for numerous suggestions and discussions of
the problem, for aid in collecting, and help in drawing* Various other
members of the faculty of the Department of Biology of the University of
Florida have also offered many suggestions and participated in discussions
which have been very elucidating* I would like to extend my thanks to
Professors C* F* Byers, H* B* Sherman, W# J* K* Harkness, Drs* H* K* Wallace,
and A* F* Carr* In addition, I wish to acknowledge the helpful suggestions,
oritioisms, and disoussionB of my fellow graduate students at the University
of Florida*
To the many friends who have collected mayflies for me, I take this
means of expressing my gratitude* In the locality reoords of each species,
the collector's name is placed in parentheses. In particular, Mr* F* N.
Young, Mr* L* J* Marchand, and Mr* W. M, McLane have assiduously collected
all ephemerids with which by chanoe or otherwise they have happened to
come in contact* Those persons who have collected numerous specimens have
been referred to by initial only, as follows)
J* S# R* J* Speed Rogers
H* H* H* H. H* Hobbs
L* J* M* L* J* Marchand
F. N. Y. F* N. Young
L. B*
L* Berner


404
Wins pads blackened * 3/13/40
Died without emerging **. 8/13/40
The mating flight of no North American species of the genus has been
described, nor has it been observed for the Florida species* However,
I did note a single female flying over mid-stream about six to ten inches
above the water; apparently it was ovipositing. This took place in Octo
ber at about 5:46 p. m., just as the sun was setting*
DERIVATION OF THE SPECIES: The distribution of C* viridooularis outlined
in the section on geographic distribution indicates that the genus obvious
ly must oocur somewhere else in the Coastal Plain, or at least in the
Piedmont, and further collecting will, without doubt, show this surmise
to be oorreot. Probably the species is derived from an Appalachian stook
and entered Florida through the Apalachicola river drainage system, spreading
into the Suwannee drainage as the species moved south* From these rivers,
serving as highways, the species has dispersed over Florida until it now
occupies one of the widest ranges of any Florida species*
It does not seem likely that the species is a relict, isolated on
the Floridian islands of the Pliocene or Pleistocene, because all related
speoies appear to be confined to the northern part of the United States*
LOCALITY RECORDS: Alachua Co* Hatchet Creek (May 11, 1937, L* B, nymphs;
July 6, 1938, M* H* Carr, nymphs from fish stcanaohs; July 9, 1938, L* B.,
adults; April 1, 1939, L, B,, adults; April 13, 1939, L. B., adults; April
27, 1939, L. B*, nymphs; May 6, 1939, L* B,, adults; June 24, 1939, L. B.,
adults; August 10, 1940, L* B*, nymphs); 1 mile west of Lake Newnan (August
13, 1938, L. B., nymphs); Hogtown creek (October 13, 1940, G* Pournelle,
nymphs); Santa Fe river at Poe Springs (May 21, 1934, J* S. R., nymphs;


179
DERIVATION OF THE SPECIES Both of the North American species of Crean
thus are restricted to the southeastern United States, "which probably
represents their center of origin. This idea is borne out by the fact
that "Oreianthus so. No. 1", in Florida, has a very restricted seasonal
range (see page for hypothesis). Present distribution seems to in
dicate that "Oreianthus sp. No. 1" arose in the Apalachicola river and
this origin appears to have been fairly reoent, for even though the
species is tolerant, it has spread very little beyond the drainage of the
major stream*
LOCALITY RECORDS* Gadsden Co. 4 1/2 miles south of River Junction
(March 17, 1939, J. S. R*, h. H. H., F. N. Y., L. B*, nymphs). Liberty
Co. 10 miles south of River Junction (March 17, 1939, J. S. R., H. H* H.,
F. N. Y., L. B., nymphs)j Sweetwater Creek (November 4, 1938, J. S. R.,
T. H. Hubbell, H. K. Wallace, C. J. Coin, L. B., nymphsj December 1, 1939,
H. H H., W. M. MoLane, L. B., nymphs). Okaloosa Co* Shoal River
(December 11, 1937 H. H. H., F. N* Y*, L. B, nymphs).


es
the sand-bottom lakes form the most conspicuous bodies of water in the
central highlands. There are literally thousands of these lakes in this
region and they are particularly numerous in Late oounty. The lates vary
in size from a quarter of a mile to nine or ten miles in width, but the
depth is not correspondingly great and most of them are sliallow, not more
than forty or forty-five feet at their deepest holes. There is little
vegetation except at the margin, and this is chiefly Saocrolepis striata,
Utrioularia, and algae. Wave action is slight but it is probably suffi
cient to prevent the growth of more usual aquatic vegetation along the
sandy shore. The dacorolepis extends out into the lates to a depth of five
or six feet and beyond this zone vegetation is limited to submergent plants
such as Utrioularia, which lies on the sand bottom as far out as there is
sufficient light penetration for normal photosynthetio processes to take
place* In this region, some silt is intermingled with the sand, but much
of the sand is bare, beyond a depth of about twenty feet, silt accumulates
and covers the bottom sand with a layer several inches deep; with increase
in the depth of the lake there is a direct increase in the amount of silt.
In the very deep parts of the lakes, the silt may reach a depth of a foot
or more, and in this region it is a very thick, black, fine, and oozy mud
in which almost no organisms live# Along the shore some debris colleots,
but is not abundant; this debris forms an habitat for many insects which
are normally found in streams. Probably the wave action in this region is
sufficient to oxygenate the water and produce conditions whioh simulate
those of moderately flowing streams. The water of the lates varies from
very clear to strongly tea colored and the turbidity is also very variable
according to the late. Most of the lates are oircum-neutral, ranging not


294
HABITS: Examination of the guts of nymphs showed that those specimens
which ere root inhabitants feed on epidermis of dead leaves, other debris,
and occasionally on diatoms; the nymphs living among water grasses
feed on the epidermis of these plants as well as on the diatoms covering
them, although the latter are not eaten in great numbers. The moss-dwell
ing individuals also feed to a large extent on plant epidermis, but the
diatoms form a more important element in their diet than in that of the
two other groups*
The nymphs are rather awkward swimmers, using an undulating action
of the abdomen for propulsion* The tails bear only a few long hairs which
could not possibly aid the nymphs in swimming# The nymphs seldom swim and
move about almost entirely by crawling* The operoulate gills are more or
less rhythmioally raised to allow aeration of the lower or posterior pairs.
In the lowered position, the operoulate gills cover rather completely all
others behind them, but not so well as do those of Ephemeralla trilineata*
SEASONS: Prom a study of the material in my collection, it would appear
that Trioorythodes albilineatus is a year-round emerger* For that portion
of the state east and south of Leon County, I have records of adults taken
during early February, March, April, June, August and October; however,
my reoords of adults from west Florida do not indicate such a disregard
for season. In that region adults are known only for April May, and
June, with mature nymphs reoorded during July. Returning to a consideration
of nymphs, west Florida records of the immatures may belie adult oolleo-
tions, for very young nymphs have been taken in May, June, July, and Nov
ember. If the life cycle of the speoies is comparable to that of Caenis,
then adults would emerge each month of the year. If, on the other hand.


221
The following is an excerpt from my notes of May 6, 1939 "Collected
at Hatchet Creek. Specimens of P. volitans taken from bridge about 5:15
p. m. were relatively insensitive one subimago out of reach was stimulat
ed by touching it gently with my netj however, it did nothing more than
take one or two steps, until violently pushed, when it then flew out of
reach of the net. About 6:45-7:00 p. m* I again attempted to capture some
specimens from the bridge but at the slightest sign of movement on my part,
the mayflies would immediately take wing. Only two were lethargic enough
to allow me to capture them." From this, it would seem that P. volitans
adults are much more sensitive just after sundown.
LIFE HISTORY: Little work has been done on the life history of Paralep-
tophlebia, except for the descriptions of last instar tymphs for taxonomic
reasons. A brief discussion of the external features of the eggs of five
species of this genus with a figure of the egg has been given by Smith
(in "The Biology of Mayflies"), and a sentence and figure were devoted to
the genua by Morgan (1913:399).
From Ides data on the emergence of P# volitans in Canada, it is
obvious that the life history in that region occupies an entire year. I
strongly doubt that the same length of time is required in Florida. Several
attempts to hatch eggs have been unsuccessful, perhaps because the females
from which the eggs were taken may not have mated. Emergence records and
rate of growth of nymphs in the laboratory indicate that six to eight months
may be sufficient for nymphal development.
Emergence* as observed outdoors, occurs normally in late afternoon,
about txvo hours before sunset. In the laboratory, most subimagos appeared
at about the same hour, but in seme instanoes individuals have transformed


seo
BAETIS Leach
Baetls is one of the first known mayfly genera, haring been described
by Leaoh in 1815. Westwood described Brachyphlebia in 1820, but this prov
ed to be synonymous -pith Baetis, and again in 1843 a portion of Daetis
was sjcaonymized by Pictet* The genus Aoenfcrelia was split off in 1912
by Bengtsson and since has caused much dissension among taxonomic Ephemerop-
terists. Many species of mayflies were described under the genus Baetis
before this all inclusive category was divided into several smaller genera*
At the time of publication of "The Biology of Mayflies, there were forty-
one species of Baetis listed frcm North .America north of Mexico, and since
that date (1935) there have been five additional species described in the
genusi 5* foemina McP, jB jesmondensis McD*, B* persecuta McD., 3* maodun-
noughi Ide, all frcm Canada,and B splethi Berner from Florida* The re-
erection of Acentrella (Traver, 1937) removed six of the speoies from Baetis,
thus reduoing the number known at present to forty* Of this group, Acentrella
plus Baetis, twenty-three have been described by McBunnough, eight by Traver,
seven by Dodds, and the remainder by other workers*
The treatment of Baetis as given by Traver (1935) was severely cri
ticized by McDunnough (1938), but the sections of the genus treated by
him. are all western and northern and are quite distinct from the Florida
species, therefore, his criticisms need not be discussed here*
Traver divides the genus into two main groups on the basis of genitalia,
the moffati type and the intercalaris type* Each of these is then subdivided,
the former including the modified moffati type, the splnosus type, and the
true moffati types the latter includes the true intercalaris type and the


161
no definite evidence to support this statement, but nymphal growth rate
seems to point to such a conclusion*
Some indication of the rate of growth under rigorous conditions is
shown by the following figures based on laboratory-reared nymphs from
Hogtown oreek. An attempt was made to rear nymphs in the stream as a cheok,
but due to the contamination mentioned above, this failed
Date measured
Feb. 2
May 1
June 19
No. of speci
mens measured
32
31
19
Smallest nymph
6.5 mm.
9.5 mm*
9.0 mm.
Largest nymph
2 5 mm.
23 mm.
22 mm.
Average size
13.6 mm.
16*3 mm.
17*5 mm.
The male nymphs, just before transformation, ranged from 17.5-19 mm.
in length. The larger nymphs were females.
Emergence in the laboratory occurs in late afternoon, and the sub-
imaginal molt takes place from fifteen to twenty hours later.
I have not observed the mating flight of H. orlando, nor has it been
described; I believe, however, that it would be identical with that of
H* weewa.
DERIVATION OF THE SPECIES* If orlando is a distinct speoies, it was un
doubtedly derived from the same stook which gave rise to weewa, and it
originated in the waters of northwest Florida, in southwestern Georgia,
or in Alabama. Thence, it spread eastwards and southwards in Florida.
LOCALITY RECORDS* Alachua Co. Hogtown oreek, 1 mile west of Gainesville
(January 17, 1940, L. B., nymphs, adults reared June 9 and 10); Santa Fe


largement of the St. Johns river not far frcm its headwaters. I have
been unable to visit this lake and have no specimens from it; however,
circumstantial evidence leads me to believe that the Hexagenla occurring
in Lake Harney must certainly be the species here named limnophila. (.See mar
ECOLOGY H. limnophila is one of the most ecologically limited species
found in Florida. The nymphs burrow in the sand and silt of the lake
bottoms. The only way in which the nymphs have ever been taken has been
through the use of an Ekmann dredge, for they burrow in fairly deep water
ranging from nine to thirty feet in depth. The greater concentration of
the immatures apparently lies in the region from eighteen to thirty feet,
but a few nymphs have been collected from the deepest parts of most of
the lakes which were sampled. One exceptional specimen was even taken
at a depth of forty-five feet, the deepest spot that could be located in
Kingsley Lake. There was some evidence of thermal stratification in the
deeper parts of this lake during August, and no nymphs could be found
below this zone; however, immatures were taken closer to shore. That
part of the lake bottom in which Hexagenla nymphs are most common is
sandy but usually overlain with a very thin layer of silt and has Utri-
oularia scattered over it. In the deeper portions of some of the shallow,
sand-bottom lakes, there is a deposit of rather slimy, but firm, black
mud covering the sand bottom. Nymphs are frequently collected from this
inud, and along with them there may be brought up many Corethra larvae,
a few annelids, and an occasional amphipod (Euorangonyx graoills Smith).
Although the large lakes such as Newnans and Orange are very inter
esting in themselves, from the standpoint of ephemerid speoies present
they do not rank very highly because burrowing mayflies are completely


202
BLASTURUS Eaton
The genus BlasturuB was desoribed by Eaton in 1881 and redefined in
his monograph on the Ephemeridae in 1884* In 1932, Traver discussed the
genus as it occurs in North Carolina and desoribed five new species* In
her paper, she included the description of "Blasturus11 gracilis, but
subsequently removed this species to the genus Leptophlebia, after first
shifting all the North American species fomerly plaoed in that genus to
Paraleptophlebia* Ide (1935t 124) suggested that Leptophlebia johnsonl
might be intermediate between "Blasturus" and other Leptophlebia species,
and that it would be well to drop entirely the generic name Blasturus*
Spieth (1938* 214) followed Ide's suggestion, and in his discussion of
coloration in relation to seasonal emergence uBed the generic name Lepto
phlebia to refer to species plaoed in Blasturus and Paraleptophlebia by
Traver*
"Both as to nymphs and imagos, the genus Blasturus is a difficult
one to separate into its component species* Structural differences are
minor and difficult to recognize until some time is spent in studying the
group as a whole* Color differences exist, but are likewise minor and
relative, and are an unsatisfactory basis for the separation of species."
So wrote Traver (1932j 123), and, to date, the situation has not changed*
Even though there may be some justification for synonymizing Blasturus,
I am retaining the name for the Florida species, sinoe it does serve as
a convenient oategory, and is useful in presenting a picture of the Lepto-
phlebines of Florida. This action is, furthermore, apparently in line with
Spieth's most recent views (l940aj 325)*
The genus (or subgenus) Blasturus is entirely Nearctio, and is generally




in Alabama as collections have been made*
103
Tuscaloosa is located just beyond the Fall Line on the Coastal Plain
All the Florida records are, of course, Coastal Plain. It therefore appears
that the species is confined to this physiographic province, although it
may pass beyond this barrier and into the Piedmont* It seems rather
doubtful that streams as close to the Piedmont as those at Tuscaloosa
should have the species while those just on the other side of the Fall
Line should not* Hinged insects such as mayflies could easily surmount
such an obstacle and enter the streams in the Piedmont, at least in the
lower region Probably, S smlthae is distributed widely over the Coastal
Flain wherever there are permanently flowing streams, but until much more
collecting is carried out, this must remain hypothetical* (fee
LCOLOGJY; Almost any constantly flowing brooklet, creek, or river will
have nymphs of b smlthae in it# These insects can be found on various
submerged objects which are at least partially anchored in the stream bed,
including submerged logs, sticks, leaves, rocks, pebbles, and even tin
cans* In the sand bottom creeks where there are broad expanses of almost
barren sands, of course, no nymphs are found but if there is, by chance,
a log in mid-stream, the underside is almost certain to have these nymphs
on it. A board partially briried in the sand where the ourrent slackens
may produce as many as fifteen to twenty nymphs, the majority being rather
young. Stones, likewise, will support a fair number on the darkened, pro
tected undersurfaces* iiany immatures can also be found among leaf drift
which accumulates in the more slowly flowing water or becomes entangled
in submerged branches and vegetation* Frequently, but in no wise as com
monly as on more solid supports, nymphs occur on vegetationj however, the


266
EPHEMERELLA Walsh
"Although the mayflies of the present time are the isolated remnants
of a vanishing race of insects...... a few genera appear to be flourishing
in our own time, if the great number of closely similar speoies is to be
taken as evidence. In the great Ephemeralla complex species-making is
perhaps still going on." (Needham, Traver, Hsu. 1935, p. 209). By 1939,
sixty-nine speoies of this genus had been listed for North America alone,
and with the discovery of four additional species from Florida the number
is now brought to seventy-three.
MoDunnough (1931bi 188) stated that Chitonophora could not be separated
from the genus Ephemerella, and he divided the genus into four sections.
Traver (l934i 206) used MoDunnoughs divisions of the genus with only
slight modifications, but in 1935 she divided Ephemerella into seven groups,
which were retained in her 1937 treatment of the genus. MoDunnough (1939:
50) apparently did not agree with Traver*s conception of the groups, for
in describing E. jacobi he says "Evidently belongs in a group with hetero-
oaudata MoD. and hystrix Trav." According to Travers classification
heterocaudata belongs in the serrata group while hystrix is placed in the
needhami group.
From the nymphal standpoint, Traver*s needhami and invarla groups are
rather poorly defined. MoDunnough obviates this difficulty by placing three
of the speoies of the needhami group in his section 1 whioh inoludes the
speoies of the invaria group. This was done in 1931 before angustata,
oatawba, cono innata, euterpe, hystrix, and maoulata were described; all
of these have been included in Traver*s needhami group. In her 1937 paper,


257
Baetisca rogersi Berner
TAXONOMY-: Baetisca rogersi, the most reoenbly described species of the
genus, cannot possibly be confused with any of the other known species
in the nymphal stage* Its outstanding characters are the presenoe of
four prominent lateral thoracic projections, small dorsal thoracic pro
minences, serrate margins on the mesonotum, and prominent elevations on
abdominal segments six through nine* The adult may be distinguished chief
ly by the reddish-brown coloration in the basal third of the fore wings
and the basal three-fourths of the hind wings* They are very bulky crea
tures with a robust thorax, short abdomen, long fore wings, and large
hind wings*
DISTRIBUTION: B* rogersi is known to occur only in northwest Florida and
from one stream in Alabama, the Perdido creek, about two-thirds of a mile
north of the Florida state line* The species has been taken from one
locality east of the Apalaohieola river drainage, and that not more than
fifteen miles distant from the river* Westwards, rogersi is recorded as
far as Santa Rosa county in Florida, and in Escambia county, Alabama*
The species most closely related to B* rogersi are Carolina and
thompsonae, both of which are North Carolina forms* B. Carolina is known
from the Piedmont and Appalachian provinces, while B. thompsonae has been
found in the Appalachian only* (iee )<*)
ECOLOGY: With so few rooks in the stream beds of the sand-bottom streams
of Florida, the peculiar B* rogersi nymphs must adapt themselves to the
next best situations* The pebbly riffles in shallow water seem to meet
their requirements better than any others, at least the number of nymphs
found in these areas would seem to indicate this. "Dr. Traver's desorip-


331
Caenia hilarla, and Trioorythodee albilineatus all forms with opercu-
late gill covers as in Braohycercus* This would, therefore, seem to be
the riost logical place from which to suppose that the nymph came# If
this be correct, the nymphal habits of this species differ somewhat from
those described by Spieth (1938 3) for Brachyoercus sp from Indiana
and which were discussed above under B# maculatum. (See. ***? *
SEASONS The nymph is a last stage female taken on March 17#
DERIVATION OF THE SPECIES Probable derivation of thespecies has been
discussed under 13# maculatun
LOCALITY RECORDS Gadsden Co* 4 l/2 miles south of River Junction
(March 17, 1939, J. S. R., H. H, H,, F. N* Y., & L. B., nymph)#


>
tinuing northward into th mucklands of th Lake Okeechobee region, which
in burn is continuous northwards on the oast and west with the lowlands
of the coast*
The central highlands may be divided into two areas* The southern
half is entirely a lake region where almost every depression has its own
pond or lake; the northern part of this division not only includes lakes
ponds, but there are also numerous surface as well as subterranean streams
of all sises*
The Tallahassee hills and western highlands are rolling areas composed
of red-clay hills, well drained by many small streams* The Marianna low
lands, on the other hand, is made up for the most part of flatwoods, swampy
areas, and rolling sandy hills oovered by pine forests with few permanently
flowing streams*
Several large rivers arising in Alabama dnd Georgia flow through north
western Florida and empty into the Gulf of Mexico* In the east, the large
St* Johns river flows north along the border of the central highlands and
the coastal lowlands*
DESCRIPTIONS OF M3ITATS
Streams
Intermittent Creeks
In Florida, there are relatively few intermittent streams* These few
are, for the most part, merely connecting canals between swamps, ponds
or other bodies of water the level of which fluctuates continually according
to the amount of precipitation* As far as mayflies are concerned, they
are rather poor situations, and only the very tolerant Callibaetis and


415
adult Since Cloeon nyssa has single gills3 it should he included in
Neooloeon (on the basis of characters set forth by Traver) although Ide
places Cloeon triangullfera and C minor both species with single gills,
in the genus Cloeon, He comments as follows (1937: 241): Traver (1932)
has described a new species of this group and has erected a new genus TTeo-
olooon to include it. The nyraph of Meocloeon alamance Trav. is very similar
to the nymph of C* triangulifera described below and it would seem that the
species, although perhaps not identical, are very close to one another* At
present I prefer to leave triangulifera in the genus Cloeon. This paper
of Ide's brough to light two nymphs which, on the basis of the immatures
alone, would have fallen into IToocloeonj however, since adults were associat
ed with the nymphs, and these were found definitely to be Cloeon, it seems
reasonable to suppose that Neooloeon Is a synonym of Cloeon and represents
only a section of the genus.
In the disoussion of C. robropictum, it was indicated that there are
probably three phylogenetic stocks within the genus based on gill structure.
If the genus oan logically be divided into three such stocks, then Cloeon
nyssa would fall into the oldest that in which all gills are single.
DISTRIBUTION: £ nyssa is known from only two localities, both in north
western Florida. Three of the nymphs were taken from Holmes creek which
is a part of the Cboctawhatchee drainage system; the other specimen was
found in a small stream draining into the Chipla river, one of the Apala
chicola river tributaries, (-fee */)
ECOLOGY: From an ecological standpoint, the species is virtually unknown.
The stream from which the three nymphs were taken has been described above.
In the center of one of the branches of Holmes creek, there is an old stump


122
L* B*, nymphs). Nassau Co* 19*1 miles north of Duval county line
(August 28, 1938, H* H* H*, nymphs)* Okaloosa Co* Shoal river (Decem
ber 11, 1937, L. B., nymphs); Crestview (December 12, 1937, L B*, nymphs);
5*1 miles west of Walton county line (May 31, 1940, H. H* H* and L. B.,
nymphs); 2*3 miles east of Niceville (April 3, 1938, E* H, H* and L* J* M*,
nymphs); Niceville (June 7, 1938, L* B, adults); 3*6 miles north of
Niceville (April 3, 1938, H. H* H* and L* J* M*, nymphs)* Santa Rosa
Co* 7*1 miles west of Miltoxi (April 4, 1938, H* H* H. and L* J* M,
nymphs and adults); Paoe (June 1, 1940, H* H, H* and L, B*, adults)*
Taylor Co* Fenholloway river (May 29, 1940, H, H* H, and L* B*, nymphs
and adults)* Wakulla Co* ~ Smith Ci*eek (June 5, 1938, H* H, H*, F* M. Y*,
L. B*, nymphs and adults)* Y/alton Co* 1 mile north of Walton county line
(June 7, 1938, L* B*, nymphs); 2*1 miles west of Walton county line
(May 31, 1940, H* H* H* and L* B., nymphs); 7*3 miles northwest of Ebro
(June 7, 1938, H* H* H*, F* N* Y*, L* B*, adults and nymphs); 15.8 miles
west of Ebro (June 7, 1938, L* B., adults); 9*5 miles west of Portland
(May 31, 1940, H* H* H, and L* B,, adults and nymphs); Portland (April
3, 1938, H. H* II* and L* J. M., adults); 10 miles east of Freeport (April
2, 1938, H* H* H* and L* J* M*, nymphs); 5*4 miles east of Freeport
(April 2, 1938, H* H. E* and L* J* M*, nymphs and adults); 2 miles west
of Freeport (April 3, 1938, E. E* E* and L. J. M*, nymphs); 2.6 miles
west of Freeport (June 7, 1938, L. B., nymphs); 13*8 miles west of Free
port (June 7, 1938, L* B*, nymphs); 15*6 miles west of Freeport (June 7,
1938, L* B,, nymphs); 12*5 miles east of Niceville (April 3, 1933, E* E*
H. and L. J. M., adults); 11*4 miles east of Niceville (April 3, 1938,
E* E* H. and L. J* M*, nymphs and adults). Viashington Co* 5*8 miles


268
Spieth (1933: 351-353) conducted, that Ephemera 11a, along with Tri-
corythodee, occupies a distinct and separate pjaoe in the phylogenetic
history of mayflies* Needham, Traver, and Hsu (1935: 664), however, did
not agree with him, but gave no reasons for not doing so. My reasons for
accepting Spieths conclusions on the relationships of Tricorythodes and
Ephemerella have been given in the generic treatment of the former (p.*f£?).
Ephemerella trilineata ms. name
TAXONOMY: For some time, I considered Ephemerella trilineata to be a
variant of E. doria; however, reoent studies have convinced me that I
have been dealing with a new species. It may be distinguished from doris
by the coloration of the tenth tergite, by the presence of a median dorsal
abdominal stripe, and by the presence of ruddy bands on the distal ends of
the femora, as well as reddish markings on the femora.
According to either MoDunnoughs or Travers classification, E. tri
lineata belongs in the bicolor group, one of the larger ones of the genus
Ephemerella. The new Florida species is very close to E. doris and is also
closely related to E, temporalis, but differs from the latter by its much
paler coloration. Dr. McDunnough has examined a male imago of E* trilineata
and agrees that my specimens represent a new form.
DISTRIBUTION: In disoussing the range of this new species, it would be
best to first treat that of E. doris, for trilineata may prove to be a
subspecies of the former. E. doris was described Urorn the Piedmont of
North Carolina} paratypes are recorded from Withlacooch.ee river near Macon,
Georgia, but this locality is obviously in error sinoe the Withlacooohee
does not flow Within a hundred miles of Maoon. Traver has, in addition,


349
22 miles north of Tampa (March 25, 1938, L. £., nymphs)* Putnam Co.
Melaka (October 12, 1939, E. L* Pierce, adults); 30 miles east of Gaines
ville (October 2, 1937, L. B., nymphs and. adults); 1.2 miles north of
flatka (October 2, 1937, L. B., nymphs); 11 miles north of Palatka (Octo
ber 2, 1937, L. B*, nymphs ad adults). Taylor Co. 6.6 miles east of
Perry (February 5, 1938, L. B., nymphs;. Volusia co. DeLeon Springs
(August 5, 1938, J. A. Preer, adults)* Walton Co. 1.4 miles west of
Portland (June 7, 1938, li. h. ii., F. K Y, L. B., nymphs).


81
17
18 (17)
18
lo truo intercalarles In fore wing in position indicated above*
Sale forceps with two short terminal segments (see figs* 19 and 20).
Lept ophlebiinae (19)
Hind wings absent. Forceps three-segmented; an ovoid swelling
at base of second segv.ent on inner margin (see fig* 21).
Trloorybhodes albilineatus
Kind wings present. Forceps three-segmented, no swelling on
second segment (see figs* 14 and 18).
Ephemerella trilineata
19 (17' ) Kind wings reduced in size and venation; distinct costal angulation
half-way to apex (see fig. 22).
(20)
19* Kind wings larger, venation more prominent; no costal angulationj
costal margin slightly concave at middle (see fig. 23).
(22)
20 (19) Costal angulation of metathoracio wing obtuse; no sag in fork
of M of fore wing (see figs* 22 and 24)* Penes long, simple,
without reflexed spur; forceps base of male undivided (see fig.
25) Eubanal plate of female slightly emarginate.
Choroterpes hubbelll ,
20 Costal angulation of hind wings acute; a distinct sag evident
in fork of MA of fore wing (see figs. 19 and 26). Penes with
reflexed spurs; forceps base deeply cleft (see fig. 27), Apical
margin of subanal plate of female deeply cleft.
(21)
21 (20*) Subcosta of hind wing ends in margin at outer side of oostal


95
30* Ho euoh prothoraoic tubercles*
Braohyoercus maculatura
31 (29*) Average length of mature nymphs 5*0 mm. range 3.9-6*7 mm.
Numerosas yellow spots scattered over pro- and mesonotum. Pre
dominantly pond forms.
Caenls diminuta
31' Average length of mature nymphs 3*2 mm. -- range 2*6-3.8 mm.
No yellow spots on pronotum; on mesonotum yellow spots at bases
of wing pads and a pair of eubmedian spots. Predominantly stream
foms.
* Gaenis hilaris
32 (20') Gills on abdominal segments 1 and 2 four-lobed, on 3-6 double,
and single on seven. Maxillary palp two-segaented (see fig. 25).
Callibaetis (33)
32* Gill lamellae double on first abdominal segnent only, or single
on all abdominal segments. Maxillary palp either two or three
segmented.
(35)
33 (32)
33*
Maxillary palp shorter than body of maxilla; second segment of
palp about one half the length of the first segments width of
first segment about one-half its length (see fig. 25). Seventh
gill with small recurved flap (see fig. 26).
Callibaetis pretiosus
Maxillary palp equal in length to body of maxilla; second seg
ment of palp approximately equal in length to first segBSSfcj
width of first segment less than one-third its length (see fig. 27).


185
ISOTYCHIA Eaton
Eaton proposed the name Isonychia for manca Eaton and ignota Walter,
but in 1881,under the impression that the generic name mas preoccupied by
Isonyohus Manhh*, he suggested the name Chirotonetes to replace Isonychia.
kcDunnough (1923: 47) reexamined the group and concluded that according to
the International Rules of Nomenclature Isonychia Eaton is valid. In his
paper, Kchunnough also wrote a key for the separation of the genera of
the Ciphlonurinae as known at that time.
The genus in North America contains twenty-six described species*
The descriptions of tus majority of them were given by Traver who described
sixteen of the species; McDunnough has described three and the remainder
ware described by various other authors. Although identification is tenta
tive, it seems that there are at least two new species in my collection
from Florida and southern Alabama.
Taxonomically, the nymphs are still poorly known, for only eleven have
been associated with their adults. Identifications of immatures based on
the literature must therefore retain an element of doubt, especially sinoe
there is such close resemblance between the nymphs of the various species.
One of the characters frequently used in separating nymphs, and one which
I had also employed, I have now come to believe is merely an individual
variation the length of the tibial spur of the fore leg compared to the
length of the tarsus of this leg. One nymph in the pneultimate instar was
kept in the laboratory for several days, and during this period it molted
once. An examination of the exuviae showed the tibial spur to be quite
long and sturdy, but comparison with the spur on the aotual nymph revealed


8
Whales, Elephants, Lromedaries and Camels; these, I confess are the
Colossus and ^ajestic pieces of her hand; but in these narrow Engines
there is no re curious matheaatioks*"
The epkemerids of Florida being so little known, it was certain that
a study of these insects would reveal much that was new The only other
region, in the south that had been at all intensively investigated was
North Carolina (principally frota a taxonomic viewpoint), and since the
fauna of North Carolina is, for the most part, characteristic of mountains
and hilly countxy, it gave little indication of what was to be expected in
tho lowland areas of the more southern Coastal Plain and the flat peninsula
of Florida*
The approach has been from the standpoints of taxonomy, zoogeography,
ecology, life histories, imbits, and phylogeny. All of these fields of
study viere kept in mind throughout the period of research, and in presenta
tion of the results uniformity of treatment of each species is attempted.
However, as would be expected, there may be much information on one species,
while another goes begging* This is the natural result of the relative
accessibility or inaccessibility of the species to a student working from
the University.
In order to determine just which species occurred in Florida, where
each lived, how it lived, and the various features of its behavior and
activities, much travel was necessary, for a relatively small percentage
of Florida species occur within easily available situations near Gainesville*
Great gaps still exist in the information gathered in the western part of
Florida, and only with much further work will these be filled in*
Sinoe the mayflies of tho whole state are included in the study, and


276
at * S. Huvy. ,'/41 (February 4, 1833, H* II* H*, F* II* Y, L, E, nymphs
and adults)* Hillsborough Co* Hurrah creek at Picnic (March 26, 1938,
L* 3., nymphs). Holmes Co. candy creek (December 11, 1S37, L. B.,
nymphs). Jefierson Co. Drifton (February 5, 1938, H* II* H*, F. !T. Y.,
L. 3*, nymphs). Liberty Co. Ilosford (¡arch 17, 1939, J. S. E., H* H* H.,
F. IT, Y., L. B*, nymphs); Little Sweetwater creek (December 10, 1937, L* B.,
nymphs); Sweetwater Creek (November 4, 1938, L. B., nymphs; December 1,
1939, II* H* H*, W II* McLane, L. B*, nymphs)* Maricn Co* Cklawaha river
at Eureka (February 12, 1938, L. B*, nymphs). Putnam Co. P.ed-\mter Lake
(Larch 26, 1939, C. J. Coin and L. B., nymphs and imagos, adults reared
March 29, 30, and April 4). Washington Co* Chactawhatchee river (April
2, 1938, H* E* H* and L* J* H*, adults); Holmes Creek (December 11, 1937,
L. B., nymphs)* 5.8 miles south of' Vernon (April 2, 1938, H* H* H* and L. J*M. ,
nymphs)*
Ephemera11a apalachicola ms* nam8
TAXONOMY; Ephemerella apalachicola is closely related to E* defioiens
bub differs in the nymphal stage in having its femora banded with yellow,
longer, more attenuated tarsal claws, and a narrow brown band on each of
the caudal filaments, also the nymphs of apalachicola are slightly smaller
than defioiens. Following Travera division of the genus Ephemerella, apal
aohicola would fall into the serrata group along with defioiens. Characters
shared in common with defioiens and which are different in other members
of the group aret the complete absence of a maxillary palp and absenoe of
dorsal abdominal spines.
The ol6(¡N) of the nymphs of defioiens as depicted by Morgan (1911: 111)


151
which emerged when the nymphs were first brought into the laboratory and
those which emerged after one or two months under these conditions.
The latter are somewhat smaller, having been dwarfed by confinement or
by food which was not conducive to full growth.
LIFE HISTCtY The subimago emerges in late afternoon after sunset, flies
to a nearby support where, after eighteen to twenty-two hours, the final
molt takes place and the adult is soon ready for mating.
The mating flight begins just after the sun has set and continues un
til darkness has fallen. I was unable to distinguish the individuals in
the swarm as darkness fell and consequently did not determine the entire
length of the flight. The following description of swarming is taken from
my notes of April 1, 1939 "At 7i00 p* m. while standing on the bridge
over Hatchet creek, I noted several _S. smithae females flying up and down
the stream in the act of oviposition, but could see no mating flight of this
species... While the 3. smithae females were ovipositing, I suddenly noticed
a bit of aotivity just below me, wnich rapidly began to increase. It was
becoming rather dark, but by shifting my position, I could see that this
activity was caused by a group of S. proximum males in their mating flight.
The swarm was small, composed of not more than twenty males. These insects
flew up and down continuously, the upward flight was rapid, the downward
slower, more as though the insects were drifting* I paced off the hori
zontal distance covered by the swam ana found it to be almost negligible,
not more than five feet and this was not varied during the fifteen minutes
which I observed the insects. At 7sl5 it became so dark that further ob
servation was impossible.
"How and then, a female was seen approaohing the swam, entering it


299
CAENIS Stephens
The genus Caenls was described in 1835 by Stephens v/ho made the
European Ephemera halterata the genotype* At the time of publication
of Eaton's monograph, only two species of Caenis were known from North
America, seven from Europe (he inoluded Brachycercue harrissella), one
from Asia, and two from Africa. Hagen (1861s 54-55) listed three species
in his "Neuroptera of North America" but Eaton synonymized diminuta and
arnica* The next general review of the genus in North America was that of
¡vlcDunnough (1931s 254-264) in his paper on the Caeninae* In this, he
treated ten species, of which five are described as new. Traver (1935s
643-654) in "The Biology of Mayflies" again treated the North American
species of Caenis, describing two new species, and redescribing the ten
that had been discussed and described by McDunnough* Since this publi
cation, there have been no new speoies of Caenis recorded for North America
proper, but Traver (1838s 22-24) described three species from Puerto Rico
without naming them. These are known chiefly from the nymphs and con
sequently their relationships with the Florida species cannot be determin
ed.
Campion (1923) discussed in full the synonymy of the generic name
Caenis and ereoted the genus Ordella to include part of Caenis; the
remainder was placed under the name Brachycereus. Lestage (I924d) follow
ed Campion and suggested that the family name be changed from Caenidae
to Brachyoercidaej however, McDunnough, without stating a reason, restored
the American speoies to Caenis and used Caenidae to include Brachyoorous
(s Eurycaenls), Tricorythodea (* Tricorythus as used for North American


181
must retain a shad of doubt, but my specimens agree very olosely with
Tracers description of the nymphs from Georgia,
There is a single nymph among my specimens which resembles S, soecio-
sum in all respects, except in the fact that there is a broad, black, me
dian line running from the posterior margin of the head to the middle of
tergite ten* This is probably only an individual variation, for the nymph
was taken in company with typical forms of S# speciosum,
DISTRIBUTION: So few locality reoords as are available hardly justify
generalizations concerning the distribution of a species. Nymphs have been
taken from only three localities, two in Florida and one just beyond the
Florida line in southern Alabama, The type locality of S, speciosum is
very dose to the Fall Line and the other localities given by Traver also
abutt this physiographic dividing linej whether the species enters the
Piedmont or not I have been unable to determine. From the evidenoe at hand
it would seem that _S, speciosum is a Coastal Plain species which only
occasionally enters the Piedmont, In Florida, the species is confined to
the westernmost portion extending from just east of Defuniak Springs to
the Styx river in Alabama, I have collected rather extensively in more
easterly and southern regions but even though I searched particularly for
Siphloplecton nymphs, none were found, Sven those localities from which
nymphs had previously been taken produced not a single specimen on return
trips. Probably the speoies is confined to an area extending eastwards
from Augusta, along the Fall Line, into the Alabama river drainage which
it follows southwards to its limits in this direction# C3ee 1^'
ECOLOGY: In the Styx river, from which nearly all of my specimens were
collected, the inseots were found at the shore among the debris which had




403
approximately the same time as sunset* The final molt tabes place within
ten to twelve hours In the laboratory, a female emerged as late as
6:30 p m. on August 23, on the morning of August 25, it was quite lively;
however, at 9:00 p m. on the latter date, it was beginning to shrivel and
showed only the slightest signs of life Under ideal conditions it would
seem that maximum possible life for females of this species is approximately
fifty hours.
Nymphs have been kept in the laboratory in an effort to rear adults;
of these, some viere rather immature and remained alive long enough to under
go ecdysis The following is a summary of the data on the molting*
Nymph 1. Two-thirds grown
Collected at 3*00 p* m 8/13/38
Molt about 1*00 p* m * 8/15/38
Molt between 9:15 p. m 8/l9 and 9:30 a. m.
* 8/20/38
Molt 8/21/38
Died 8/24/38
Nymph 2* One-third grown
Collected about 10:00 a 8/l0/40
Molt between 10:00 a m# and 4:00
p m. 8/14/4O
Died . 8/16/40
M;ymph 3 Collected about 10:00 a m * 8/l0/40
Molt between 6:00 and 9:00 p m s/lo/40
Novi in last instar


397
the ecology of the genus. Of the former species, Ide says "Nymphs of
this mayfly were abundant in the Mad river at Hornings Mills where they
were found among pond weeds and lily pads." Concerning C. beHum "The
nymphs of this species were very numerous in the moderately rapid water of
the stream at Primrose where they were clinging to the upper surfaces of
the stones."
Phylogenetically, all the Baetinae form a rather compact group. Spieth
derived these genera from a common stock considering those possessing well-
developed hind wings to be more primitive than those in which these wings
are absent. Based on the degree of reduction of hind wings, Centroptilum
would be at approximately the same level of development as Baetis and Aoen-
trella with Calllbaetis the most primitive, Heterocloeon an intermediate
form, and Pseudooloeon, Cloeon, and Neocloeon forming the most highly de
veloped group in which the hind wings are completely absent. Genitalia do
not seem to offer any indices to phylogenetic relations of the genera, nor
does eye shapej even nymphal characters, as far as studied, do not appear
to indioate true relationships.
Centroptllum vlridooularis Berner
TAXONOMY Centroptilum vlridooularis is the most recent addition to the
genus and has been described both in the nymphal and adult stages. "On
the basis of a combination of characters (mesothoracic color, red markings
on tergites 2-6, color of tergites 7-10, and presence or absence of a pro
jection on inner margin of second forceps segment), Centroptilum viridocularis
is distinct from other described species. Comparison of Traver's drawings
of the metathoracio wings (1935) of same species of Centroptilum with those


364
in north and central Florida this is true almost without exception.
The distribution of spinosus is rather interesting in that four
physiographic provinces are involved: the Canadian shield, the Adirondack
province, the Coastal Plain, and the Piedmont. Apparently geographic bar
riers are not of importance in determining the range of this species. (See **/> /l).
ECOLOGY: Without doubt, this is one of the most adaptable of all Florida
mayflies. As an example of its ubiquitousness, the following is a fairly
good illustration. Nymphs were observed in a flume leading to a ram at the
origin of Little Sweetwater Branch, Liberty county. The flume, constructed
of wood, had its sides oovered with a thin growth of algae, and there was
a continuous flow of water through the trough. The level of the water was
not much over two or three inches, yet it supported a rather large popula
tion of B. spinosus nymphs of all sizes. I have found immatures along the
edges of creeks where the water was practically stagnant and the nymphs were
living under masses of dead leaves and silt which had acemulated in these
regions. In contrast, the nymphs have been found in the most rapid parts
of the most rapid Florida streams, and in them they could be found in all
regions ranging from the slowest to the swiftest.
Those streams in which there are dense growths of Vallisneria, Sagittaria,
and Potamogetn support, by far, the largest populations of B spinosus nymphs.
The reason for this abundanoe is seen in the tremendous amount of surface
presented by the thick masses of this submerged vegetation. Covering the
surfaces of the leaves there is an abundance of food materials in the
form of algae and diatoms. As an example of this type of stream, the Santa
Fe river cannot be exoelled, if that portion in the region of Poe Springs
be examined. Here, the Vallisneria and Sagittaria are so thick that in


285
was collected at Blowing Rock, North Carolina* No member of the simplex
group has ever before been found in the Coastal Plain, or even in the
Piedmont (unless Catactin creek, a tributary of the Potcmoc river, lies
in this province)* (Jee snap ^
ECOLOGY In June 1940, I collected from Perdido creek, but found no trace
of E* hirsuta The creek is swiftly flowing and fairly deep. The deeper
portion (three to four feet) has almost no plant growth, but the shallower
and quieter margins are choked with vegetation principally Vallisneria,
Potomegeton, and a Bedge, among the higiier plants, together with the alga
Batr ac o spe ranaa sp* The latter plant is very thick in the stream, and forms
dense masses covering the other vegetation* In this alga were found num
erous mayfly nymphs, and they were also very common on the blades of the
Vallisneria and among the leaves and stems of the Potomegeton; but no
examples of E* hirsuta were taken in either of these situations. Along
the shore where the flow is almost negligible,Persecaria and leaf drift
are the dominant mayfly refuges* Although I have not been able to find the
nymphs of Ea hirsuta, a study of the external anatomy of my specimens taken
by Hobbs and Mu rehand leads me to believe that the nymphs must either live
in the algal mats or among the leaf drift and silty matter deposited about
the bases of the Perseoaria stems* The nymphs, as the name of the species
indicates, are covered on the dorsum of the thorax and head with long, some
what matted hairs. The hairs also oover the femora and the anterior part
of the abdomen, acting as a protection from the debris which might collect
on the insects. Another strong point supporting my contention as to their
habitat preference is based on a comparison of the body shape of E. hirsuta
with that of E* trilineata. The latter species, whose habits have been dis-




170
Apalachicola river* It is also known from acon, Georgia which lies
in the drainage of the Oomulgee river, at the edge of the Piedmont*
The first stream drains into the Gulf of Mexioo, the seoond into the
Atlantic Ocean* (5*e m*? s).
ECOLOGY Aside from the fact that the nymphs of Campsurug are believed
to be burrowera, and appear to be confined to fairly large rivers, nothing
is known concerning the ecology of any species of this genus*
SEASONS* Camp sums inoertus emerges during the sunmer, according to
information gathered from various people living along the Apalachicola
river* The Florida specimens here recorded were taken about July 29* The
insects frcm Georgia which Traver used in her description were collected
in August and on September 4*
LIFE HISTORY* The developmental stages are not known for any North Ameri
can species* Because of the vestigial condition of the legs and the con
sequent faot that the winged form is entirely aerial, the subimaginal
stage must necessarily be brief. Morgan (1929* 63) says "The subimago
stage of Campsurug segnls [South American] is probably of brief duration,
far different from that whioh is characteristic of its related Hexagenia
bilineata and Ephemera simulans in which this stage lasts twenty*four
hours or more* In these and in many other species this subimago period
is the one in whioh there is a rapid elongation of the legs and oaudal
setae* These changes are most obvious in the males, the lengthening slen
derness of whose front legs is zigzagged across the encasing subimago skin
as if in a stocking much too short* No such growth of the legs seemed to
have occurred in these Campsur us subimagos*"
DERIYATIuN OF THE SPECIES* According to Traver (1935* 287) the male geni'


34
29*
30 (29)
30
light reddish shadings on dorsuu.
? Intercalarles in mid-posterior margin of forewing occur
singly; vitta brown, margin straight; 20-25 cross veins in
forewing; posterior margin of forewing unicolorous (see fig*
34),
Callibaetis floridanus (30)
Intercalarles in mid-posterior margin of forewing occur
either in pairs or singly. Abdominal segments 2-o whitish
hyaline with prominent brownish shadings on dorsum.
9 Intercalarles in mid-posterior margin of forewing occur
in pairs; vitta brown, undulatory; 35-40 cross veins in fore
wings; posterior margin of fore wings marked with alternate
yellowish and brown areas (see fig. 33).
Callibaetis pretiosus
Fore wings odorless or only slightly colored; spots covering
body brown or reddish brown; body coloration somewhat dulled.
Central and north Florida.
Callibaetis floridanus minor
Fore wings tinged with brown; spots covering body red; body
coloration intense. South Florida.
Callibaetis floridanus floridanus
31 (28') Marginal intercalarles of fore wing single.
Centroptilura (32)
31 Kargina! intercalarles paired (see fig. 15).
32 (31)
(33)
Abdominal tergites 2-S with reddish areas.


167
bution The southernmost records of undoubted simulans are from Penn
sylvania, Ohio, and Illinois It therefore seems almost certain that
the Florida form, whether it be simulans or a closely related speoies,
originally entered the Btate from more northern regions# Since neither
simulans nor any of its close allies has ever been taken in the eastern
Coastal Plain or the more southern parts of the Appalachians, it does not
seem likely that the ancestors of the Florida form came by either of
these routes* On the other hand, the large streams of the Mississippi
drainage would appear to furnish an ideal highway for the southward migra
tion of E simulans, and once established in the southern Coastal Plain
the speoies might easily have spread eastward to Florida, finding suitable
habitats for its nymphs in the mixture of sand and silt along the shores
of the larger and more sluggish streams, and in the sandy lake bottoms
Aside from the Florida specimens here reported, the only known reoord
of the occurrence of Ephemera anywhere in the eastern or southern Coastal
Plain is that of a single adult (speoies unknown) from Tallulah, Louisiana,
taken in airplane towings at an elevation of two thousand feet It is,
of course, possible that this speoimen had been carried for a long distanoe
by wind currents5 but, in view of the brevity of adult life and the fragi
lity of these inseots, it seems more likely that this specimen had not
traveled far. Its presence in Louisiana tends to support, even though
weakly, the hypothesis that the genus has been able to reach the Coastal
Plain by way of the Mississippi riverj and of the possible routes for en
try of the group into Florida, this seems by far the most likely*
LOCALITY RECORDS Clay Co* Kingsley Laxe (May, 1936, J. S, R, nymphs)


290
tiating the evidence from the adults, Spieth also pointed out nymphal
characters such as mouth parts and gills which show closer affinities to
Ephemerella than to Caenis and Brachyoercus. In a recent verbal communi
cation, Dr. Spieth also stated that the eggs of Tricorythodes and Ephem
erella are fairly similar*
Tricorythodes albllineatus ms. name
TAXONOMY For some time, I have debated whether or not the specimens in my
collection from Florida represent a nexr species; however, I have concluded,
on the basis of certain color differences, that these insects are worthy
of a new specific name. The sprinkling of numerous black dots on the
femora (given by Traver as a diagnostic character) would place the Florida
specimens as atratus, but judging from McDunnoughs description my insects
have more limited dark markings on the abdomen than does atratus and
are characterized by a pale median line on the dorsum of the abdomen.
There is also a slight difference in the leg measurements of the males
of the two species. The colorational characters are quite constant in
albilineatus, particularly the pale line, even in series from widely separ
ated localities.
DISTRIBUTION T. albilineatus is generally distributed over Florida wherever
there is permanently flowing water. Nymphs or adults are known from as far
south as Hillsborough County, and as far north and west as the southern
part of Escambia County, Alabama. The species occurs in an almost con
tinuous belt starting in Hillsborough County and passing westward to the
above locality* The geographic distribution is probably limited by the


203
as to the seasonal relations of the species. However, certain tentative
conclusions can be drawn. The earliest records for nymphs in their last
instar are in March, and records for this stage extend to May 31. In
March, nymphs in the tertiultimate instar were collected, these probably
would have emerged in Aprilj another group of half-grown nymphs was taken
on Lecember 1 these are ones which would have emerged during the spring.
It seems then, that emergence probably stf rts in late winter and proceeds
through the spring and even well into the summer, but there is no trans
formation during all and early and middle winter#
LIFE HISTORYi The small amount of data concerning life history has been
summarized above under seasonal range#
DERIVATION OF THE SIECIESi Beoause the most olosely related species are
northern or mountain forms, it appears more likely that the Florida species,
E. ehoctawhatch.ee, became isolated from one of these northern species, or
its parent stock, in the southern Appalachians and then moved southward
through the Chattahoochee which drains the foothills of this mountain range.
An origin from a stock which was southern in distribution in ancient times,
but moved northward with the oulmination of the Pleistocene and left E#
choctawhatoh.ee stranded in the lowlands of the Coastal Plain, appears to be
less likely. The discovery of nymphs in the Chattahoochee drainage of the
Piedmont strengthens the former hypothesis.
LOCALITY RECORDS! Gadsden Co. 4 l/2 miles south of River Junotion
(March 17, 1939, J. S# R., II# H# H#, F. N# Y#, L. B., nymphs)# Liberty
Co. 10 miles south of River Junction (March 17, 1939, J. S. R, H. H# H#,
F# N# Y., L. B., nymphs)| Sweetwater creek (December 1, 1939, II. H# H., W.
M. McLane, L. B#, nymphs). Okaloosa Co. 5.1 miles west of Walton county


69
summer and may freeze over during prolonged, periods of cold The filling
of lake and pond basins is rapid and the great amount of decaying vegetation
quickly builds up deposits of peat, which finally replaces the water of the
marshes. The level of the water is subject to great fluctuations accord
ing to the amount of' rainfall, and at times the marshes go completely dry,
but over the greater part of the year, water remains in them* The marshes
are definitely acidic, some having a pH ranging below 3*Sj but this con
dition is local, and at different points in the same marsh the pH may range
frcoi 3*6 to 6*0 or higher* The organisms found in the marshes are not
essentially different from those occupying similar habitats in ponds and
along lake margins, for conditions in these marshes are very much like
those of the pond margins* The principal differences lie in the facts that
emergent vegetation occurs throughout the water rather than being confined
to a shore zone, and in shallowness, the marshes being not much more than
three feet deep at their deepest point*
(2) Another type of marsh found in the central part of Florida is very
similar to the above except that vegetation is principally Persicaria and
saw grass (Hariscas jam&icensis), with the fontederia much more limited in
extent and with no Kymphaea present however, the organisms inhabiting
these marshes are identical with those found in the other types.
(3) The Everglades > The Everglades are so distinctive that they require
discussion under a speoial category. "The Everglades occupy a nearly level
plain, which slopes from 1-5 feet above sea level at the south shore of Late
Okeechobee to sea level at the tip of the Peninsula, a distance of more than
one hundred miles. One the west the Everglades merge into the Big Cypress
Swamp, which presumably is a few feet higher. On the south and southwest


28
Within some families, the length of tarsal segments of the fore legs of
the males is used to distinguish between genera, and in some oases this
character has been relied on to suoh an extent that it is impossible
to identify a female to genus, unless males can be definitely associated
with her* It seems that much further work is needed in these groups
in order to clarify the situation* Within the genera, leg structure
is little used taxonamically, although 1 believe that relative proportions
of the various parts will prove useful when measurements are made*
Another character frequently used, and rightfully so, is eye struc
ture, but tills character again is applicable only to males* Sexual
dimorphism in mayflies is so very pronounced that unless one is familiar
with the group, males and females of the same species might easily be
mistakenly placed in different genera* Among the male ephemerids, there
are all gradations in structure of the oompound eyes from a simple type
to those which are completely divided and enormously enlarged into bizarre
shapes* Whether or not the eyes are divided is used as a criterion for
separating the Baetid&e from the Heptaganiidae, and in some oases the
character is also used as a generic differentiator* There appears to be
a definite correlation between eye sise and shape and the night- or dagr-
flying habit8 of the species* Those mayflies mating at dusk or after
dark have small eyes which are approximately of the same size in both
sexes, or but slightly larger in the males* In Palingenia (European)
the female is approached by the male as she floats on the surface of the
water, and in this genus, the eyes of the male are a little smeller than
those of the female* The males of the day-flying species have huge eyes
which are far larger than those of the females*


158
Dr* Traver kindly sent me a s5ngle male of the former, deterained by her
self, frcm Lake Worth, near Albany, Georgia* Comparison of this speci
men with, my series of roem and orlando showed that the males, at least,
are practically indistinguishable* Such differences as do exist between
weewa end orlando have been pointed out in the discussion of the former,
and in the key* Although for the present I am retaining them as distinct,
future studies will probably show that the two are synonymous or no more
than subspecies; it is quite probable that they are only -varieties or
races of H* limbata or one of its kindred species. The fact that typical
orlando occurs in Lake Vforth, which is merely a dammed up tributary of the
Flint river, itself a tributary of the Apalachicola river from which weewa
was described, is consistent with the idea that weewa and orlando are the
same or only racially distinct.
In 1937, Traver recorded H* orlando from Tuscaloosa, Alabama, and in
this paper she stated that "four females taken along with the males are
evidently of the same species* Another female aocompanving them has the
dark markings on the abdomen much reduced; it may be only a very pale form
of the same species." I am of the opinion that the latter specimen was
a female which might very well be the insect which Traver named weewa, and
that the darker specimens were her orlando. It appears, therefore, that
the two species have been erected on sharaoters which vary with seasonal
changes or on individual variations* This former possibility is reinforced
by Spieths study (1938) of seasonal variation of color pattern within a
species*
Also in the 1937 paper, Traver stated that the nymphs of H. orlando
are not known failing to recognize the fact that she, herself, had des-


S79
observed this nor has the flight been reported by other workers. Morgan
(1913s 392) described the flight of an unidentified species of Baetis as
follows: "Actual mating has been observed but a few times. The most sat
isfactory observation was made in May, 1911, upon a swarm of Baetis,which
were flying near Cascadilla Creek just after a shower. Most of the time
they were not flying much above the level of the eye so that they could be
clearly seen. Large numbers continually settled on bushes and upon my cloth
ing, and there appeared to be about equal numbers of males and females.
Many matings occurred, but in on y seven could the positions of the insects
be seen at all. The male of one of the couples flew up and attached him
self beneath a female, pressed the dorsal side of his head against the
ventral side of her thorax and extended his fore-legs upward, in order to
clutch her prothorax. The setae of the female extended straight out posteri
orly, but those of the male were pointed forward over his back so that
their tips projected between the heads of the two insects. The position of
the abdomen could not be clearly seen, but judging from that of the setae,
it must have been recurved in order to insert the penes inside the egg
valve. Copulation did not last more than half a minute. When in copula,
each pair was borne diagonally downward to the ground, but always separated
immediately upon touching it."
Needham discussed the mating flight of other species in 1935i "Baetis
appears to prefer the early forenoon. On almost any calm, bright morning
in cummer they may be seen from the high bridges over Fall Creek at the
Cornell University campus, filling the air of the gorge like bits of floating
thistledown."
From my observations on numbers of B# australis in Florida streams, it


tal forms and the latter speoies is also probably of northern origin*
Hobbs (1940) has hypothesized that the crayfish now occurring in
Florida have been derived from migrants from the north or from the west}
his evidence indicates that the western element is much the larger* A few
of the nortnern species of mayflies do appear to have swung westward around
the southern Appalachians and thence into the Gulf Coastal Plain and Florida*
In this sense only* can any part of the Floridian fauna be considered of
western origin*
Among the factors that may be used in explaining the present distribu
tion of rheotropic mayflies in Florida, temperature may have exercised a
considerable influence* In west-oentral peninsular Florida that is,
in the Tampa region the mean annual temperature of the air is 60 degrees
F1-, while in the northwestern part of the state, where the principal part
of the continental fauna is oonoentrated, the average temperature is nearly
ten degrees lower* Since temperatures in streams are less subjeot to varia
tions than those in air, it is likely that average annual temperatures are
more important to aquatic organisms than to terrestrial forms, for which the
extremes of temperature are more likely to be the critical factors* It
seems reasonable to suppose that the score or so of mayfly species common
to peninsular Florida and the western part of the state must have relatively
wide limits of temperature toleration* Those speoies having more restricted
temperature toleration have remained confined to the northern and northwestern
parts of the state*
Dispersal of mayflies
The two most important factors involved in the dissemination of may-




252
HAJBEPHLEBIA Eaton
Habrophlebia is a somewhat more diversified genus in Europe than
it is in North Americas several species are known from the former continent
while only two have been described from the latter#
The nymphs are most easily distinguished frc-m other Leptophlebines
by the structure of the abdominal gills which are filamentous, consisting
of two clusters of slender filaments# Likewise, the adults are easily iden
tified by the shape of the male genital organs, and by the venation of the
metathoraoio wings#
Habrophlebia is known in North America only from the east and south- .
east, but even in the southeast its published records include only moun
tainous regions#
(rills and genitalia, two excellent phylogenetic indicators, show
pronounced differences in this genus from those of any other in the sub
family# The hind wings offer still a better indication of relationships
and on this basis, Habrophlebia would seem to be derived from the same
stock which gave rise to Choroterpes, Habrophlebiodes, Thraulodes, and
Thraulusj its closest affinities are, however, with Thraulodes
Habrophlebia vibrans Needham
TAXONOMY! Habrophlebia vibrans was described from New York by Needham
in 1907 and recorded from the Black Mountains of North Carolina by Banks
in 1914 as H# jaoosa (jacosa was synonymized with vibrans by MoDunnough
in 1925)# These are the only references to this species until 1935 when
Traver described the form in the "Biology of Mayflies". During Dr#


This dissertation was prepared under the direction of the Chairman
of the candidates Supervisory Committee and has been approved by all
members of the Committee* It was submitted to the Graduate Council and
was approved as partial fulfilment of the requirements for the degree of
Doctor of Philosophy.
Date
Zj f y/
Supervisory Committee*
Chairman
^OaACl.


143
and closing them in the V-shaped angle Thus, their surfaces are cleared
of the mud thrown back by the hind legs, and thw water is continually
circulated about them"
Hexagenia limnophila nymphs are rather adept swimmers. When they
are placed in a dish of water in which there is no silt or sand for bur
rowing, they will swim vigorously around seeking to escape and continually
butting their heads against the sides of the container* The burrowing
habit is so strongly developed that, under these conditions, small nymphs
will seek larger individuals and attempt to burrow under them Swimming
is aocaaplished by wave-like undulatory motions of the abdomen and up
and down sweeps of the caudal filaments. The gills seem to play little
or no part in thiB activity* Morgan and Grierson (1932* 235^experiment
ing with Hexagenia nymphs from which the gills had been removed, found
that the gill-less individuals swam, almost as well as, but more slowly
than, those with gills
The method of feeding is similar to that of an earthworm, in that
the nymphs feed as they burrow Examination of the digestive tract of
immatures showed the presence of a few diatoms and some cells which seemed
to be algae, but for the most part the contents were not determinable*
Surprisingly, there were no sand grains in any of the digestive tracts
examined*
LIFE HISTORY* I have not determined the length of the nymphal period,
but from emergence data it would seem to be approximately one year Reave
(1932) on the basis of statistical measurements estimated that H occulta
took two years to go through its life history in Lake Winnipeg Spieth
(1936 and 1938) studying Ephemera simulans and H* occulta in Lake Wawasee,


148
they are during July and August, and they continue to decrease in size
in September and early fall until emergence stops completely* There may
be a few isolated individuals on the wing during inter-emergence periods
but they are scarce and difficult to find.
Just prior to emergence, the nymph, ordinarily negatively phototropio
and positively geotropic, reverses these tropisms and swims from the
lake bottom to the surface, where it breaks through the surface film and
the adult immediately bursts free. The winged inseot rests a moment, and,
if not taken by a fish, flies to shore where it alights on the nearest
available support. At the time of emergence, the predators became extreme
ly active and gorge themselves on nymphs and subimagos* I have observed
subimagos "popping out of their nymphal skins at the surface, and at the
some time many bass and other fish striking at them. At the same time,
birds vrere sitting on the trees and bushes along the lake shore eagerly
awaiting the advent of the inseets, and whenever one would approach a
bird immediately seized it,
Subimages taken into the laboratory molted by the next evening after
a resting period of about twenty-four hours. The single female reared in
the laboratory emerged in the late afternoon on August 20,and underwent
its subimaginal molt between 9:00 and 10:00 p* m, August 21, Luring the
afternoon of August 23, the insect died, after a life in the winged stage
of about seventy hours,
I have not observed the mating flight of H, limnophila, but on one
occasion I did notice restlessness on the part of a large group of these
insects about thirty minutes before sunset, I have been told that the
species forms large swarms which fly out over the lates just about sunset,


216
Mexico), and these are distributed generally throughout the continent.
It was mentioned in the discussion of Kabrophlebiodes that L&ptophle-
bia, Paraleptophlebia, and Elasturus form a closely knit group, all de
rived from a common progenitor. Spieth (1933s 346) considers that the
Leptophlebines represent primitive branches of a major division of the
mayflies. From a study of the morphological characters, Spieth concluded
that Leptophlebia (Paraleptophlebia) and Elasturus showed a close affinity
and that the Leptophlebiinae "stand comparatively low on one of the main
branches of the evolutionary tree of mayflies,"
Paraleptophlebia volitans (McDunnough)
TAXONOMY* Paraleptophlebia volitans was described by McDunnough in 1924
from Quebec. On the basis of genitalia, it stands alone. There is a
pair of reflexed spurs on the penes whioh are U-shaped; several other
species also have the reflexed spurs, but in them the shape of these
structures is entirely different. On the basis of presence and shape of
these spurs, volitans may be closely related to guttata.
The nymphs from northwest Florida are fundamentally like those of
Alachua county, but differ in having a brownish tinge in the gills; how
ever, adults from the two regions are identical. Upon comparison of Florida
nymphs with the Canadian form stated (by letter, 1939) that the Florida
species is "very close to our _P. volitans, whioh occurs all over the
Laurentian shield region of Ontario. The legs are somewhat harier and the
abdominal markings more prominent than in P. volitans..By rearing and
thus correlating nymphs and adults, Dr. Ides identification has been
fully verified.


i


72
"The cavity through which water ascends to an artesian spring is
generally a former sink in which the direction of motion of the water has
been reversed by the rise of the water table, if the w fall below the mouth of the cavity, the spring would cease to flow and would
revert to the form of a sink, provided the tubular cavity leading to the
spring does not penetrate an imprevious stratum, which might confine
the water below it under pressure," (Cooke, 1939 i 86-89),
The runs of some of the larger springs imve been discussed under larger
caloareous streams, but the majority of them are much smaller. Vegetation
is very dense just below the exit of the spring, but around the spring
itself there is nothing but bare sand. Immediately beyond the peripiiery
of the boil Ohara, hyrioghyllum, Ceratophylium, Vailisneria, Qagittaria,
Isnardia, etc, become very abundant. The surface of the vegetation close
to the spring is usually covered with a coating of caluiun carbonate de
posited from the water as the bicarbonate exposed to the air changes to
the earbonate, Oocygen is lov/, and this is reflected in the small populations
of truly aquatio insects in this regionj however, snails of the genus
Ooniobasis are exceedingly numerous on the vegetation, and mpuiiaria
occurs abundantly on the bottom sands, approximately a quarter of a mile
below the head of the springs a more abundant insect fauna become noticeable
and in this region the plants are quite free of the calcium carbonate.
The water of the springs is crystal clear cool, and definitely alkaline.


A key to the mayflies of Florida
75
Adults #
Nymphs
Stenonama
S* smithae
£* sffiS£
S# proximum *#
Hexagenla *
H. llmnophlla #.#
H# Treem ##
H. orlando .##
wp mmmmammmrnmmmmmtm
H* blllneata *
Ephemera simulans
Campsurus insertus
Oreianthus #
11 Oreianthus sp# No# lw
Siphlopleoton #
S# speoiosum
Isonychia #*
£ Perdido
I# piotipes *'
Isonyohia sp# 5 #
Isonyohia sp# 0
Blasturus #.*
B. internedius
Paraleptophlebia
76
87
100
101
123
127
138
140
151
157
162
165
169
172
173
179
180
185
189
196
198
201
202
203
215


273
at the surface for a few moments Soon, the thorax splitE and the sub
imago appears sitting quietly on the floating skin* After recovering
from the exertions necessary for its emergence, the subimago flies away
to the nearest shaded support where it remains until its life in this stage
has ended. I have noted that when partially submerged sticks were placed
in the aquarium, the nymphs tended to crawl onto them until a portion of
the thorax was above water; in this position they transformed
The following is an excerpt from my notes of February 16, 1940i
"Bphemerella trilineata female emerged at f:35 p. m just at dark. Observ
ed female nymph at surface of water about 6:25 p m She was in quieter
portion of aquarlun away from air bubbles arising from air hose Now and
then 'she would swim a short distnaoe rather vigorously and again oame to
rest. X stimulated the nymph to move, and she submerged, then swam into
the region where the water was agitated, but immediately returned to the
surface and the quiet water* When at the surface, she seemed to be strain
ing, and, while exerting an enormous foroe, her head and mesothorax would
break through the surfaoe film. She repeated the straining after each
spurt of swimming; for the most part, however, she seemed to lie quietly
at the surface At 6:36, her thorax reared almost completely out of the
water and by the count of ten, the wings were free* She did not move after
freeing her abdomen, but sat quite still, partially on the surface film
and partially on the exuviae; after two minutes, she became active again,
crawled up the side of the aquarium, rested and then flew away The elec
tric light was burining and this agitated her to some extent but after a
moment of hesitancy, she again became still."
Emergence takes place in late afternoon; in some oases in the lab-


339
C* f. minor in my collection from all months of the year*
HABITS: Callibaetis nymphs are the most graceful of all the mayfly immatures
found in Florida waters. Hanging, with the body arohed, from a plant stem,
the green insect blends almost perfectly with its background, and only the
delicate movements of the antennae and the shuttling motion of the large,
foliaceous gills draws ones eyes to the nymph. If disturbed, the insect
darts rapidly away from the disagreeable area by rapid flicks of the hairy-
caudal filaments. There is no undulatory movement suoh as used by the
Leptophlebines in their awkward swimming* The body is at a maximum of
efficiency for suoh darting actions as those of Callibaetis stream-lined
shape, hairy caudal filaments, and the ability to become motionless in an
instant. Br* Needham has beautifully described the actions of Callibaetis
nymphs; I repeat only a paragraph: "The ordinary activities of Callibaetis
nymphs may readily be seen by watching specimens in a small aquarium* Their
clambering about among water plants is strikingly intermittent: a run here,
a dash yonder, a sprint aoross the bottom, and then a sudden halt, in an
attitude of alertness, body gracefully arched, head and tail up, antennae
extended, and caudal plumes outspread* Such sudden starting and stopping
is common to the behavior of many defenceless herbivores and is well cal
culated to throw the eye of a pursurer off the track. The stopping is
so sudden, and the nymph sits so tight among the protective greens and
grays and browns of its environment, that the eye with difficulty locates
it while at rest. So it sits still for a time, lightly poised, facing an
opening between the stems, ready for another instant spring, its banded
caudal filaments gracefully arched and drooping, displayed like the plumes
in a proudly decorated roosters tail* Very slowly the antennae, long and


296
structures that they were held*
I have never witnessed the mating flight of this species but Need
ham (1908 192) reported concerning T' alleotus, "One of its favorite
swarming places was the open area above the pole bridge******* Here it
swarmed at midday filling the air like snowflakes, with dragon flies,
pnri robber flies lurking around the edges of the swarm capturing as many
specimens as they could eat*" The same author (1927 13) described the
flight of T* mi nut us (as T* explloatus) "They fly by day, the swarms being
thickest in the forenoon* The males fly highest, up to 60 feet or more,
in vertical lines, up and down incessantly* The females, after mating,
fly low over the rippled surface of the stream, each oarrying her little
bunch of eggs extended at the tip of the abdomen and ready to let fall
into the water* On sweeping the wet hand-screen thru the swarm, it was
covered at one stroke with hundreds of females and their loosened egg
masses."
First attempts to rear the nymphs in the laboratory in still water
resulted in the death of the insects within one or two days after collect
ing* After installation of an aerator, the immatures were kept for as long
as a month after oolleotion and many of these emerged*
Emergence was not observed in the fieldj in the laboratory, there
seemed to be no set time for the event to oeour* All observations were in
February during which the hour of emergence ranged fresa 9 16 A* M* to
730 P. M. with a tendenoy toward a morning predominance* The subimagal
and imagal life span were not determined, for, as mentioned above, the
subimago in every case died before molting*
DERIVATION OF THE SPECIES With so little known of the distribution of


345
nymphs); Welaka (July 5, 1939, A# M* Laessle, adults; October 23, 1939,
J, J, Friauf, adults; July 22, 1940, E L, Pierce, adults; October 19,
1940, Vi* A* McLane, adults)* St* Johns Co. (April 23, 1938, F* II* Y,,
nymphs)* Seminole Co* Big EconlocBlmtch.ee river (February 22, 1941,
1* /.right and ll* west fall, nymphs)* Sumter Co* 1 mile north of county
line (iJarch 27, 1938, L 3*, nymphs)* Suwannee Co* Suwannee river at
Branford (June 6, 1940, L* B*, adults). Taylor Co* 6*6 miles east of
Perry' (February 5, 193C, L. B*, nymphs); 7*3 miles north west of Perry
(April 1, 1938, Ii* H* H and L* J* M*, nymphs)* Volusia Co* near Benson
Springs (August 30, 1938, T* II* Hubbell and J* J* Friauf, adults); Daytona
(august 1, 1939, J. Sussell, nymphs)*
Callibaetis pretiosus Banks
TAXONOMY The taxonomic position of the Florida speoimens that I am referring
to C* pretiosus is still somewhat in doubt, but they seem to fit the descrip
tion of this species better than that of any of the other described forms.
Dr* Nathan Banks kindly presented me with two adults from Massachusetts,
and examined a Florida speoimen whioh I sent to the Museum of Comparative
Zoology for comparison with the types* He suggested that the Florida mayfly
was pretiosus, but did not give a definite identification* Further com
parison of my speoimens (females) with the northern, forms leads me to be
lieve that, at moBt, the Florida insects are of subspeoifio rank; until
adults from other localities can be examined, I consider it best to use
only a specific name*
Banks desoribed the species from Virginia in 1914; since that date,
there have been no published records of its occurrence in other regions until


392
In the north, the other species of the pygmaeus group are strictly sea
sonal; pygmaeus emerges during the summer, and maodunnoughi is known
for two dates, June 24 and July 18.
HABITSi The habits of spiethi are not essentially different frcm those of
spinosus. The food is so finely masticated that it is difficult to deter
mine its nature from a study of the oontents of the alimentary canal. Some
of the identifiable fragaents included algae, parts of diatoms, small roots,
and plant debris (probably leaf or stem epidermis).
LIFE HISTORY Life as a nymph probably occupies a period of about six
months, but since rearing was not successful and attempted artificial
fertilization gave no positive results, this must remain conjectural.
At all times of the year, nymphs of all ages oan be found in Florida waters.
Viihen the nymph is mature and ready to transform, it swims to the sur
face, suddenly, as a subimago, bursts free of the nym hal skin, and float
ing on this a moment rests, then flies away. Emergence takes place in
the slower flowing parts of the stream, where upsetting is least likely
to occur and where the insect may rest before testing its newly acquired
wings. After this short rest, the subimago rises to nearby bushes or
trees where, once settled, it remains, unless disturbed, until the ulti
mate molt takes place. The subimaginal stage lasts from seven to ten
hours, and the males may live about twenty-four hours longer.
The transformation to the subimago takes place from perhaps an hour
before sunset until the sun has completely set but darkness has not yet
fallen. The height of emergence is just after sunset, and lasts for about
fifteen minutes.
I have not observed the mating flight of spiethi, and mating flights


65
bein' almost bare, as in the type of stream mentioned above they are
covered with dense growths of Vallisneria, Sagittaria, and Potamogetn
and these plants in turn are thickly covered with algae There may be some
debris collected in the sloxver areas near shore, but in mid-stream the vege
tation is swept quite clean, although an occasional partially submerged log
may lie among the plants. These streams are usually not much more nor
less than twenty feet across and may be as much as five feet in depth at
the odnter. In their deeper parts, the vegetation tends to disappear, and
may be entirely absent from exceptionally deep stretches. The rete of flow
is moderate, but seldom strong enough to cause any marked disturbance of
the water surface. For the most part, the creeks drain scrub lands and
high pine and hammook country, and the water is much lighter in color
than that of the streams described under (1); however, the water is usually
definitely acidic, with a pH approximating 6,0. Silt deposits are not as
pronounced in these streams as in those of class (1), and debris along the
shore is likewise less in quantity,
(3) Silt-bottom creeks with little vegetations Silt-bottom streams are
rather common in the northern part of the central highlands of Florida*
The stream bottom is covered with a layer of silt overlying the sand and
varying from a few inches to several feet in depth. The rate of flow is
comparatively slower than that of the sand-bottom streams, but is is
steady and quite perceptible. The water is definitely acidic and usually
rather strongly tinted, often approaching a strong coffee color. The silt
bottom is frequently overlain by layers of leaves and strewn with much
ether debris, but there are few cr no plants in the stream proper. Near
shore Persicaria and various sedges and grasses may be present, but they


410
In 1937, Id published the descriptions of three nymphal forms in
the genus Cloeon. Now that seven speoies are known in the nymphal stage,
these may be divided into three groups on the basis of gill structure
those with double lamellae on segments 1-6 or 1-7} those with single
lamellae on all segments; and those with double lamellae on segment one
only. C rubropiotum falls into this latter group. It appears that
the Florida form would be intermediate between the two other groups, and,
in this regard, Ides data bear out this conclusion* In his northern
specimens, he has found some with double lamellae on the first segment only
and others with double lamellae on segments one and two. This indicates
that the character is still in a state of flux but apparently the tendency
is toward the adoption of the doubled gill condition. C. rubropiotum, then,
probably arose at a later time than the doubled-gilled speoies and is
evolving along the same line which they followed.
DISTRIBUTION} C. rubropiotum was described from Ontario, and sinoe has
been reoorded from Quebec, Willoughby, Ohio, and Ithaoa, New York* If the
Florida specimens are rubropiotun, the distribution is certainly peouliar
unless it be explained by lack of collecting. The speoies apparently
does not come east of the Valley and Ridge Province until it reaohes the
Coastal Plain in Florida where it is dispersed over the western region of
the state. However, nymphs are known only from a rather restricted portion
of Florida, that part in which the streams most closely resemble the con
ditions found in the Appalachians. The eastern spread of the species in
Florida may have been stopped by the wide area of dry, sandy country which
separates the Auoilla river from the Suwannee drainage. This distribution
would argue for the movement into the state along the western side of the


245
collecting in a small, sand-bottomed creek emptying into the Choctaw-
hatohee Bay, Mr. Young and I overturned a large log lying not more than
twelve feet from the salt water* The underside of this old stump was
literally covered with mayfly nymphs (the number of nymphs is not to be
compared with that occurring on the undersides of rocks of comparable
size in mountain streams) madly scrambling about* These nymphs were
mainly Choroterpes hubbelli and, more rarely, Ephemeral1a trilineata*
Since the nymph of C* basalis 6 the only described immature of
the genus, it would be fruitless to discuss the taxonomic relations of
C. hubbelli nymphs*
DISTRIBUTION! In Florida, the speoies is widely distributed, its range
extending from the northeast oorner to the west-oentral region the
western part of Duval county to the northeast part of Hillsborough county
with a greater concentration in the north-central portionj then,
skipping a broad band of counties, Chorbterpes next is found in Bay and
Walton counties* No other Florida records are known,but nymphs have
been taken in Thomas county, Georgia, just above Jefferson and Leon coun
ties in Florida* Other nymphs in my collection (species uncertain) are
from Toombs county, Georgia and Nashville, Tennessee. It is very likely
that C. hubbelli ooours in the streams between Alachua and Bay counties
even though it has not appeared in the many collections made between the
two regions*
It is probable that C. nubbelli is a Coastal Plain species occurring
throughout this region in Florida, Georgia, and Alabama wherever eoologi-
cal conditions permit* On a recent collecting trip into southern Alabama,
north, and west Florida, no specimens of Choroterpes were taken west of


387
Plateaus, and thence into the Coastal Plain. The path may conceivably
have been by way of the tributaries of the Mississippi river; from these,
it would not be difficult to picture the spread of the species into the
Mobile and Apalachicola rivers*
LOCALITY RECORDS: Alachua Co Santa Fe river at Poe Springs (May El,
1934, J* S* R, nymphs; March 24, 1937, L. £, nymphs; March 12, 1938,
L nymphs; February 18, 1939, nymphs; March 25, 1939, L. B*, nymphs;
i
October 3, 1939, L* B, adults; October 25, 1939, L* B, nymphs and
adults; March 1, 1940, L. B, nymphs; June 13, 1940, L B, nymphs)*
Oadsden Co River Junction (March 17, 1939, L. 3*, nymphs); 4 l/2
miles south of River Junction (July 1, 1939, L* J* M* and L* B, nymphs)*
Hillsborougli Co* Bell creek (March 26, 1938, L. B, nymphs); Hillsborough
river (October 21, 1940, L* J M, adults)* Jackson Co Florida Caverns
State Park (December 2, 1939, L B, nymphs) Jefferson Co. (April 1,
1938, H* H H* and L* J M., nymphs). Leon Co* 11.2 miles west of
Tallahassee (March 16, 1939, L B, nymphs). Liberty Co Sweetwater
creek (November 4, 1938, L. B, nymphs; July 1, 1939, L J* M, and L B,,
nymphs; December 1, 1939, L* B, nymphs); 10 miles south of River Junc
tion (March 17, 1939, L* B, nymphs). Sumter Co 2 miles north of
Bushnell (Marhh 27, 1938, L B., nymphs). Walton Co 1*2 miles east
of Okaloosa county lino (November 6, 1938, L B., nymphs). Washington
Co Holmes creek (July 2, 1939, L. J. M and L B, nymphs)*
Baetis spiethi Berner
TAXONOMY: Baetis spiethi is the first speoies of the pygmaeus group to
be found in the south. The insect was described from a fairly large series


bl
no little influence, ¡since great areas of the state are characterized by
swamp-like and sandy conditions and pine barrens with no development of
streams, their Epheraeropteran fauna is extremely limited. This is par
ticularly true of that portion which lies at the southern tip of the state
*
and commonly designated the Neotropical region. The mayflies found here
are not Neotropical in origin, but are true Hearctic species distributed
throughout Florida; in fact, Caenis diminuta is just as common throughout
the eastern part of much of the Hearctic as in this unique, southern,
biological area*
THE HABITATS OF FLORIDA MAYFLIES
It is generally recognized that the mayfly population of a region
is intimately related to the aquatic conditions of that region. From the
standpoints of both the ecological distribution of mayflies and physiography,
Florida can be divided into five natural areas (see map 1). The boundaries
of these areas shown on the map are rather arbitrary. The aquatic con
ditions in the ooastal lowlands overlap to a great extent those conditions
found in the other areas, but these boundaries are useful in delimiting
in a broad way the iresh water situations as they occur in Florida.
The ooastal lowlands almost everywhere lies less than one hundred feet
above sea level; the height above sea level of the other regions varies
from one hundred to about three hundred feet. The drainage of these various
subdivisions of the state is closely linked with the topography.
The ooastal lowlands is a swampy and marshy area,including, in its
southern roaches, the great expanse of the Florida Everglades, and con-


year round. Although no adults are at hand for January May, September,
and November, this is no indication of lack of emergence, but only that I
was unable to get to streams which support populations of this species;
however, there are nymphs in my collection whioh certainly would have em
erged during these months. The type specimens were collected in June and
July and indicate nothing of the seasonal life of the species farther north,
HABITS* The habits of smithae and exiguum are identical. In the field,
mature exiguum nymphs may be differentiated from smithae nymphs by the fact
that across the thorax of the former species there is a rather borad yellow
ish-brown band,
LIFE HISTORY* Life history of the species does not differ essentially
from that of S smithae except that the subimaginal period is, in general,
somewhat shorter, lasting from Seventeen to twenty hours, I have observed
no mating flights of S, ex i guien,
DERIVATION OF THE SPECIES* The collection of exiguum from the Chattahoo
chee river and the Etowah river furnishes a clear explanation of the mode
of entrance of the species into Florida, for it does not appear to have
arisen in this latter area. The tributaries of the Chattahoochee, and the
main stream as well, furnish ideal situations for the nymphs, and they ooour
commonly in the small creeks draining into the Apalachicola river, S,
exiguum may possibly have arisen from the same basic stock which gave rise
to smithae, integrum, and beHum,
LOCALITY RECORDS* Alachua Co, Santa Fe river at Pee Springs (May 14,
1934, J* S, R,, nymphs| May 21, 1934, J S# R,, nymphs; March 19, 1935,
J. S, R,# nymphs; April 15, 1935, J, S, R., nymphs; March 24, 1937, L, B,,
nymphs; March 12, 1938, L, B,, nymphs and adults; March 18, 1938, L, B,,




P. volitans
216
P* bradleyl ***<
Habrophlebiodea
II* brunnelpennls .
Choroterpes
C. hubbelll ...*
Habrophlebla *.
H* vit*1*81118
Baetlsoa
B* rogorsl
Sphemerella ***
E* trilinsata
B* apalaohloola *
E ohootawhatohee
e* hirsufca
Tricorythodes
T_* albiliaaatus
Caenis *.
C* diminuta
C. hilaris ***
Braohyoeroue *..
B* maoulatum *
B* infrequent **
Callibaetis **
C* floridanus
224
229
230
244
244
252
252
255
257
266
268
276
281
284
288
290
299
301
318
322
326
330
332
333
C* pretiosus
345


310
the development of £* diminuta from egg to adult Many difficulties
beset the rearing of the nymphs* The eggs are easily hatohed but when
food material is introduced, rotifers, flatworms, and small oligochaets
are also accidentally transferred* In most cases these other forms fur
nish too much competition for the delicate nymph.8 and many of the latter
perish. However, the four specimens mentioned above must have been
exceptionally sturdy,for several times the water almost disappeared from
the dish* There were many Protosoa in the bowl, and most of the time very
little light reached the insects (exoept artificial)*
Many nymphs have hatched; the following table gives the time from
oviposition to hatching.
OVIPOSITED
HATCHED
HUMBER OF HOURS AND DAYS
Sept* 4, 7t45 p.m.
Sept* 11
Approximately 7 days
Sept* 13, SilO p*m*
Sept* 19, 9*30-a.m,
12*40 p.m.
Approximately 135 hours; 6
days
Sept* 28, 7t30 p.m*
Oct* 3, 11*10 a*m.
7*15 p.m*
Approximately 115 hours; 5
days
Feb* 24, 6*15 p* m*
March 3, 2*00 p.m*
Approximately 164 hours; 7
days
March 18,8*00 p* m*
March 29, 9*20 p.m.
Approximately 265 hours; 11
days
April 26, 8*20 p.m*
May 6-7, 12*30 p.m*
Approximately 256 hours; 10 l/2
days
Sept. 14, 7*45 p.m*
Sept* 21, a* m*
Approximately 156 hours; 6 l/2
dayB


307
and the adult begins to crawl toward the ligh, its wings held completely
apart and in a horizontal plane, or erven depressed until they almost touch
the object on which the insect is walking* Once attracted to a light,
the adult seems almost helpless and is an easy prey for many insects, par
ticularly ants*
LIFE HISTORY* I have been fortunate in being able to rear this species
from egg to adult* Many nymphs have hatched but only two have been success- "
fully reared, all others dying during some preadult stage* The entire
period of development was approximately three hours less than one hun
dred twenty-four days* I was unable to determine the number of instars,
but some data has been obtained on growth rate, hatching,and other fea
tures of life history. These are presented in the following table and
as excerpts from my notes.
10/23/39 At 6*40 p* m* paid visit to light near University of
Florida campus [a low light surrounded by a flat slab on which many in
sects gather] and collected 15 ¥ £ diminuta* These were taken within
ten minutes even though it was still quite light and there was a bright
moon* Specimens were then separated and each was placed on the surface
of a bowl of water* oviposition was completed by 7*20 p* m* Most speci
mens voluntarily completed oviposition, but others which did not were
aided by squeezing the abdomen with forceps* The females, once placed
on the water showed no inclination to leave even after emptying the
abdomen* Eaoh dish was given a number and the female given a corresponding
number and preserved in alcohol*
10/30/39 By 7*15 all eggs in some of the bowls had hatched, in
others only a part of them, but hatohing had started in all*


431
In the Suwannee river, of which the Santa Fe is a tributary, the
nymphs must of necessity remain close to shore for the water becomes
deep very rapidly and suitable situations for the nymphs are rather rare.
The river current is fairly rapid, but the aquatic vegetation is limited
and consists for the most part of Myriophyllum and Perseoaria. Mayflies
are not common where collections were made, and since I had been warned
that many cottonmouth moocasins were in the vicinity, particularly among
the rocks where I was working, my collecting suffered as a result. How
ever, before the warning, nymphs of several species of ephemerids were
collected, among them JP. parvulian from rooks along the river margin.
Two streams from which nymphs have been taken have sand-bottoms, are
slightly acidic, and flow at a moderately swift rate. In these streams,
the nymphs were found on vegetation and on exposed roots of terrestrial
plants which projected into the water.
Associated with parvulum in the Santa Fe river are nymphs of B. spino-
sus, B. intercalaris, Pseudocloeon alachua, Centroptilum viridooularis,
C. hobbsi, Tricorythodes albilineatus, Stenonema smithae, S. proximum, S.
exlguum, and Hexagenla orlando. The Suwannee river provides an additional
associate in Isonyohia pictipes. In the Fenholloway river Paraleptophlebia
volitans sind P. bradleyi nymphs were found with parvulum, and in Sweetwater
creek Oreianthus sp. No. 1 and Caenis hilaris occurred as well as those
species found in the Santa Fe river.
SEASONS* Although collections of P. parvulum are not extensive, those at
hand indicate emergence throughout the year. In the northern reaches of
its range, the species is, of course, seasonal; Modunnough has found that
in the spring generation the individuals are larger than those of the


Ace nt re lia
S50
A* ephippiatue t.351
A. propinquua 357
Baetis * 560
B# apinosus *. 362
B australis ** 375
B. interoalarls 361
B* spiethi 387
CentroptHum 396
£ -virldocularis 397
£ hobbsl 405
Cloeon rubropiotun * 409
Cloeon nyssa 414
Pseudooloeon 418
P* alachua 420
£ panrulun 429
_P. punctiventris ... 432
P* blmaoulatus 434
References * 439
Biography-
447


429
L. J. M., L. B., nymphs); Hillsborough river (February 11, 1939, L. J.
M., nymphsj October 21, 1940, L. J. M., adults), Madison Co. 4.3
miles east of Jefferson county line (February 5, 1938, L. B., nymphs).
Marion Co. Withlacooohee river (April 2, 1937, L. B., nymphs; March
25, 1938, L. B, nymphs); Rainbow Springs run (March 9, 1940, L. B.,
adults). Taylor Co. Fenholloway river (May 29, 1940, H. H. H. and L.
B., nymphs).
Pseudooloeon parvulum McDunnough
TAXONOMY* There is some doubt concerning the identification of the Florida
specimens as Pseudooloeon parvulum. A series of nymphs closely resembles
Ida's description and drawings of the species, and a single male adult in
my collection is much like Mobunnough's description of the true P. parvulum.
The Florida specimens differ only in minor points of abdominal maoulation
from the nymphs of the northern P. parvulum; the male adult differs slightly
in color pattern, but the difference are scarcely sufficient to warrant the
erection of a new species.
MoDunnough described P, parvulum from a series of adults taken at
Tillsonburg, Ontario and from Kazubazua, Quebec. In his description, he
included the descriptions of male, female and nymph, and at the same time
indicated that the nymph of parvulum is at once distinguishable from all
others of the genus by the fact that the caudal filaments are alternately
banded with pale and dark color as in the nymphs of Stenonema. Ide (1937*
236) added the maoulation of the gills as a distinguishing feature of the
nymphs. The Florida speoimens all show very clearly, the banded caudal
filaments, the definitely maculate gills, and mouthparts which are almost


70
trie Everglades are bounded, by mangrove swamps, which separate them from the
open waters of Florida Bay and the Crulf of lxico...
"The Everglades, as the name implies, are open grassy meadows. Here
and there olumps of tree3 lend variety to the landscape....
"ine Everglades differ from most swamps ?nd boggy places in the scarcity
of trees and in their lack of ordinary mud and clay. The entire Everglades
are underlain by nard limestone, which is cushioned in the lower, generally
flooded parts by deposits of peat....* Where peat is absent, bare limestone
shows at the surface*" (Cooks, 1839t 55-66).
Since drainage ditches have been put through the Everglades, the land,
during the dry periods, beoomes very liable to burning and much of the peat
has been destroyed in the last few years* During the rainy season much of
the Everglades is covered to a depth of two or three feet by the water
which overflows from the drainage canals* When this flooding occurs, the
normal biocenoses of the canals are no longer confined to these ohannels
but spread uniformly over the inundated areas; however, the spread is thin
compared with the concentration of organisms within the canals themselves.
Only pond, swamp, aud stagnant water animals can maintain themselves in this
environment, and the mayflies associated with this region, Callibaetis
floridanus and Caenis diminuta, are typical pond and swamp inimbitants which
are found throughout Florida*
Eaw grass is the predominaht vegetation and grows profusely throughout
the marsh. 'The 'lack of shade trees allows the water to become very warm
outside the canals, but in the canals themselves it is several degrees cooler .
There is little submergent vegetation where the overflowing water has spread
over the glades, but after it has stood for some tlte algae become noticeable.


4
the great quantities of ata on mayflies that lie had aecuaulated over a
period of thirty-five years were not to be lightly set aside, and these
were brought together in 1935 in "The Biology of Mayflies," of which
Needham is senior author*
Nathan Banks, at the present time, has completely given up work on
the Ephemeroptera, Taxonomic papers were published by him in 1914, 1918,
and 1924.
71 A, Clemens, no longer working with the mayflies, has published
papers dealing with a fairly wide range of subjects* In 1913, 1915, and
1924 he dealt with taxonomy and in 1913, 1915, and 1922 principally with
life histories* His most important paper, "An Ecological Study of the
Mayfly Chirotenetes," appeared in 1917, and is a thorough and very ex>*
lightening pieoe of work. Three other papers by this author disoussed
mayflies in relation to their availability as fish food*
Ann li* lorgan in her more recent papers has treated physiologioal
problems, mainly oxygen relationships* Her first paper in 1911 was tax
onomic with some ecological discussions, and in 1913 she published "A
contribution to the Biology of Mayflies." Her two other papers dealing
with mayflies include a study of venation (1911) and a description of the
mating flight of a South American species of Campsurus (1929)*
Helen E* Murphy has contributed but a single paper dealing with North
American mayflies,and in it she describes the complete life history of
baetis vagans (1922).
G* S* bodds and F. L* Hisaw in 1924 published "Adaptations of Mayfly
Nymphs to Swift Streams," a paper which has proven to be extremely important.
The former author also published a paper on the mayflies of Colorado (1923).


315
of the ponds, puddles, ana ditches of the Coastal Plain* At any rato,
migration has not followed any particular river drainages, bub has been
quite independent o M t. XX' uj
LOCALITY RECORDS! Alachua Co, 3 miles S. W* Gainesville (April 9,
1954, H, T. Townsend, nymphs); Hogtovra Creek (Fb**uayy 15, 1937, F* IT,
Y. A L, B, nymphs; May 30, 1937, F, N* Y* & L, B, nymphs; September
25, 1937, L* B,, nymphs); 5 miles N TV* Gainesville (November 8, 1937,
L* B*, nymphs); 16 miles N, Gainesville (May 12, 1937, L, B., nymphs);
7 miles II* W, Gainesville (May 4, 1937, F, N, Y*, adult); 7 miles IT* E
Gainesville (May 11, 1937, L, B,, Nymphs); Lake Newnan (March 16, 1932;
September 20, 1938, A* F. Carr* adult; September 27, 1939, F. IT, Y,,
nymphs); Santa Fe River at Worthington Springs (September 2, 1939, L, B,,
nymphs and adults); Freezers Pond (September 25, 1937, L, B, adults;
September 29, 1937, L. B,, adults; October 5, 1939, L. B,, adults); Lake
Alice (March 17, 1937, L, B,, nymphs; November 15, 1937, L, B, adults;
February 24, 1940, L B, A J. C, Siokinson, adults); Santa Fe River at
Poe Springs (March 21, 1933, J, S R, nymphs); Gainesville (March 1,
nymphs, April 5, nymphs, May 10, nymphs, October 4, nymphs, October 8,
nymphs, October 24, nymphs all taken in 1937; April 1, adults,October
21, adults 1938; March 23, adults, March 24, adults, September 4, adults,
September 6, adults, September 13, adults, September 28, adults, October
6, adults, October 14, adults, October 23, adults, October 24, adults,
all taken in 1939; Maroh 18, nymphs and adults, March 19, adults, March
29, Adults, April 26, adults, September 14, adults, October 2, adults,
October 25, adults, all taken in 1940, The proceeding records are those
of L, B,j March 29, 1939, A N, Tissot, adults; March 24, 1939, A, N,


260
their imaginal molt. The subimagos, upon emerging, fly to the lower branches
of the marginal trees and bushes where they await the final molt.
SEASONS* The habits of emergence correspond with those of northern relatives
in that it is striotly seasonalj however, the season is somewhat extended.
Adults begin to emerge sometime early in March and continue until late sum
mer. My earliest records for mature nymphs are March 17, the latest are
two-thirds grown nymphs for the early part of June. I have collected in
many Florida streams for the nymphs of B. rogersi, but for some unknown
reason, their distribution is quite spotty. A stream from which many nymphs
were taken in March, 1938, yielded not a single one in June 1940. I have
found no situation where discovery of nymphs could be certain, and repeated
collecting from other streams where previously I had recorded them, failed
to reveal a single immature. In March, nymphs one half and two-thirds grown,
as well as last instar, were found, the younger nymphs most likely destined
to emerge sometime in middle summer. One of the most interesting records
is that of a very young nymph from early Junej very likely this is one of
the brood hatched from eggs laid during the early spring and it would pro
bably have emerged the following spring. A nymph collected at Nioeville
in November was two-thirds grown, this, obviously, was one of the spring
hatch. Adults have been reared in April and captured in June.
HABITS* Examination of food contents of the alimentary tract showed that
the immatures are vegetarians. That material which could be identified
consisted mostly of diatoms, algae, and plant epidermis. The latter was
probably obtained from leaf drift which might accumulate in the lee of peb
bles in the riffles. The predominant food seemed to be diatoms, and of these
Navioula was very oommoni the other substances were not identifiable.


36
situations -which offer refuges to the mayfly nymphs* Florida streams,
)
devoid of rooks and with much barren, sandy bottom can offer little in
comparison, even though in these streams all available habitats are utilized
Perhaps the greatest barriers to the wide dispersal of northern may
flies in Florida are the wide areas in which there are no constantly flowing
stream8* Thousands of square miles of the state, particularly in the
coastal regions, are low and flat, and the grade of the lowlands is not
sufficient to maintain permanently flowing creeks and rivers* Typioal
meotropic species cannot exist for long in standing water, and even if
a species were accidentally introduced while there was some flow, &s soon
as the flow ceased, the :.ymphs would probably die The dry, sandy scrublands
of southwest leorgia and of Florida also offer a serious barrier to less
vagile species, and this has probably helped to keep the number of mayflies
in Florida less than that of neighboring states and the northern part of
the continent. Rogers (1S33) found that the save conditions affected the
distribution of craneflies he states "one of the most important barriers
to the northern groups, the ranges of which extend into the Piedmont Province
of Georgia and the Carolinas, is the monotonous, low pine-lands of the
southern coastal pla in with their dearth of clear fairly rapid, pebble-
bottom streams*"
Comparison of Life Histories
Many differences in behavior would be expected between the mayflies
of the north and those of the south, but the most striking are found in
life histories. Those species of Ephemeroptera which are known to oocur
both in Canada and in Florida show wide variations in emergence period, and
sight in consequence be considered different physiological subspecies. In


40
seasonally limited in Florida whereas tney are definitely so in the north;
tais uas been found to be particularly true in the southern part of the
peninsula.
Reference to the accompanying temperature map (fig* 1) will show that
average temperatures in Florida are suitable, even in winter, for the adult
stage of insects which are primarily of northern origin*
There are very few Florida mayflies which are definitely seasonal and
those few are probably southern in origin, while those speoies emerging
uiroughout the year are northern forms which have immigrated into Florida*
This agrees with observations in other groups, being true not only of the
mayflies but also, in general, according to H* 2* Wallace of the Lycosid
spiders, according to C* £* dyers of tne dragonflies, aoeording to J* S*
Rogers of the crareflies, and according to I* H* aubbeil of tne Grthoptera.
This unique behavior appears to be linked with the temperature factor* It
has been shown that in the case of the mayflies the odder the water inhabited
by the immatures, the shorter the period of emergence dnce, in Florida,
the lowest winter temperature of the water is probably equal to, or slightly
l^Low, that of the nortnem waters during the summer period of emergence,
mayflies in Florida are seldom,or never, confronted with conditions which -
are unfavorable for transformation* For this reason a species (Paralepto-
phlebia volitans for example) which in Canada emerges only for about two
weeks during the summer, can emerge throughout the year in Florida* The
generalisation that species of northern origin are non-seasonal in Florida,
and that seasonal forms in this state are all of southern origin, holds good;
but this is not a complete statement of the facts* Most of the species be
lieved to be southern in origin are non-seasonal like the northern fonts


267
Traver described another nymph, tentatively placed in the needhami group,
which is intermediate in its characters between E. catawba and E# rotunda,
rotunda being a member of the invaria group.
The simplex group is one of the few taxonomic groupings in Ephemerella
about which McDunnough and Traver seem to agree. Both authors include
three species in this division, simplex, attenuata, and margarita. The
group is quite distinct in that all the nymphs possess overlapping gills
on abdominal segments four through seven only; all have well-developed
maxillary palpi} and the caudal setae show at least sparse long hairs in
their apioal portion* In 1937, Traver described another nymph of this group;
she gave it no name, but did state that it appeared to be a distinct species.
The bicolor group is one of the more highly organized, or rather
evolved groups of the genus when the nymphs are considered. This is borne
out by morphological evidence, i. e. the absence of gills from segments
two and three; the modification of the fourth pair to form elytroid gill
covers; and the rudimentary condition of the first pair. On the basis
of the nymphal structure, the bicolor group may be subdivided by use of
the condition of the occipital tubercles doris, temporalis, and tri-
lineata all have strongly developed tubercles; in the other speoies, these
structures are either moderately developed or reduced.
Ephemerella is an Holarctio genus and is widely distributed through
out the Nearotio region, from ooast to ooast and from north to south.
Very few speoies of Ephemerella have been recorded from the Coastal Plain,
and the four new Florida speoies certainly indicate that when this pro
vince is more thoroughly investigated, the genus will be found to be
quite abundant in the region.


306
HABITSi Pood of nymphs consists of plant debris, algae, and any other
organic materials! even inorganio substances may happen to be encompassed
by their raking feet* One nymph was observed feeding on a leg of a dead,
fellow nymph* When feeding, the nymphs cling with the two posterior pairs
of legs and one of the fore lege and at the same +ime extend the other
fore leg* This is then drawn in toward the mouth pulling along with it
the debris lying within reach of the claw* When the food reaohes the mouth,
the maxillary and labial palpi begin an active movement, sorting and shov
ing the food into the mouth* As soon as one leg-full of material is dis-
possed of, the other leg may reach out, or the first may again be used if
there is still material within reachj if not, the nymph moves slowly
forward until more food is encountered* Pieces of the epidermal covering of
plants are detached by the sharply pointed claws and are then pulled to
the voracious and ever anxious jaws* Feeding seems to he continuous, and
the anterior part of the alimentary tract is always well packed just as
in all other mayfly nymphs.
The adults of C* diminuta are among the most pronouncedly phototropic
of mayflies* A light set up near any body of water where they are known
to be present will attract them, males and females equally* On some nights,
I have seen almost nothing but males come to the lighting sheet, on other
nights females predominate, while on other occasions the two sexes may be
attracted in approximately equal numbers*
When most mayflies alight the wings are held vertically over the
back, but not so in Caenis* The insect alights with its wings spread
wide, leaps up again, and repeats the performance several times, eaoh
time approaching the lantern more closely* Finally, the flying is stopped


238
TRIOORYTHODES Ulmer
Until Ulmer established the genus Trieorythodes the North American
forms were included under Trioorythus* The males of species of these
two genera may be separated by the length of the fore leg, which, in the
Afrioan Trioorythus, is half the length of the bodyi in the American
Trieorythodes, it is almost, or fully, as long as the body*
McDunnough in 1931 summarised the knowledge of the North American
species of Trioorythodes, describing four, one of which was new. In 1935,
Traver limited T* explicatus (Eaton) to a Texas form and described four
additional species. In the latest work on the genus, McDunnough (1939
52-54) described another new species, and also agreed with Traver* s limita
tion of explicatus*
Concerning the distribution of this group of mayflies, LeBtage (1924
262) soys, wLe genre Trioorythus n'est connu en toute certitude que de 1*
Afrique et de Java* It nexiste pas en Europe* Lee especes nord-ameri-
caines attribuees depuis a ce genre sont des Trioorythodes Ulmer.
According to Needham and Murphy (1924*7) one species of Trieorythodes is
known from South America, its range extending from Guatemala to Argentina*
In North America, this is a widely distributed genus North Sonora, Mex-
ioo (I have reoordB from eastern Mexioo) to California to British Colum
bia to eastern Canada to Florida. Trioorythodes has never previously
been recorded south of West Virginia, nor from anywhere else east of the
Mississippi river on the Coastal Plain; however, it is common in Florida*
Very rarely has a species of Trioorythodes been treated in other
than a purely taxonomic sense* Needham and Christenson (1927*12-13) dis-


178
then it lashes out with them as though it were using the filaments for
propulsion. Walking is a slow and apparently laborious process. No
better at swimming than at walking, the nymphs would seem to be ready-
prey for most carnivores. Doubtless, their coloration and choice of
habitat act as protection against the many predators whioh infest the
streams.
Having so few specimens of 11 Oreiant hus sp No. 1*' I examined the
alimentary tract of only one nymph. The food materials, although thorough
ly macerated, appeared to consist mostly of plant epidermis with an occa
sional algal cell interspersed in the mass.
LIFE HISTORY* The above comments on the seasonal distribution of "Orei-
anthus sp. No# 1B indicate that the life history of the species occupies
approximately one year# I was unable to rear any adults in the laboratory
or to secure any in the field. Traver succeeded in rearing a few indivi
duals of 0. purpureus# Concerning the life history of this species, she
wrote (1937* 37) "As to the time of transformation from nymph to subimago,
I record my observations on those nymphs kept in the rearing cages at
Penrose. Same subimagos emerged in the forenoon, between 8 and 9:30 p.m.
One male emerged about 2:45 p# m., one female at 11 a. m. I3 it charac
teristic of the species, that the individuals emerge at such varying
times during the day?" She did not observe mating flights of the speoies#
The egg stage must be fairly long under natural conditions, for as
mentioned above, nymphs were not found in July although mature specimens
were collected in April. It is very probable that the eggs had hatched
but that the insects were so small that they passed through the meshes of
the strainer, or were overlooked#


201
Isonychia sp> G
TAXONOMY: Perhaps the two nymphs which I am calling Isonychia sp G
should be included under Isonychia sp B The two speoies differ in the
color pattern of the venter and in the presence of grayish areas in the
outer margins of each gill of Isonychia sp G These may be only local
variants of the Holmes oreek species, but until adults are reared, I believe
that the differences warrant a separation These nymphs, in common with
Isonychia sp. B, have antennae which are crossed by a brown band; the
tibial spurs are also long as would be expeoted since neither speci uen is
mature*
DISTRIBUTION: The single locality from which Isonychia sp G is known is
in Gadsden county and is one of the tributaries of the Apalaohicola river,
draining into this stream about two or three miles distant from the plaoe
where the nymphs were caught (See ?)
ECOLOGY, SEASONS, HABITS, AND LIFE HISTORY: All other data are probably
the same as that for the other Florida species of Isonychia.
DERIVATION OF THE SPECIES: Very likely the species entered Florida by way
of the Apalachicola drainage and seems to be for the most part confined to
this region, for as extensively as I have collected in northwestern Florida,
if Isonychia sp G were more widespread, it seems that it would have been
taken along with the other species of the genus It ecological valence
may be very slight, thus limiting the speoies to the drainage of the Apala
chicola river where the streams are swift, clear, and cool, and to some ex
tent resemble the waters of the more northern locales where Isonyohia nymphs
abound.
LOCALITY RECORD'S: Liberty Co. 10 miles south of River Junction (March 17,
1939, J S* R,, H d II, F N Y., L B, nymphs)


445
Steger, A* L. 1931. Some preliminar;/ notes on tho genus Ephemerelia.
Psyche. 38i 27-35, 1 text fig.
Tillyard, R. J. 1923. The wing-venation of the order Pleotoptera or mayflies.
J. Linn. Soo. London. Zool. 35j 143-182, text figs. 1-10.
Traver, J. S. 1925. Observations on the ecology of the mayfly Blasturus
cupidus. Cenad* Ent. 57j 211-218.
1931a. The Eph.em.erid genus Baetlsca. J. N* Y. Ent. Soo.
39; 45-66, plates 5-S.
1931b. A new mayfly genus fro?u Forth Carolina. Caad. Ent.
63; 103-109, plate 7.
...... 1931c. Seven new southern species of the mayfly genus Hexagenia,
with notos on the genus. Ann. Snt. ifoc. Ara. 24; 591-620, plate 1.
1932.a.Neoclooon, a new mayfly genus (Ephemerida). J. N. Y.
Snt. hoc. 40; 565-3^, plate 14.
1932-33. Mayflies of North Carolina. Jour. Elisha Mitchell
Soi. Soc. 47; 85-161, 162-236, plates 1-8j 48: 141-206, 1 plate.
1933. Heptagenlne mayflies of North America. J. N. Y. Ent.
Soo. 41; 105-125.
1934. New North American Species of mayflies. J* Elisha
Mitohell Soi. Soc. 50; 139-254, 1 plate.
1937. Notes on mayflies of the southeastern states (Ephemero-
ptera). J. Elish Mitchell Soi* Soo. S3; 27-86, 1 pi.
1938. Mayflies of Puerto Rico. J. Agrl. Uhiv. of Puerto
Rico. 22; 5-42, plates 1-3.
Ulmer, 6. 1919. Neue Ephemeropteren* Arch. Naturg. Berlin. 85 Abt.
A. 11* 1-80, figs.
1920* Trichopteren and Ephemeropteren aus Hohlen* wentshoe
snt* Zeitschr. Berlin. Pp. 303-309.
1932-33. Aquatic insects of China. Art. 6, Revised key to
the genera of Ephameroptera. Peking Nat. Hist Bull. 7 195-218,
plates 1-2.
TJp ho It, S* M. 1937. Two new mayflies frcsn the Pacific coast. Pan-Pacifio
Errb. 13: 85-88.
Walsh, B. I). 1862. List of the Pseudoneuroptera of Illinois contained in
the cabinet of the writer, with the description of over 40 new species,
nnri notes on their structural affinities. Proo. Aoad. Nat. Soi. Phila.
2nd ser. Pp. 361-402.


249
negatively phototropic and strongly thigmotactic in the nymphal stage,
but the adult, particularly during the subimagal stage, shows a strong
positive reaction to light This phototactic response lias frequently been
demonstrated in the laboratory
Food materials are much the same as those utilized by Habrophlebiodes
brunneipennis, i. e# plant materials and probably some protozoans* When
nymphs are kept in an aquarium with only dead leaves, they seem to grow
perfectly well on a diet of scrapings from the surface of these leaves,
and have been kept alive almost two months on such food.
Body movements of nymphs are similar to those of Habrophlebiodes, but
the nymphs are easily distinguished from other genera by the fact that the
gills are not spread when the insect is submerged they are held above
and close to the abdomen where they are frequently vibrated
LIFE HIST OR: Nymphal data indicate that underwater life may occupy a
period of from six to eight months So few adults were reared that the
length of life of the imago was not determined, but it appears likely
that death will take place within fifteen to twenty-four hours after the
final molt. Transformation in the laboratory has never occurred before
7:00 p. m. (after dark) and has taken place as late as 9:30 p m*
When the subimago is ready to emerge, the nym h swims about vigorously
much like Blasturus; however, it does not crawl from the water (very little
opportunity was provided for this), but bursts free at the surface, floats
for a moment on the exuviae as a subimago, and then flies to a nearby sup
port. Transformation is over in a few seconds, the whole process (after
the swimming movements have been completed) occupies no more than thirty
Once emergence has taken place, the subimago sits complacently awaiting the


223
1939, L. B.t adults; June 24, 1939, L. B., adults); 2 1/2 miles west
of Gainesville (January 16, 1938, L. B*, nymphs; March 5, 1938, L. B.,
nymphs and adults; January 7, 1939, L. B., adults; January 14, 1939,
L. B., adults; January 28, 1939, L. B., adults; March 10, 1939, L. B.,
adults; April 21, 1939, L. B., adults; October 6, 1939, L. B., adults;
November 11, 1939, L. B., adults; February 5, 1939, L. B., adults;
March 19, 1940, L# B., adults). Bay Co. 5.6 miles north of Panama
City (May 30, 1940, H. H. II. and L. B., nymphs); 27.4 miles north of
St. Andrews (May 30, 1940, H. H. H. and L. B, nymphs); Pine Log Creek
(May 31, 1940, H. H H*, and L. B, nymphs). Columbia Co. Falling
Creek (November 13, 1938, W. M. McLane and L* B., nymphs and adults).
Hamilton Co. 8.3 miles south of Jasper (February 4, 1938, L. B.,
nymphs). Holmes Co. Sandy Creek (December 14, 1939, L. B*, nymphs).
Jackson Co* 3.6 miles north of Altha (December 10, 1937, L. B., nymphs;
June 9, 1938, L. B., adults). Jefferson Co. (April 1, 1938, H. H. H.
and L. J. M., nymphs). Leon Co* 7 miles south of Hwy. $ 127 on # 19
(June 5, 1938, L. B., nymphs). Liberty Co. Sweetwater Creek (July
1, 1939, L. J. M. and L. B., nymphs); 10 miles south of River Junction
(Maroh 10, 1939, J. S. R., H* H. Ii,, F. N. Y., L. B., nymphs); Hosford
(March 17, 1939, L. B., nymphs). Nassau Co. 19.1 miles north of Duval
Co. line (August 28, 1938, H. E. H., nymphs). Okaloosa Co. 2 miles
east of Crestview (December 12, 1937, L. B., nymphs). Santa Rosa Co.
Pace (June 1, 1940, L. B., adults); 2 miles west of Milton (April 4,
1938, H. H* H* and L. J. M., adults). Yfalton Co. 5.4 miles east of
Freeport (April 2, 1938, H. H* H. and L. J. M., adults); 13.8 miles west
of Freeport (June 7, 1938, L. B., nymphs); 15.8 miles west of Ebro (June


243
north of Tallahassee (March 18, 1939, J* S* R., H. H# H*, F* N* Y* and
L. B., nymphs); 13 miles west of Tallahassee (November 30, 1939, H. H* H*
and L. B., nymphs)0 Liberty Co* Sweetwater Creek (June 10, 1938, L. B*,
nymphs). Santa Rosa Co.* 7.1 miles west of Milton (April 4, 1938, H. H.
H. and L* J* M*, nymphs)* Wakulla Co* - Smith Creek (June 5, 1938, L. B*,
nymphs). Walton Co* 7*3 miles west of Ebro (June 7, 1938, L. B.,
nymphs); 6.4 miles east of Freeport (April 2, 1938, H. H. H* and L, J, M.,
adults); 13*8 miles west of Freeport (June 7, 1938, L. B., nymphs);
10.6 miles west of Washington county line (May 31, 1940, H* H* H* and
L. B., nymphs); 2*1 miles west of Yfashington county line (May 31, 1940,
H* H* H. and L* Be, nymphs)*


398
of C. viridocularis leads me to associate the latter with C. convexum,
C. co^turbatum, or C. r uf o st ri gat uta However, on the basis of Traver's
drawings of genitalia, the relationships would seem to lie with C* rufo
strigatum or C* fragile. Since both wings and genitalia are similar to
those of C. rufostrigatum, these two species may possibly be the most closely
related." (Berner, 1940cs 39).
*
DISTRIBUTION* The nymphs of this species, for some unknown reason, are
very difficult to find, but the few specimens in my oolle ction indicate
that its distribution over Florida is wide; it occurs in all parts of
IV
Florida where there are permanently flowing streams. Specimens have been
taken in Hillsborough and Alachua counties and from the Suwannee river,
as well as from a band of counties in west Florida, the range extending
even into Baldwin county, Alabama. This is the only named speoies of
Centroptilum known from the Coastal Plain. (See /*>/> J v'
ECOLOGY* The nymphs of C. viridocularis prefer moderately swift streams,
the size of the ohannel seemingly being of no consequence. Many hours
have been spent searching for nymphs of this speoies in atchet creek, near
Gainesville. A day on which two or three immatures vrere found was consider
ed a great success, yet, examination of the stomach contents of several
small bass (Huro salmoides) revealed that C. viridooularis was their most
choice food, and each fish had fifteen to twenty-five nymphs in its stomach.
After discovering this, I ooliected diligently in the place from whioh the
bass were seined, but without success. This was followed by an examination
of all other conceivable habitats, but still no more than two nymphs could
be found. More recently, collections from a much smaller stream near
Gainesville have yielded proportionately many more nymphs than has Hatchet


340
slender* and so transparent as to be well nigh invisible* are sot swinging
up and down* They are moved alternately, one being lowered while the other
is lifted,
When the nymphs are collected and placed in a white enameled pan, the
water drained away, and an attempt made to lift them, they hop about very
much as small minnows* This action is particularly evident in larger nymphs,
those in the penultimate or last instar* Frequently the nymphs can be de
tected in the pan only by draining the water away from them and watching for
the kicking and hopping as they attempt to get back into the water*
Examination of the contents of the alimentary traot of nymphs showed
that they feed predominantly on algae of the filamentous type, but plant

material of other sorts was present* The nymphs graze on the algae covering
the plant stems and leaves in the ponds and ditches* rather than moving into
algal mats which sometimes form in these places* The algae most commonly
found in the enteron included Ulothrlx* Mougetia* and Oedogonium*
LIFE HISTORY? I have been unable to secure females at the time of copulation,
and have been unable to find any which had mated and which were ready to ovi
posit. Needham reported that Calllbaetis nymphs develop in from five to six
weeks from the laying of the egg* I believe that this statement is probably
based more on estimate than n actual rearing,for many species in this genus
are ovoviviparous and the nymph develops in the body of its mother for
nearly one week. There is some rather interesting information at hand con
cerning the rate of development of C* _£ minor in the Gainesville region.
Mr* J. C. Dickinson, while Investigating the rate of regeneration of life
in intermittent ponds, discovered that within five to six weeks after the
first water appeared in the ponds, mature Callibaetis nymphs could be found*


'V

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ALpfcm erefju tn
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y V \
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177
not a single specimen could be found. In March, 1939, I again collected
a number of nymphs from this creek, but in July of the same year no nymphs
were taken; in early December of 1939 half-grown nymphs were found to be
as plentiful as on any other occasion. In June, 1940, no specimens could
be found in a stream in Gadsden county where, in Maroh of the previous
year, immatures had been collected.
A study of some fifty nymphs from Florida streams substantiates the
evidence offered above. Those taken in November and December are of a
size which shows that subimagos would certainly not have emerged sooner
than the following March or April. ImmatureB taken in March were well
grown or would have matured within a month or so. "Qreianthue sp. No. 1"
thus presents one of the most restricted seasonal ranges of any mayfly
found in Florida. This fact, as has been pointed out on page is in
accord with other evidence suggesting a southern origin for the speoies.
As was there indicated, northern species are non-seasonal in Florida while
southern forms tend to have definite emergence periods.
HABITS; The nymphs swim but little, and when they do their motions are
extremely awkward. The tails are bent over the abdomen and suddenly lash
ed so that the movement of the abdomen, assisted by the beating of the al
most bare caudal filaments drives the insect slowly and with much difficulty
through the water.
The attitude of the nymphB when taken from the water is much the
same as that characterizing all of those species of mayflies which have
operoulate gill covers. A slow, deliberate movement is coupled with an
occasional flicking motion of the caudal filaments as the insect brings
thorn completely back over its dorsum until they point anteriorly, and


213
hours or less.
DERIVATION OF THE SPECIE;.;: Blasturus intermedius and B* granis are
probably derived from the same basic stock, but the relative primitiveness
of B. intermedius in the genus is unknown. It is quite possible that
this species arose from a continental stock and migrated into Florida
as the land rose and water began to flow over it surface. Blasturus
is primarily a northern genus and it seems likely that it has only re
cently come into the state. There is no evidence of endemism in the
genus*
LOCALITY RECORDS Alachua Co. 1 mile west of Lake Newnan (January
8, 1938, L. B., nymphs); 3 miles north of Paradise (February 12, 1938,
G. VanHyning, nymphs); Santa Fe River at Worthington Springs (February
12, 1938, J. M. Martin, nymphs; February 5, 1939, L. B., nymphs);
Hatchet Creek (February 8, 1938, George Van Efyning, nymphs and adults;
Februay 26, 1938, L. B*, adults; Maroh 23, 1938, L. 3., nymphs and adults;
April 2, 1938, L. B., adults)# 2 l/2 miles west of Gainesville (January
29, 1938, F* N. Y* and L. B*, nymphs; February 3, 1938, L. B, nymphs and
adults; January 7, 1939, L. B*, adults and nymphs; January 28, 1938,
L. B., nymphs and adults, images reared on January 29 and February 22;
February 5, 1940, L. B., nympha and adults, adults reared February 6, 7,
8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26,
27, 29, March 1, 3, 4, 6, 10). Columbia Co. Falling Creek (February
4, 1938, L. B., nymphs). Gadsden Co. River Junction (March 17, 1939,
J. S. R., H. H. H., F. N. Y., L. B., nymphs); 4 l/2 miles south of River
Junction (March 17, 1939, J. S. R., H. H. H., F. N. Y,, L. B., nymphs).
Holmes Col Sandy Creek (Deoember 11, 1937, L. B., nymphs). Hamilton


34
tion (for which no explanation is at present forthcoming) that the smallest
mayflies are, on the whole, the most widely disseminated a generaliza
tion that seems to be world-wide in application
Fifteen species hitherto unknown are here recorded from the state, but
nine of them are known only fresa the nynphal stage. In addition, four
new Florida speoies have recently been described making a total of nineteen
species discovered during the course of this investigation. The total faunal
list of forty-seven species from the state seams large for such a small arid
(from the standpoint of mayflies) ecologically limited region.
Actually, Florida is poor in number of species compared to those areas
which can boast of mountainous, hilly, and coastal regions all within
relatively small boundaries. Traver, investigating the mayflies of North
Carolina, found more than one hundred different species in the state, but
her collections included specimens from three physiographic provinces*
Ide (1935) working in Ontario found fifty-five speoies in on stream, and
I have been informed that subsequently he has taken more than one hundred
species from a single stream. No suph concentrations of species are found
in any Florida stream; conditions do not compare in favorability, in these
streams, for mayflies with the rapid, rocky, and well-aerated streams of
Ontario. In our most populous streams the maximum number of species found
is only nineteen, and even this is exceptional (Sweetwater Creek, Liberty
county).
In summary, it appears that the Floridian Ephemeropteran fauna is
mostly of southern origin; however, there are certain northern elements
which have entered the region and which have there succeeded remarkably well.


262
would a mature nymph which was ready to transform* On March 29, from the
same group of nymphs, another individual was found out of the water, lying
on its back on the floor of the oage I righted the nymph and it immediately
crawled toward the cloth and started climbing* It fell to the floor, but
again began moving* For two hours, the nymph showed signs of life even
though it was out of water all this time* The insect was unable to emerge*
The nymphal habits of this unique genus have been but little studied,
and have been disousaed only by Walsh and Traver* On of the interesting
statements of the former author which has later proved to be erroneous con
cerns the respiration of the nymphs: "When they were taken out of the water
the tip of the notal shield generally after a few seconds gaped apart from
the fifth dorsal joint of the abdomen, and the palpitation and structure
of the branchiae became plainly visible under the shield* The reason is
obvious* They were then compelled to breathe through their spiracles, instead
of through their branchiae* It is now known that the nymphs of mayflies
do not have open spiracles, and that the only method of respiration is by
diffusion of gaseous matter through the thin membrane of the gills* In
this connection, it might be mentioned that in Baetisoa nymphs, all of the
gills are completely covered by the mesonotal shield* I have observed that
the shield is raised almost rhythmically and the sixth pair of gills pro
jected from below the median posterior tubercle to form a tube; at the same
time, a ourrent of water is led under the huge oover to aerate the more
anterior branchiae* The last pair of gills is quite different from the other
four pairs in that each consists merely of a curled plate fitted into the
median prominence of the sixth tergite in such a way that the two gills
produce a neatly formed tube which opens anteriorly a short distance under


35
Comparative abundance
In Florida the actual number of individual mayflies that are pre
sent in a given situation is smaller than that found in northern streams*
This faot finds a partial explanation in the relatively small number of
suitable mayfly habitats in any particular stream; however, there is a
difference in abundanoe even in corresponding situations* I have examined
mountain crooks in the southern part of North Carolina, and on the undersides
of roces the number of mayflies found greatly exceeded the number 'which
might be found in analogous situations in Florida* It is necessary to
employ the tena "analogous situations" because in Florida the rook habitats
are only rarely present, and the insects use as substitutes submerged logs,
boards, etc*
In the smaller rivers and streams descending from the mountains along
the east cqast of Mexico, the number of individual insects on a single
rock is amazing* Nearly two hundred mayflies were taken from one rocls^
approximately 15 x 15 x 8 inches, and one the same rock the caddisfly oases
and blaokfly larvae literally covered the surface* Ihen a Florif tre-r-
is compared with such a river, it can be seen that, even though mayflies
are the predominant inseots, they are so much less abundant that they can
in no wise be as important in food chains as those of the rooty streams
of the north and of Mexico*
Adults of the great majority of Florida species emerge throughout the
year, and for this reason there are no great swarms (except in some of the
burrowing forms). The flights are small, composed of Inconspicuous Insects
which gather in groups to mate* The literature indicates that many of the
small northern forms collect in very large swarms to carry on their mating


XT
edit
j if ere- *cin+.
-J ,. mti


64
other aquatic vegetation .... The permanent water is usually filled with
submerged, floating, and emergent aquatic plants and may support extensive
floating mats of green algae." (Sogers, 1933)* The vegetation includes
many true aqu&tios such as Pontederia, Utricularia, Persicaria, Slobifera,
lypha, eto. as well as Hydrocotyl, maiden-oana (Juncus), and other semi-
aquatios. Many of the ponds have coverings of Castalia, and seme support
Nymphaea, bub very few are covered with water hyaointhe* Plants are not
confined to a shore zone, as in the sink-hole ponds, but may extend much
further out and in some instances may completely penetrate the ponds.
The bottom of the fluctuating pond6 is mucisy, but the layer of silt is not
deep* The water is subject to rapid changes in temperature and is much
influenced by external weather conditions. There is normally a slight tint
to the water and it is usually acidic.
(5) Temporary woods pondst These ponds are foxmed in depressions in ham
mocks and are of a more or less temporary nature; however, the vegetation
present is such as to indicate its habitual occupation of the depression*
In these ponds and around their margins are frequently found black-gum
(ifyasa biflora), button bush (Cophalanthus occidentalis), willow (Salix
ni ;er), bladderworts (Utricularia sp*), etc*, and if the water remains
for a sufficient length of time other more succulent vegetation will beoome
established* niter the water has been standing in the depression long
enough to allow growths of algae, many of the usual pond animals begin to
migrate to and become established in the pond*
(4) Sporadic ponds: The sporadic ponds are of a rather temporary nature,
and during the dry seasons may completely disappear not to reappear for
some time, perhaps they may even disappear permanently* If they remain for


at the surface of the water, suddenly the thoracic skin splits and the
subixaago appears The actual emergence takes only a few seconds. With al
most no rest, the insect arises and flics upward until out of sight (unless
some support is nearby), the flight never being horizontal but always
upward at a moderate incline. .After twenty to twenty-four hours, the ima-
ginal molt occurs. Female images may live in the laboratory as long as
three days after emergence, male adults live for about two and one-half
days.
*ayfly nymphs, immediately after molting,are very pale, almost white,
molting was observed in smithae nymphs at 1:45 p. m. (conditions in the
field might well alter the results), at 4:00 p, m. melanization had occurred
to such a great extent that the nymph was almost its normal color* By
5:30 p. m. the normal coloration had been reached.
jo. interesting point concern ng the eyes was noted in Btenonema smithae.
In mating males, i. e. those talon during a mating flight, the eyes are
black. Laboratory reared males kept in the dark will have black eyes,
yet when they are exposed to the light for a short while, the eyes become
pale, but this thange is gradual and, in laboratory reared insects, may
take as long as forty minutes.
bhllTVM'ICK OF THIS SPECIES: If S. smithae arose in the Alabama portion of
the Coastal Plain, the entrance of the species into Florida would present
no difficulties. The distribution of integrum, one of the close relatives
of smithae, is such that a conclusion of this nature would not seem to be
incorrect, for it is known from northern Georgia. The two species, and
probably be 11 urn, nay have arisen from a common stock which has subsequently
changed into one of these three species or a related form* It is rather


160
SIPHLOPLECTON Clemens
Siphlurus flexus was desoribed by Clemens in 1913 but by 1915 he
concluded that the species was sufficiently distinctive to be placed in
a separate genus, Siphlopleoton, which he erected for its reception Mo-
Dunnough (1923s 47), after examining material of the Siphlonurus group,
suggested that flexus was synonymous with basale,and this latter species
therefore became the type for the genus He again mentioned the synonymy
of the above two species in 1924, and in both papers considered Siphlo
pleoton to be one of the Heptageninae. Ide (1930s 227-228) followed
McDunnoughs placement of the genus in this subfamily Ulmer (1933s
209-211) treated the Siphlonurus group as a family, Siphlonuridae, and
included this family under the suborder Keptage nioidea) however, he com
pletely ignored Siphloplecton in his key, Spieth (1933s327) reversed the
order and considered Siphlonuroidea as the superfamily and Siphlonuridae
as a family, and under this superfamily he also included the Heptageniidae.
Still further complexities as regards the higher categories were introduced
when Traver (1932s 111) published her paper on the "Mayflies of North
Carolina" and considered Siphloplecton to be one of the Baetinae She
retained this viewpoint in 1935 when she placed Siphlopleoton as a Baetidae,
but placed the genus in the subfamily Metretopinae. The reasons of the
last author for her placement are as followss "This subfamily might well
be plaoed in the Heptageniidae, if venation and genitalia only are con
sidered Since, however, the basal joint of the tarsus is not wholly free,
but more or less fused with the bibia as in the Siphlonurinae, and the
known nymphs are distinctly of the Siphlonurine type, it may equally well


416
of an hydrophytic tree (iiyssa sp.) which on the downstream side has a small
amount of vegetation (Perseoaria sp.) growing in the sand and silt covering
the roots. Intermingled in this mass, there is an accumulation of leaf
drift, silt and other trash. By collecting thoroughly in this material, in
fact until the debfis was so stirred up that mayflies could only be caught
or lost in the current, three Cloeon nymphs were taken. Behind this stump
the water was about two feet deep and there was no perceptible flow. The
single nymph from the Chipla crainage was collected from either the vege
tation near the shore, or the leaf drift which had accumulated in this zone.
Both streams from which nymphs were taken are definitely acidlo and
are derived from strongly tinted swamp waters. The mayfly associates be
hind the stump in Holmes creek were Baetis spinosus, Caenis hilaris, Tri-
corythodes albilinoatu3, Baetis spiethi, hexagenia weewa, and Cloeon rubro-
pjotum. In the second creek, Ctenonena smithae, Blasturus intermedius,
Caenis sp., Hexagenia weewa, habrophlebiodes brunneipennis, and llabrophlebia
vibrans were found in the same region from which Cloeon nyssa was collected.
SEASONSi Four specimens taken on only two different dates would hardly
indioate the seasonal distribution of a species, however, in this case,
the data are such tat they lead me to believe that emergence oooure during
all months of the year, mature nymphs rare taken in July and a nymph in
the penultimate instar was collected in December. Cloeon rubropiotum emerges
throughout the year and there is no apparent reason wny C. nyssa should not
do the same; the above evidence seem to bear out this conclusion.
DhEIVATIOU OF THE BPECIEb: To all appearances, C. nyssa was not derived
from a southern Cloeon stock. It is probable that entrance into Florida
has been parallel to that of C* rubropiotum; passing south and west of the


Tuscaloosa The description included that of the male, female,and
nymph 1 have found that the Florida insects agree fairly well with the
description except that, in the adults, there is an orange coloration on
the vertex in the majority of specimens Traver failed to mention the
condition of tlie mouthparts of the nymphs, but it has been found that
the structure of the maxillae is one of the most important characters for
separation of S, smithae and S, exiguum nymphs. Adult S* smithae are easily
distinguished by the presence of stignatic spots, by the shape of the
male genitalia, by the pattern of oross veins in the fore wings, and by
the body coloration.
The species falls clearly into the pulohellum-tripunctatum group
of Stenonema and is quite remote from any resemblence to the interpmiota-
tum group. The penes are strongly L-shaped and there is no bar formed
in the fore wing,
Traver considers smithae to be superficially similar te S integrum,
but from descriptions it also seems to be somewhat close to bellum; how
ever, since I have seen no specimens of the latter species and only few of
the former no further comments can be added. This whole complex of species
forms a rather compact group, differing from each other only in minor
structural and ornamental characters.
DISTRIBUTIONS Since the description of smithae, the species has not been
mentioned in print, and its only published locality record is at Spencers
Mill, Tuscaloosa, Alabama. S* smithae has been found to be one of the com
monest in Florida, but it does not seen to be distributed south of Alachua
county; westwards, however, almost every flowing body of water supports
populations of nymphs and consequently smithae has been taken as far west


237
from my field notes*
Sand-bottom creek about two and one-half miles west of G-ainesville
on Newberry road, March 17, 1940. Walking downstream at 2:15 p. m. and
sighted small inserts flying about six inches abare water. Captured five
and found them to be H. brunneipennis, all males. They were flying in
an area cleared of vegetation and bathed in sunlight. Noted two separate
swarms both small, five or six members in each, but after sweeping net,
reduced to two individuals. These two flew continuously for ten minutes,
when two bther males joined them. Two females flew into the swarm and
began rising and falling with the males. The latter then approached from
below and as soon as coupled the pair flew to shore and were lost in the
shadows. Twenty minutes later the third male paired. Within a few min
utes another male joined the remaining one. These flew in unison and then
the first male approached the new arrival (<$ or ? ?) to assume the copula-
tory position, but seemed to be repulsed for the two immediately separated
and began flying in unison again. Qnoe more copulation was attempted,
the attempt lasting not more than two or three seconds. The new arrival
finally withdrew. After fifty minutes, another individual approached the
remaining male and coupled with him. The two flew slowly toward shore
and after about ten seoonds parted, the male returning to midstream, the
other mayfly became lost in shadows. After exactly one hour (from the time
observation was begun), the male ceased its flight. It seems extraordinary
that a small insect such as this can continue flight without respite
for one hour (it may possibly be that this individual flew only thirty
minutes and exchanged places with one of those which had flown into the
mating area).


553
reflected in the number of nymphs present, for there are far fewer inseots
per oubio foot of area than in the streams first desoribed*
In Alachua county, the nymphs and adults have been taken only from
Hatohet Creek, probably the best mayfly stream in oenbral Florida, In the
shallower parts of the creek there are dense growths of Potamogetn, Fon-
tanalis, and other plants among which the nymphs live. They seldom venture
into the quieter waters nearer shore where the kindred nymph, B. spinosus,
is often found* Even the more rapid water of this stream is fairly slow
when compared to the more northern streams, but the flow is continuous and
the ourrent is quite noticeable, particularly in the shallower portions.
Subiraagos only are known from the Hillsborough riverj they were collect
ed where it is fairly shallow, rapid, and filled with vegetation, principally
Vallisneria
Every stream from which I have collected nymphs of A, ephippiatus and
at which the pH was taken showed a definite acidio reaction. In no case
did the acidity range below 5.8 nor above 6.5i all reading were by the
oolorimetrio method. The Hillsborough river from which I have adults only
is slightly basic. The acidic streams drain flatwoods or swampy areas and
for the most part were slightly to strongly tinted.
Ephemeropteran nymphs found to be associated with A. ephippiatus are
Ephemerella apalaohicola, Pseudooloeon bimaculatus, _P alachua, Baetis spiethi,
B* spinosus, Paraleptophlebia volitans, Tricorythodes albillneatus, Stenonema
exiguum, S. smithae, S. proximum, Cloeon rubropiotum, Blasfcurus inteimedlus,
Habrophlebiodes brunneipennls, Choroterpes hubbelli, Hexagenia weewa, Baetisca
rogerai, Baetis australis, Ephemerella ohootawhatohee, E. trilineata, Caenis
hilaris. CentroptHum viridooularis, and Isonychia sp.


402
not evident, and the shape of the head is quite different from that of
many of the other genera of the Baetinae. It has a rather abrupt frontal
margin giving the nymph the appearance of having pulled the lower part
of its head in close to the sternum; the frontal margin is much more
rounded in Baetls. Finally, the body of CexitroptHum is shorter and thicker
than that of Baetls
The species Is rather adept in swimming and performs the act by rapid
flicks of the abdomen with the tails held stiffly out from the body; how
ever, the movement is slower than that of the more efficiently swimming
Baetls
Ydien placed in a white enamel pan without water, the nymphs, in common
with the other Baetinae, usually fall onto their sides where they remain
helpless. If stimulated, they begin to hop about by flipping the abdomen
muoh as a small minnow, but with much less strength than the latter. The
older and more rounded the nymph, the more helpless he becomes in such a
situation; the young nymphs frequently, because of their more flattened
bodies, fall with dorsal side up and are then able to crawl about*
In feeding, the nymphs do not often use the legs for bringing food
to the mouth, but put the entire burden on the mouthparts. As the nymphs
come upon food material, the head is moved into a position best suited
for seizing the food which is then taken into the mouth by means of the
maxillary palpi as they shuttle rapidly inward and outward. The food is
made up of plant materials of various sorts, principally epidermis, algae,
and,to a slight extent, diatoms.
LIFE HISTOBYs The length of nymphal life 1ms not been determined but it
probably extends over a period of six to nine months. Emergence of the
subimago occurs in late afternoon during the summer, just before ar at


228
MBITS? Nymphs have not Been observed, except superficially, in the
field. Since my collecting trips to distant localities have been merely
short excursions to a stream rather then a thorough working of the situa
tion, very little has been learned about P. bradleyi. The movements of
the body are typically Leptophlebine.
LIFE HISTORY Nothing definite is known of the life history, but an
estimate of the length of the life cyole,based on nympha1 data at hand,
of approximately twelve months does not appear unreasonable. Nymphal
history, emergence, and adulthood of related species have been discussed,
and bradleyi does not depart much from them in such activities.
DERIVATION OF THE SPECIES: A epeoies so distinct and living in the type
of environment as that of bradleyi adds difficulty to hypotheses concern
ing its origin. Very likely, the species throughout its history has
occupied only the Coastal Plain,and its presence in the southeastern part
of this province may indioate that this is its place of origin; however,
another 6ide of the story is offered if we consider it to be a reliot
species. Then, its place of origin must remain a more complete mystery.
It appears that the distribution of bradleyi may be closely tied up with
the Suwannee river drainage system, and, if origin did not occur in Florida,
this river has been used as a means of ingress.
LOCALITY RECORDS* Alachua Co. Hatchet Creek (February 8, 1338, L. B.,
adult). Columbia Co. Falling Creek (February 4, 1938, L. E., nymphs;
November 13, 1938, L. B., nymphs); 11.5 miles north of Lake City (October
27, 1938, H. H. H. and F. F* Y., nymphs). Hamilton Co* .6 miles north
of Live Oak road at U. 8. Hwy.#; 41 (February 4, 1938, L. B., nymphs and
adults). Taylor Co. Fenholloway River (November 30, 1839, L. B., nymphs).


62
there may be deeper holes such as that found in Late Mize, discussed
by Harineas (1941), which over a very small area reaches a depth of
nearly eighty feet. In the shallower portions the bottom is sandy and
covered with patchy growths of Utrloularia. There are only small deposits
of silt in the shallower zones, but in the very deepest parts the bottom
may be thickly covered with black, dense silt, in which practically
anaerobic conditions exist and in which living organisms are almost
entirely absent* The water varies from odorless to a strong tea color,
depending on the type of region drained by the pond* Many of the ponds
are rather turbid, and this turbidity combined with strongly tinged
water allows little penetration of light to the deeper parts. The water
varies in reaction from pond to pond, being acidic, circumneutral, or
slightly basio*
(b) Sink-hole ponds with the surface covered with vegetation: There
are two principal varieties of this pond type (l) those covered with
water hyacinths (fiaropus crassipes); (2) those covered with duckweed
(Lemna minor), mud-marys (Bruneria punctata), Azolla carolinlana,
Salvinia aurloulata, etc*
The first variety of pond may have a marginal ring of open water
with t he water hyacinths concentrated over most of the remaining area,
or the entire surface may be covered with these plants* If there is some
open water, submergent vegetation may take root and beoame fairly well
established, but for the most part the water hyacinths are the only
plants of any importance in the ponds* The duckweed covered ponds
seldom have any submergent vegetation growing in them, for the entire
surface is oovered with a single layer of these plants outting o^f


363
North American Baetis species" However* when the nymphb of spinosus
are compared with those of B australis* the two seem almost identical
structurally. The only means that I have found for distinguishing between
them is by the slightly longer caudal filaments and the more or less uni-
oolorous dorsum in last instar, male nymphs of australis Neither of these
characters are good criteria for separating the species when only one or a
few nymphs are involved! if a series is examined, the immatures can usually
be divided into two distinct groups*
According to McDunnough, B spinosus is allied to frondalis McD and
in general appearance is close to dardanus McD In Florida, australis is
the only species whioh appears to be olosely related to spinosus
B spinosus is one of the more advanced speoies of Baetis, for in this
species there are only two longitudinal veins in the hind wings and the
costal process is reduoed to a small hump Judged by the genitalia, its
phylogenetic relationship is not so clear, for these organs are distinctive,
particularly the forceps, which possess a very prominent tubercle at the
juncture of the second and third segments
DISTRIBUIION: Apparently Baetis spinosus is distributed over the entire
eastern portion of the United States and part of Canada, ranging from
Manitoba to south-central Florida However, until specimens are oollected
in the intervening areas, the extent of the distribution must remain in
question In Florida, B spinosus is the most widely dispersed of all
mayflies It ranges from the southwestern border of Alabama to the north
east corner of Florida, and from this latter looality as far south as
Hillsborough county. In the panhandle of Florida, B spinosus nymphs oan
be found in every stream in whoh there is permanently flowing water, and


119
difficult to conceive of smithae arising in Florida, and 11 indications are
that the presence of Smithae in the area must be explained by ironigration
LOCALITY BECORBSj Alachua Co Santa Fe river at Poe Springs (May 21,
1934, J S R, nymphs; February 24, 1937, L B, nymphs; March 12, 1938,
L. nymphs; ¡arch 25, 1939, L. B* nymphs and adults; April S, 1940,
L ., nymphs and adults); Hatchet Creek (March 22, 1937, L 3, nymphs;
February 8, 1935, L. D, nymphs; March 23, 1938, L. B, nymphs and adults;
pril 2, 1938, L £, nymphs and adults; April 18, 1938, L. B, adults;
..lay 5, 1938, L. B, nymphs and adults; November 13, 1938, L. B, adults;
March 22, 1939, L. B, nymphs and adults; April 1, 1939, L. B., adults;
April 13, 1939, L. B*, nymphs and adults; May 5, 1939, L 3, nymphs and
adults; June 24, 1939, L# B, adults; October 11, 1939, L B, nymphs and
adults; October 28, 1939, L. B., nymphs); 2 l/2 miles tost of Cainesville
(January 13, 1936, L. 3, adults and nymphs; January 29, 1933, L* B*, nymphs
and adults; February 3, 1938, L. 5, nymphs and adults; March. 5, 1933,
L* B, nymphs; January 7, 1939, L. B, nymphs; January 2S, 1939, L. B,
adults; March 10, 1939, L B., nymphs and adults; April 21, 1939, L 3,
adults; October 8, 1939, L B, nymphs and adults; January 3, 1940, L B,
adults and nymphs; March 18, 1940, L. B, nymphs and adults; May 7, 1940,
L* Id, adults and nymphs); Hogtovm creek (February 2, 1932, nymphs; March,
1933, J S R, nymphs; February 19, 1934, 2. L. Fierce, nymphs; February
15, 1937, F K. Young, nymphs; April 3, 1937, L. B, nymphs; April 28,
1937, L. F, nymphs and. adults; May 10, 1937, L. B, nymphs; September
25, 1937, L. B., nymphs; October 30, 1937, L. B, nymphs; July 17, 1938,
L* B., adults; April 30, 1940, L. B, nymphs and adults); near Worthington
Springs (February 5, 1939, A. C.
Chable and Beck, nymphs); 3 miles north


372
routes: southwards from the mountains of North Georgia and eastwards into
the Suwannee drainage* and perhaps by way of the Mobile river drainage sys
tem. It seems likely that no one drainage system accounts for the present
distribution* but rather that all of those mentioned were involved.
LOCALITY RECORDS: Alachua Co. Hatchet creek (May 11, 1937, L. B., nymphs}
February 8, 1938, L. B., nymphe; February 26, 1938, L. B*, nymphs} March
23, 1938, L. B., adults} April 2, 1938, L. B., adultsj April 18, 1938, L. B.,
adults; May 6, 1933, L. B*, adults} July 9, 1938, L. B., adults; March
22, 1939, L. B., adults; April 1, 1939, L. B., adults; May 6, 1939, L* B.,
adults; June 24, 1939, L B., adults; October 11, 1939, L. B., adults;
August 10, 1940, L. B., adults; March 2, 1941, L* B,, adults)* 2 l/2 miles
vrest of Gainesville (April 4, 1937, L. B, nymphs; October 25, 1937, L. B.,
nymphs; November 8, 1937, L* B., nymphs; Maroh 5, 1938, L. B., nymphs;
August 9, 1938, L. 3., adults; Maroh 10, 1939, L. B, adults; April 21,
1939, L. B., adults); 3 miles north of Paradise (February 12, 1938, G. Van
Hyning, nymphs); 1 mile west of Lake Newnan (May 11, 1937, L. B,, nymphs;
October 4, 1937, L. B., nymphs; January 8, 1938, L* B., nymphs; January
25, 1938, L. B., adults; August 13, 1938, L. B,, adults); Eogtown oreek
(Maroh 14, 1933, J. 8. R., nymphs; May 10, 1937, L. B., nymphs; May 30,
1937, L. B., nymphs; September 25, 1937, L* B., nymphs; October 30, 1937,
L. B,, nymphs; July 27, 1938, L* B, adults; August 24, 1938, L. B., adults);
Campus, University of Florida (July 30, 1938, L. B*, nymphs and adults;
February 7, 1939, L. B0, adults; Maroh 10, 1939, L. B., adults; April 12,
1939, L# B., adults; April 20, 1939, L. B., nymphs and adults; November
11, 1939, L. B., adults; November 22, 1940, L. B., nymphs and adults);
Santa Fe river at Poe Springe (May 21, 1934, J. S. R., nymphs; March, 1935,


07
41 (40) remora of middle and hind legs with a ruddy dash anteriorly on
lower edge and g distinct ruddy spot near the apex and well beyond
the middle of the segment. Distal forceps segment much thinner
than third.
Pssudcclccon parvulum
41* Ruddy markings absent from legs. Distal forceps segment as
wide as third (see fig. 30).
Pseudocloeon alaohua
42 (40 ) A mid-ventral rox? of minute dots on posterior margins of sternites.
Sc reddish markings or. tergites 2-6.
Pseudocloeon punctiventris
42* fanal 1,paired,red spots on abdominal tergites 2-6.
t
\ i
Fsendocloeon bimaeulatus
i IYKIS
1
1*
Mandibles with no tusk visible from above (see fig. 1). Gills
present on abdominal segments 1-6 only, elytroid and fused on
segment 2. Hind wing pads present. Anterolateral angles of
prothorax produced forward.
("eoephemorinae) "Oreianthus sp. To. 1 Traver
Mandibles with or without mandibular tusk visible from above
(see figs. 1 and 2).
(2)
2 (1)
Mandibles with external tusks projecting forward and visible


and (barely seen) being seized by a male, after which the two seemed to
drift from the swam and settle to the ground where I lost sight of them*
The female could easily be distinguished by the brillinat orange eggs
which showed clearly through the translucent abdomen* I swept my net
through the swam once and captured seven males and two females. The
latter were probably in copulation with two of the males when they were
"so rudely interrupted," for as I lifted the females from the net, there
remained behind two clumps of orange colored eggs dropped by them as they
came in contact with the cloth* This dropping of eggs is very likely
correlated with mating because females taken by net that have not mated
will retain the ova, yet if copulation is in progress or has been com
pleted the eggs are released on oontaot. All during the flight, there
was a strong breeze blowing but this did not seem to disturb the flight
of the im&gos.
"The height of the flight of the swam was between six and eight feet
above the stream* The rise and fall of the males was between five and six
foot* The females seldom rose to this height*"
The most pronounced difference in the flight of proximum and smithae
is in the great rise and fall of the males of the fomer species# The
flight of other speoies of the interpunctatum group has not been described}
however, Smith (1935) has described the method of oviposition of one of the
species, and sinoe this has not been observed in proximum, I repeat his
observations* "This individual, when I first saw her, was flying straight
upstream, about five feet above the water, and was barely making headway
against the evening breeze* On the underside of the abdomen she was carry
ing a fairly large mass of eggs, ^ust as Ephemera11a does* The eggs were


S/r
176
although erven here they are not particularly numerous* I have collected
for several hours from the roots mentioned above but the catch "was small,
approximately twenty nymphs in all.
Tine nymphs are rathor tolerant insects if T raver s and my own ob
servations may be relied upon* T raver had one nymph (_0* purpure us) which
survived an automobile trip of three days, during which time the water
was ohanged only seldom each day. Several nymphs of "Orelanthus sp* No* 1",
confined in a half-pint jar in which the water was not changed, were brought
to Gainesville from Sweetwater creek, a distance of about 250 miles* They
were removed overnight to an open pan, but the following day were replaoed
in the jar for the remainder of the trip* In gainesville they were kept
in a pan of shallow water where they lived for a time, but, for some
undetermined reason, none lived longer than twenty days in captivity*
Two nymphs reached the emergenoe point, but died before transformation was
accomplished.
The most frequently encountered associates of Qreianthus nymphs are
Isonychia pictipes and I. perdido. Also very common in the root associa
tion are the inmaturas of Gaenis hilaris, Tricorythodes albilineatus,
Baetis spinosus, B* australis, B* spiethi, Pseudooloeon punctiventris,
Paraleptophlebia volitans, Hg.brophlebiodes brunneipennls, and occasion
ally Blasturus intermedius. Heacagenia wsewa and Baetlsoa rogorsi are
likewise found in the streams which Qreianthus inhabits*
SEASONS* "Qreianthus sp* No* 1" is strictly seasonal. Emergence takes
place during the spring in late March and April, and, to some extent, in
May* This is stated so positively because nymphs were taken from Sweet
water creek in November of 1938, yet in June, in the identical situation,


376
the remaining Florida species by the coloration of abdcsninal segments two
through six. The genitalia of australis are quite similar to those of
frorudalis and somewhat approach those of spinosus* The metathcracic wings
of these three species are all very similar in that they are long and nar
row, the 1 ngitudinal reins are reduced to two (the third being variable),
and the costal process is much reduced*
I have seen no females which could be assigned to australis, although
there are doubtlessly some included among the specimens which have been
identified as spinosus* The differences are probably so slight that the
females of these two species are indistinguishable. The nymphs are likewise
very difficult to separate, and I have found no characters which are easily
used* However, if a fairly large series is examined, it can be seen that the
lateral caudal filaments of spinosus are shorter than those of australis,
and, in the case of last instar male nymphs, the abdomen of the latter species
is unicolorous viiile that of the former is more variegate* Gills and mouth-
parts are very similar*
DISTRIBUTION: Present knowledge of the distribution seems to indicate that
B* australis is a Coastal Plain species* Traver described the insect from
specimens taker at Goshen Swamp, at Burnooat Swamp, and in Lenoir county,
North Carolina. Later, she recorded B* australis from Fort Valley, Georgia,
which is in the more hilly section of the Coastal Plain. I have found the
species ranging from Alachua comity in Florida all the way to the western
limits of southern Alabama* Probably its range extends as far south as Hills
borough county, Florida* but I have no adults and the nymphs from this area
seem to show only spinosus characters* Baetis frondalis McD*, to which
australis seems to be most closely related, is known from Ontario and Quebec;


389
"The older or moro primitive species of groups are northern in distri
bution or, if not northern, are active in the cooler seasons of the year
or cooler parts of the day." (ide, 1935). Further evidence in support
of this generalization has been added by Ide in his study on the effect
of temperature on mayflies. This oonoept is in conformity with morphological
evidence that spiethi is more advance than its closest relative, the more
northern pygmaeus, which is known from no farther south than the mountains
of Maryland and ¡Alest Virginia*
DISTRIBUTION* 3* spiethi is known to occur from Hillsborough county in
west-central Florida northward to the Georgia line and westward to Mobile
county, Alabama. Its distribution in Georgia is unknown, and there are
but few Alabama records* It seems, however, that in the eastern part of the
latter state the species does not extend far north, for no specimens were
taken north of Coneouh county* B* spiethi is probably as widespread in
Florida as spinosus, in spite of the fact that it has not been collected
from the northeastern part of the state*
Baetis spiethi is almost certainly confined to the Coastal Plain,
and very likely to its southern portion, although it may range northward
into the Carolinas. Ahil Traver's work in North Carolina did not bring
to light any of the pygmaeus group of species, it is probably that either
pygmaeus or spiethi or both ocour in this
ECOLOGY This inseot has been found to be most common in the smaller, more
slowly flowing creeks* Yiithin a particular stream, they are very similar
in habitat prexerence to B* spinosus* In general, the nymphs seem to re
main in quieter and shallower water than do those of spinosus, but almost
always the two live side by side* They are most frequently found in sand-


147
Indiana, concluded, also on the basis of measurements, that both speoieB
take only one year for development* however, he subsequently revised his
opinion, and now (verbal communication) believes a two year period more
likely This author (1938a : 32) sees "no reason why a species in the
northern part of its range might not take two years to mature, while in
the southern part of its range one year would be sufficient.
Since temperatures in the lakes of Florida seldom, or never, became
lew enough to stop growth completely, it would not be surprising to find
that H. limnophila completes its development within one year* Collections
made in early spring include rather small, half-grown, and almost mature
nymphs as well as intermediates. Since growth rate is a function of tempera
ture arid in the light of Spieths work (1938a) at Lake Wawasee in which
he showed that some nymphs of H* occulta grew as much as 16 mm. in eighty-
eight days during the summer and early fall, it would certainly be reason
able to expeot that all of these nymphs, in the warm Florida waters, would
have emerged sometime during the same year. When nymphs are taken in
autumn, the collection includes very young, half-grown, and individuals
which are perhaps two-thirds grown, but, of course, no mature speoimens.
The larger individuals of autumn would probably have emerged in spring or
early summer of the following year, the half-grown specimens would appear
in summer, and the very young nymphs would have emerged in late summer
or early autumn of the next year.
There is a definite brooding of h. limnophila. During the summer,
the broods may sometimes be separated by not more than a week or ten days;
at other times, the intervening period may be much longer. In the spring
and early summer the emerging broods are smaller, on an average, than


Ill
"There is very little or no current beneath the recks, and the oxygen con
tent here has been found to be about the same in the lakes as in the
streams* A species living under these mild current conditions would be
expected to have conservative current resisting adaptations." The flatten
ing of the body, the femora, and the spreading of the legs all are adjust
ed in such a way aB to reduce resistance to a minimum in this rheocolous
mayfly, otenonema. S smithae is no more, nor any less, flattened than
other species of Stenonema and could probably withstand just as strong
current as the strongest in whioh its kindred species dwell.
LIFE HISTORY- I have attempted several times to rear this species freon the
egg, but, in every case, after a few days all nymphs died. To get the
eggs to hatch was simple, to go much beyond this stage is another matter.
The crux of the situation is probably in the food supply* Introduction
of food invariably introduces other organisms, and once these are present,
they seem to multiply at such a rapid rate that the competition offered
by them is much too much for the delicate mayfly nymphs.
Nymphal development in the genus St e no nema has been studied intensively
for only two species, JS. interpunctatum and S canadense. The former
species was examined from the first through the eleventh instars and the
changes noted; however, no data were presented on the actual number of
instars nor wus there an estimate of the length of life of the nymph.
Ide (1935b), studying S, canadense, described the first through the sixth,
the eighth, tenth, eleventh, twelfth, fourteenth, and fifteenth instars,
and estimated the total number of molts to be between forty and forty-five,
but he, too, failed to give the actual length of life of the species. Skipping
the intermediate instars, he then described the ootult, septult, qulntulfc.


254
data, but is is evident that emergence must take place during the spring*
of vibrans in Quebec, McBunnough says that adults are very common in
late June5 my Georgia specimens were taken in late April.
HABITSt There is nothing known concerning the habits of the North
American nymphs, but I would assume that they are much the same as those
of Habrophlebtodes brumelpermis* The only reference to habits of adults
is one concerning their mating flight written by Dr. Needham* "Some
of tiie lesser, rivulet-inhabiting species, such as Habrophlebia vibrans
swarm in compact little companies in forest openings by the brookside,
the individuals dancing up and down so close together that a single stroke
of a large net may capture scores of them and may largely depopulate the
swarm*B (from "The Biology of Mayflies", page 102)*
LIFE HISTORY* Nothing is known of the life history but as a mere con
jecture, I would say that to pass from egg to adult requires eight to
ton months, perhaps a year*
DJRf/ATIuN OF THE SPECIES: II* vibrans does not appear to be southern
in origin, at least not in the lowlands of the Coastal Plain* The head
waters of the Chattahoochee river drain the foothills of the Appalachians,
the river then proceeding southwards to join the Flint at the Florida
state line* It is quite likely that this was the highway of ingression
for vibrans.
LOCALITY RECORDS: Jackson Co. 3*5 miles north of Altha (December 10,
1937, L. B*, nymph)* Okaloosa Co. 2.3 miles east of Niceville,(April 3,
1933, H* II* H and L* J* M, nymph)*


3<51
quilleri type. McDunnough, even in his caustic review of Baetis, follows
Traver's divisions, but he states that several of her species placements
are erroneous. The Florida species of Baetis fall into the true moffati,
the spinosus, and the irrberoalaris types*
The species of Baetis are rather generally distributed throughout the
world, occurring in the llolarctic. Neotropical, and Indo-Australian faunal
regions* In the Neurotic and Neotropical regions, the genus is widely dis
persed from southern South America to the Arctic region in North America,
its only limitation apparently being the presence of permanently moving
water*
Because of the overlapping of many generio oharaoters, Spieth considers
it likely that the "classification [of the Baetinae] may be and probably is
an artificial one, and thaii iu can not be said with certainty that it re
presents a picture of the phylogenetic history of the group*" He considers
Ac entre 11a and lleterooloeon as merely subdivision of Baetis and also sug
gests that Pseudooloeon, even though it completely lacks hind wings, should
also be included as one of the groups under Baetis I cannot agree with
this latter conclusion, for, even though the female of Baetis spiethl
possesses hind wings of microscopic proportions, I believe that the complete
absence of wings should be sufficient to segregrate these groups into higher
categories than subgenera. Baetis is probably derived from some stook whioh
was basically similar to dallibaetis* The author quoted above distinguishes
three distinct lines of evolution in the Baetinaet (l) Callibaetis (2)
Baetis and Pseudooloeon (3) Centroptilum and Cloeon*
Within the genus Baetis (s* s*), there are at least three lines of
development when the hind wings are considered enlarged wings with three


324
the genus Brachycerous to include those species which had previously been
placed in Euryoaenis. It is obvious from a study of adults that the
species of Caenis and those of Brachyceroua form a closely knit phylo*
genetic unit; this is seen both in wing characters and in genitalia*
Travel' (19351 630) has included the genus Tricorythodes in the same
subfamily with the other genera mentioned above as did Ulmer (1933 206)?
however, Spieth (1933: 355) disagreed with this arrangement stating that
the resemblances are merely superficial.
Brachycerous nymphs are rather unusual in appearance, belonging to
that large assemblage of mayflies which have operoulate gill covers to
act as protectors of the more delicate, highly tracheate posterior gills.
These nymphs are easily separated from those of Caenis by the presence
of tubercles on the hoad and by the depressed body form; from those of
Tricorythodes by the tubercles on the head,by the shape of the body, and
by the faot that the latter nymphs have triangular operoulate gill covers?
from, those of Oreianthua by the presenoe of the head tubercles and by
the presence of hind wing pads in the Oreianthus nymphs? and finally
from those of Ephemeralla by the faot that the operoulate gill oovers
of Brachycerous are on the second abdominal segment while in Ephemerella
they are on either the third or fourth segment*
The following key, adapted from Traver (1935: 639), will separate
the North American species of Brachycerous.
1* Small species (wings 3.0 mm* in length).
(2)
1' Larger species (wings 3.8-5.0 mm* in length).
(3)
2 (l) Meso- and metanota straw to canary yellow? fore femur light


420
in these mayfly groups may have arisen by direct and independent mutation
from a form such as B* parvus* It is not necessary that there has been
a gradual decrease in the size of the hind wings* The Pseudocloeon species
may be more closely related to a species of Baetis than are two species
which are now unquestionably regarded as members of that genus.
Although Spieths reasoning seems fairly sound, and Pseudocloeon may
represent only an artificial grouping of species, I feel that because of
the convenience of arrangement, the genus should be retained. Further evi
dence to substantiate Spieths argument is shown by the gradual diminution
in size of the hind wings of females of certain species of Baetis* Speci
fically, the metathoracic wing of Baetis splethl females is so minute
that in some specimens it is almost invisible and can be detected only by
closest scrutiny of the lateral surface of the metathorax. Again, a series
of Baetis nymphs of various species can be arranged to show all gradations
in size of the median caudal filament*
In Florida, the nymphs of Pseudocloeon are confined to running water
although in the northern United States and Canada some species have been
reported inhabiting lake margins*
Pseudocloeon alaohua Berner
TAXONOMY Pseudocloeon alaohua was described from Florida in 1940* Al
though similar to P* parvulum, it differs in having long thin foroeps, no
intercalary veinlets in the first interspace of the fore wing, and abdominal
segments two through six are hyaline whitish but marked with brownish-red
patches* The nymphs are muoh like those of F* parvulum, but are easily
separated from them by their weakly banded oaudal filaments and the absence


194
main by swimming rather than orawling, the ohief mode of locomotion of the
majority of other,, but weaker, stream inhabiting species*
The rate of regeneration of caudal filaments is rather rapid# A
nymph brought into the laboratory at Gainesville was somewhat damaged
in that it laoked half of its right tail and two-thirds of its middle.
This condition was noted on March 12 and the nymph was in its penultimate
instar# After the molt to the last instar on Maroh 18, the complete tails
were again present and were of normal length#
That the subimagos are rather sensitive to moisture conditions v/as
discovered when attempts were made to secure imagos by keeping the sub
adults in a paper sack. Out of several subimagos collected, not a single
specimen molted completely, and most of them died before even beginning the
imaginal molt* After emergence the adults remain directly over the strean.
All specimens were collected either at light at the shore of creeks or
from trees or bridges over them. The subimagos and imagos are distinctly
phototropic, although the latter are less so. At the lighted sheet, the
subimagos tend to alight in a poorly illuminated area near the ground.
Those specimens which were attracted did not all come at once, but inter
mittently over a period of approximately two hours.
LIFE HISTORY: From the arrival of the subimagos at the lighting sheet
over a two hour period, it would seem that emergence probably occurs at
this time. The light was kept burning from seven to nine in the evening,
beginning just as darkness fell and continued until no more ephemerids wore
attracted. The subijnaginal period of those specimens which did partially
molt lasted twenty to twenty-two hours. Surprising, this period does not
differ muoh from that of Isonychia albomanioata and I# aurea in North


61
(1) Sink-hole ponds; These ponds are formed by the dissolution of under
lying limestone. Rainwater, percolating downward to the water table, dis
solves vertical chimneys in the limerock into which the surface cover may
l\
collapse gradually or suddenly, producing a steep-walled, open sink. Where
the oover is thicker or less oompact a saucer-shaped or funnel-shaped depres
sion may result. There are many of these ponds of sink-hole origin in
Florida, and in particular around the Gainesville area. Some of them are
dry but the great majority have standing water, which maintains a fairly
constant level because the water table is high enough to supply the ponds
continually. The sides of the ponds both above and below the water level
are steep and the zone of rooted aquatic vegetation is very limited. The
sides of the sink-holes above the water are usually covered with vegetation
which extends from the edge of the water up to the rim of the depression*
In many of the sink holes a narrow sand beaoh may be fomed where the slope
of the sides levels off, but the shore zone exfcendint into the water from
this beaoh is very narrow, and the drop to deep water rapid. There are
two ohief types of sink-hole ponds*
(a) Ponds with the surface free of vegetation* This is one of the
common types of sink-hole ponds encountered in peninsular Florida.
The margin of the pond has a fairly rioh growth of both submergent and
emergent vegetation, which extends outward to the region where the drop
off occurs. This is oomposed principally of Saocrolepis striata, Per-
Be paria, Mayaoa fluvitalis, Juneus, and some Typha as well as numerous
species of algae. This sudden drop to deeper water begins at a depth
of about four and extends to a depth of about ten feetj thence the drop
continues more gradually to about twenty feet. In many of the ponds


lie
swarm, the female flying off to oviposit. Cooke (1940) made an interest
ing observation on the copul at cry approach of the sexes of S. vicariun
during flights "Females showed very lit"le tendency to take part in the
flights. The captures of two complete companies of imagoes and of tho
greater portion of a third yielded only one female, which ivas taken with
the second group. It is probable that this female had just entered the
swam from beneath, booau.se when a single female was seen passing below
a company of males it was seldom disturbed; on the other hand, when it
passed a few feet above or directly through the swarm, it was instantly
attacked by them* The large eyes of the males are situated on the dorso
lateral regions of the head, a location which perhaps enables this sex to
see females above them better than below. All attempts to mate were made
by the male flying up beneath the female placing his forelegs over her
prothorax and head. With upeurved abdomen he grasped the body of the fe
male with his forceps near her seventh abdominal segment and mating thus
be come s e ffective."
Observations on the evipositon of the females demonstrated an in
teresting behavior. The insect flies low over the water, about six to
twelve inches above the surface. At intervals, the abdomen is touched
to the surfs, e where the current is rather noticeable, the action resembling
that cf a dragonfly or damsel fly. The ovipositing flight, for the most
part up and down but occasionally cross stream, is not composed of pro
nounced risings and fallings such as take place during the mating flights,
but is more directive. The eggs are released, a few at a time, until the
female is spent, when she flies to some low hanging bush. The horizontal
flight may cover a distance varying between twenty and fifty feet, oviposi-


219
emptying into the Apalachicola* In these larger, but still shallow,
streams the nymphs can be commonly found near the banks among the roots
of terrestrial plants, -which project into the water*
The sand-bottom streams from which nymphs have been taken are, for
the most part, circua-neutral or acid, and usually drain flatwoods. The
vmter is usually tinted, the tint ranging anywhere from almost colorless
to the color of strong tea.
Subimagos are confined to moist, heavily shaded areas along the
creek banks or to any other shaded area above the stream where the humidity
is very h igh* The subimago molts only with great diffioulty in the lab
oratory j in fact, it is rare for a male under such conditions to complete
its final ecdysis successfully. Even specimens placed under bell-jars failed
to shed. Attempts made in a dry atmosphere failed even more miserably.
Dr. B. D, Burks, Illinois Natural History Survey,states in a recent
letter concerning the Illinois species, "Usually I have not had any diffi
culties with the sbimagos once I get them out of the water, as I have
found that they need to lose moisture, and so I keep them in fairly dry
jars in a cool, dark place." I tried this method, but on the morning
following emergence, as usual, the insects lay dead and withered on the
bottom of the container. Of all species of mayflies with which I heve
dealt, volitans has the most difficulty in completing the last molt*
SEASONSi Available records for Florida adults indicate that in this region
the species emerges the year youndj however, in Canada (Algonquin Park,
Ontario), Ide (1940) reported that emergence takes place in the later half
of duly and in August. Truver, in recording the species frem the south.
did not givw the date of collection. Among the Florida specimens, there




64
banks or at curves* debris accumulates to a rather marked degree in some
of the streams, almost any obstacle forming a nucleus for tne accumulation
of much leaf drift, sticks, etc* Tree brunks frequently form dams and give
rise to riffles, while the tangle of branches and twigs provides a network
in which, much detritus becomes entangled tilt accumulates near the shore
and in places may produce rather thick deposits, in some streams even forming
a layer more than two feet in thickness; however, for the most part, the
silt deposits in the sand-bottom streams are sparse and of little consequence*
Near shore, leaf drift becomes a fairly important habitat, for many insects
are harbored in this material, and in the almost stagnant shore pools the
leaf debris may be several layers thick, interspersed with silt* The flow
of water in the sand-bottom streams is never rapid in the sense in which
a nortliern stream is said to be rapid; rather, the flow is gentle with the
surface seldom breaking* Most of these streams are oiroum-neutral to slight
ly acid, butt some may be pronouncedly acidic* Nearly all of them have
tinted waters which vary in shades from almost colorless to a strong tea
color according to the area drained and to the amount of rainfall* Most
of the streams drain flatwoods, hammock lands, or swampy areas, and are
fed by springs or diffuse seepage areas. Vegetation is almost completely
absent from the streams except for a few scattered Orontium plants and an
occasional dump of her si caria near the quiet shore zone; however, these
plants are not particularly important from the standpoint of furnishing
habitats for mayflies*
(2) band-bottom creeks choked with vegetation: This sort of stream occurs
mostly in the northwestern part of Florida beyond the Apalachicola river.
The beds of the creeks are composed of fairly loose sarad, but instead of


279
loosa county streams were both present* Hare, the nymphs wBre found to be
a more conspicuous element of the ephemerid fauna than in any other Florida
stream whioh I have examined. The nymphs were commonest in the dense mats
of Potomogeton in the more gently flowing water, but were also present on
the roots projecting from the undercut banks. The species was also found
along the undercut banks of a small,moderately swift-flowing stream.
The streams,in which this species of Ephemeralla lives,vary from
strongly to moderately acid, and drain the red-clay hills of the Citronelle
formation or the flatwoods and swamps of the lowlands* All of the streams
are permanent and have a moderate to rather swift flow; none is more than
three feet nor less than six inches in depth.
In the root masses of Sweetwater creek, the mayfly assooiates are
Isonyohia pietipes,nOreianthus sp Ho. 1", Caenis hilaris, Baetis spiethi,
B* intercalaris, B. australis, 3 spinosus, Paraleptophlebia volitans,
Habrophlebiodes brunneipennis, Ephemerelia trilineata, Stenonema smithae,
Trloorythodes albllineatus, and occasionally a nymph of the burrower Hex-
agenla woewa. In other streams, ephemerid relatives of E. apalaohioola
are not so varied, and in addition may inolude Choroterpes hubbelli, Pseudo-
oloeon bimaoulatus, and Acentrelia ephippiatus.
SEASONSi My only reoords of E. apalaohioola are for the months of April,
May, June, and July* The April and May nymphs are all in their last instar;
the June records inolude nymphs of all ages ranging from those less than
one-third the length of mature individuals (in volume perhaps one tenth as
large) to last instars. This would seem to indicate a year round emergence,
but I do not believe that this aotually occurs; rather, the data point
to an emergence beginning in spring and extending through early fall, with


tion of the habite of B. thompsonae (1337) indicates that the immatures
of the two species occupy similar habitats The greater development of the
lateral spines in the nymphs of these two species is probably correlated
with the ability to maintain themselves in moderately to swiftly flowing
water* The Baetisca nymphs, with their short, rotund bodies, would cer
tainly find it rather difficult to retain their position in the gravel,
even though using their claws for clinging to the substratum, without these
long projections to act as balancers." (Berner, 1540b : 153). Nearly
fifty nymphs were collected from two small riffles in a sand-bottom creek
in ladsden countyj these nymphs lay between the small pebbles, partially
covered by sand, with their heads upstream. There was little movement,
and this was seldom by swimming.
A few nymphs have been taken from streams emptying into the Choctaw-
hat che e Bay. (Jne specimen was collected by sweeping a dip net through
the dense mass of Vallisnerla, Potomogetcn, Sagittaria, etc. which choked
the stream; in the same stream, another nymph was seen clinging to the
underside of a submerged log which did not rest on the bottom. A second
creek near Niceville yielded three nymphs from the undersides of boards
which were partially imbedded in the bottom of the stream. The boards
were to some extent covered with sand, and many sand particles adhered to
the undersurfaces making it quite difficult to discern the nymphs. One
of the unusual aspects of these situations was their proximity to salt water.
The former stream is completely fresh beyond t. e margin of the bay even
though the flow is not extraordinarily rapid. Baetisca was taken not more
than one hundred yards from this salt water; however, there is no doubt
but that the nymphs could have lived much closer for nymphs of Chorfeterpes


21
turbinate eyes are brightly colored in shades varying from yellow to
orange to brown. It is thought that this exceptional growth of the eyee
of the males is correlated with the habit of aerial mating, for in this
flight the male approaclies the female from below* It has been pointed out
by Cooke (1340) that the specializations have reached such a state of devel
opment that if a male (of btenoneua vioarium) be approached by a female
from below, she will be completely ignored, probably because she is in
visible to the male; however# if the female is above the male, she is
ira -: diately seized and copulation ensues*
The legs of mayflies, although primitive in some respeots, are really
highly modified organs* Adult mayflies do very little walking and no
running whatsoever* In certain groups, i. e* Campsurus, the legs (except
the fore lags of the male) have became vestigial, and the adult can no
longer alight but xaust remain on the wing during its entire ia&ginal life*
horgan (1923: 63), in her description of the mating flight of C segnis,
states that "in the extreme specialization which Campsurus segnis has at
tained the brevity of its aerial life has been a necessary parallel to the
abbreviation of its legs. The adults are entirely dependent upon their
wings for existence* Since they have no legs to rest upon neither males
nor females can alight upon anything and if they are forced down there is
little chance that they can ever fly again*" The forelegs of male mayflies
are elongated and have been provided with a reversible joint at the base
of the tarsus as specializations for seizing the female during the mating
flight. The mere specialized mayflies show a tendency toward a reduction
in number of tarsal sequents in the two posterior pairs of legs by fusion
of the basal segments with the tibia.


259
hubbelll and Ephemeralla trilineata were taken within twenty-five feet
of the Bay# At the Niceville stream, nymphs were collected from within
five feet of the salt water, where the oreek became very shallow and wide
but still had a moderately swift flow.
All streams in which I have found Baetisca nymphs are sand bottom,
slightly aoid or oiroum-neutral, and have rather clear water. These streams
drain upland regions where there is relatively little swamp land and con
sequently the water picks up only a small amount of humio aoid. During the
winter, temperature readings were not taken in these oreeks, but there are
usually heavy frosts in the western part of the state; in some of the
more slowly flowing streams west of the Apalachicola river, I have seen
ice near the banks in December. Growth of nymphs is slowed considerably
by the oold, but as soon as warm weather returns, more rapid growth is
resumed. Ide has shown that emergence is linked with temperature, and ,
even though many Florida species are not affected, several of those in
the northwestern part of the state most certainly are.
The mayfly nymphs associated with Baetisca rogersl nymphs in the riffles
are Stenonema smithae (younger forms predominate), Baetis spinosus, B. aus
tralis, and Pseudooloeon dubium. Now and then, a specimen of S. exlguum,
one of the Isonyohlas, or a young Leptophlebine may be taken from the riffles.
On the underside of the boards on which Baetisca nymphs were found are
also S. smithae and S. exlguum. The eel-grass association is the same as
that of Pseudooloeon bimaoulatus.
The adults, not differing from other mayflies, are normall oonfined
to the mesophytic hammocks lining the stream margins. Here the humidity
is fairly high and the adults experience little difficulty in undergoing


77
Hexagenia (5)
5 (4) Penes slender, somewhat beak-shaped (see fig* 6); abdomen banded
longitudinally with, dark and light areas*
Hexagenia bilineata
5' Penes more or less hook-like (see fig* 7); abdominal markings
not as above.
(6)
6 (5) Body of female canary yellow; dark abdominal markings limited;
fore wing 24-28 mm* Male prominently marked; hind wing with wide
purplish-brown border, large dark spots near middle; many cross
veins of fore wings widely margined with purplish-brown* Distal
segment of middle and hind legs dark on under side* (see fig* 7).
Hexagenia weowa
6 Body of female and male heavily marked with purplish brown. Hind
wing with or without wide purplish-brown border and brownish spots
in middle; if brown border and blackish spots present, outer seg
ment only of middle and hind legs dark on underside.
(7)
ft
7 (6*) Hind wing without prominent purpliBh-brown border and no large
blackish spots (see fig. 4). Ouber segment of middle and hind legs
with dark markings on underside* Female yellowish with a tinge of
brown. Inhabits lakes.
Hexagenia limnophila
7' Hind wing of male with prominent purplish-brown border and large
blackish spots* many cross veins of fore wings widely margined
with purplish brown* Ouber segment only of middle and hind legs


325
purplish brown; abdominal tergites creamy white, 8-10 with
a purplish black mid-dorsal streak
flavus
2 Meso- and metanota light brown} fore femora pale smoky; ab
dominal tergites yellowish white, immaculate*
prudens
3 (1') Mesonotum dark red-brown, metanotum purplish; tergites 1-6
purplish gray, margins lavender; posterior margins of stemites
purplish.
nit id us
3* Mesonotum paler brown; metanotum similar*
(4)
4 (3') Tergites 1-6 pale, posterior margins blaokish; dark lateral
spots on some of the sternites*
idei
4 Tergites 1-6 prominently mottled; mid-dorsal line evident
on tergites 6-9j sternites without spots; anterior margins
of sternites 1-9 blaokish.
maoulatum
The species of Braohyoerous aire known from widely scattered loca
lities. B. flavus was described from Louisanna at the Texas state line;
idei is known from Ontario; nit idus occurs in the Appalachian region of
North Carolina; prudens has been recorded from Saskatchewan and Kansas;
and lacustris from Miohigan and New York. The new species maoulatum
is known to occur only in Florida*
It would seem that the genus, which is Holarotio and African, is


106
although predators are rather numerous, the nymphs are still well pro
tected Young nymphs seem to predominate in the riffles but this is not
always the ease and frequently older specimens will be the only ones taken*
At one time or another almost every Florida species cf mayfly has
been collected along with S* smithae except Hexagenia limnophila arid Calli-
baetis floridanus floridanus In its favored haunt, the submerged logs
and boards, only' few species ere associated with S* smithae. Those include
S* proximum, S exiguuE, I)aetis spinosna, B, spletM, ^oerdo vlcoc.n alach.ua,
and Triccrythedes albilineatus* The ftencuerna species are the only ones
which occupy the undersurfaces of the supports to any extent, the others
tending to remain on the sides or on the upper surface In leaf drift,
the Leptophlebine mayflies are found in addition to Tact is species*
bEASO'TSj September is the only month of the year for which I do not have
adult sx-ec' mens and this is easily explained by lack of collecting during
this ta. S. smit ae follow's the Ba.etid.ae in its year round emergence
and there seems to be no definite period of maximum transformation* There
is a slight indication that there may be a greater preponderance of adults
during the summer months, but this is due only to the slowin of emergence
during cold snapsj however, as scon as warm weather returns, the adults
begin coming out once more* lymphs of all ages can bo collected from any
one stream at any time of the year, and there is no tendency toward brood
ing* Of course, since temperatures are slightly more uniform and higher
in north-central than in northwest Florida, there is a greater amount of
emergence during the winter months because of the longer warm spells. The
specimens collected in Alabama by Traver were taken during July and offer
no indication of seasonal range in the more northerly limits of the geo-




so
much deeper beyond this region; in the deeper parts other vegetation
which can stand greater degrees of submergence is present* The bottom
of the ditches is usually covered with grasses and may have heavy growths
of Globifera umbrosa, Isnardia, and Persicaria* Algae form dense mats
in some of the ditches along with Ubrioularla, Geratophyllum, Potamogetn,
and Myriophyllum. At times the water may become very warm, in fact hot,
during the summer; in winter it is often quite oold, with ice sometimes
forming over the surface* The water in these ditches is usually acid but
may be basic; the lowest pH recorded was slightly above 4*0. The depth
of the water varies from a few inches to as much as four or five feet, and
the width of the ditch (that part containing the water) may be from one
to fifteen or more feet*
(2) Puddles In this category are placed those small and transitory bodies
of water left by the retreat of a stream or formed by heavy rains* There
is no, or very little, aquatic vegetation in such puddles, and it is
only by remote chance that organisms are found in them* Such animals are
stream relicts which soon perish, for the puddles dry up rapidly during
dry weather; however, I have found mayflies in such places and for that
reason I am including this situation* In some of the puddles there may be
several layers of leaf debris. Silt accunulates between the leaves and
algae begin to grow, continuing as long as the water remains*
Ponds
The ponds of Florida may be divided into several types, but nearly all
of them share one characteristic in common they seldom have streams
draining into or from them*


308
DATE KILLED
Got* 30
Nov* 6
Nov* 13
Nov* 22
Nov. 27
Dec* 4
Dec* 4
(1 speci
men)
BODY LENGTH
,42 mm*
*49 mm.
50 mm*
83 mm*
.93 mm*
1*16 mm.
55 mm*
ANTENNAL
LENGTH
,2 mm.
32 mm*
*38 mm*
*73 mm*
80 mm*
85 mm*
45 mm*
ANTENNAL
SEGMENTS
5
6 (?)
6-7
9-10
11-12
14-16
8 (?)
LENGTH OF
LATERAL C.ERCI
.36 mm*
*66 mm*
68 mm*
1*0 mm*
1*2 mm*
1.65 mm.
68 mm*
NO. SEGMENTS
IN LATERAL
CERCI
5
6 (?)
6-7
9-11
14-16
25 (?)
?
LENGTH OF
MEDIAN CAUDAL
FILAMENT
*36 mm*
67 mm*
68 mm*
1*1 mm*
1*2 mm*
1* 6 mm*
broken
NO. SEGMENTS
IN MEDIAN
FILAMENT
5
6 (?)
6-7
9-10
14-15
?
broken
LENGTH OF
FORE TIBIO-
TARSUS
1 mm*
11 mm*
11 mm*
17 mm.
*21 mm.
3 mm*
?
length OF
fore CLAW
045 mm*
056 mm*
*066 mm*
07 mnu
075 mm*
075 mm*
?
GILLS
PRESENT
No
No
No (in on6
case)
In some
Yes
Yes
No
Average measurements showing the rate of growth of Caenis diminuta nymphs
ver about one-fourth of their early life*


164
life history, and mating flight of Ft, bilineata.
DERIVATION OF THE SPECIESi The movement of the species into Florida
(for certainly the species does not appear to have originated in the
state) was discussed above under the topic of geographic distribution,
H* bilineata is one of the most distinctive of the species of Hexagenia
in North America, and probably represents a separate stock which subse
quently gave rise to several subspecies,
LOCALITY RECORDS Jackson Co, Blue Springs Creek near Marianna (June
5, 1940, H. H, H. and L, B., adults).


198
H BITS AED LIFE HISTORY: Habits and life history of the species are no
different from these of I. perdido.
DERIVATION OF THE SPECIES: The entrance of L, plotlpes into Florida is
easily followed by examination of its distribution in Georgia. The Aloova
river, the type locality, flows directly into the Flint river which in
turn is one of the principal branches of the Apalachicola; the Apalachee
flows into the Ogeechee and from this drainage the species oould easily^
enter that of the 3uwanr.ee* Thus the ingress of I* pictipes into this,
its southernmost range is seen to have followed the drainage of the
largest rivers leaving Georgia and passing through Florida*
LOCALITY RECORDS: Alachua Co. Santa Fe river at Poe Springs (March,
1935, J* S R., nymphs; tiarch 12, 1938, L* B., nymph). Gadsden Co*
4 l/2 miles south of River Junction (March 17, 1939, J. S. R* H* H* H*,
F* N* Y., L. B., nymphs; June 30, 1939, L. J. M. and L. E., adults;
June 6, 1940, H. H* H* and L. B., nymphs and adults). Gilchrist Co.
Suwannee river at Oldtovm (April, 1938, L. B*, nymphs). Liberty Co.
10 miles south of River Junction (March 17, 1939, J. S. R., H* H. H.,
F. N* Y, L. B., nymphs); Sweetwater creek (duly 1, 1939, L* J* M. and
L. B., nymphs; December 1, 1939, H. H* H. and L. B*, nymphs and adults).
Suwannee Co* Suwannee river at Branford (May 29, 1940, H* K* E* and
L. B., adult). Washington Co. Holmes creek (July 29, 1939, L. J* M.
and L. B, adults).
Isonychia sp* B
TAXONOMY: Determination of a species in this genus makes it almost impera
tive that males be at.hand. Sino6 I have been unable to secure this sex


11
ticulary efficient mechanism for obtaining oxygen* Even the feeding habits
have become modified to such an extent that these nymphs, much like earth
worms, oat the organio materials encountered in their burrowing; however,
they seem to feed somewhat selectively, since surprisingly little sand is
found in their digestive tracts*
Numerous other distinctive modifications of form and structure are
encountered among those nymphs whioh do not burrow, and they are directly
related to the habits end habitats in whioh the nymphs normally live*
Dodds and Hisaw (1924) have shown that nymphs whioh live on the undersides
of rooks in mid-stream, where there is almost no current, have flattened
bodies, while the bodies of those inhabiting the swiftest waters are tor
pedo shaped* Still others with rounded, streamlined bodies dwell in ponds,
but here it is the ability to swim and dart about rapidly that is correlat
ed with the streamlined form*
I have found that there is a definite correlation between claw size
and habitat* Those species which dwell in ponds and in very slowly flowing
water have thin, attenuated claws whioh lightly touch the object to which
the insect is clinging, but they do not form a strong damp* A nymph
with suoh long claws would probably have difficulty in maintaining itself
in a strong current, for the claws could soarcely have sufficient leverage
to support the insect in this situation* The mayflies living in swifter
currents have short, thick claws whioh clamp firmly into the object on
which the insect i6 living* The stronger the current, in general, the
shorter and thicker the claws* Mayflies from rapids have very short thick
claws, often with strong teeth on the underside, and in one species that
I have examined this pectination has gone so far that the entire tarsal


30
a definite color pattern overlying the white of segments 2-6, but this
is never conspicuous* In nearly all cases, this strongly localized
coloration is limited to specialized genera of mayflies which are less
than ten millimeters in length* It is probable that the glistening wings
and the hyaline sequents help to render the insects inconspicuous because
there is euoh a great reduction in the amount of dark color exposed to
the view of predators* The females of these species have uniformally
colored abdomens, but it has been suggested that if the entire exoskele
ton of these insects were transparent, the light colored musoles as well
as the egg masses would show through and the females would be easily seen*
Differences in maoulation are reliable, in general, for distinguish
ing species, biit the great degree of variability in some species causes
misgivings whenever color pattern, unless it is absolutely distinctive, is
used* The genus Stenonama is one of the chief groups in which color has
been used for the establishment of new species; however, it should be
employed with caution* In Florida,a species of Stenonema occurs which by
its color pattern might fit into any one of three species, S. proximum
(the name used for it in this paper), S* pallidum, or interpunctatum.
Probably (just as was found to be true of S* tripunotatum, described below)
S* proximum and pallidum will prove to be local variants or seasonal forms
of S* interpunotatum*
To distinguish between species, oolorationai differences have probably
been employed more than any other character or group of characters*
Spieth (1938) made a study of coloration and its relation to seasonal
emergence in the Ephemeroptera, and from his study it appears that some
of the species, which have been described solely on the basis of maoulation-


548
1940, nymphs); Santa Fe River (October 25, 1939, L B, adults); San
FelaSCO hammock (October 26, 1937, H X. Wallace, adults); 2 l/2 miles
northwest of Gainesville (November 6, 1937, J# S# R., J. M. Martin, L. TV,
nymphs and adults)* Bay Co# 28.3 miles north of Panama City (June 8,
1938, H. 11 H#, F. IT, Y., L. B., nymphs); 3 miles west of county line
(May 30, 1940, 11# II# H# and L. B#, nymphs)* Citrus Co# 1 l/2 miles south
of the Withlacoochee river (March 25, 1938, L. B, nymphs). Columbia Co#
2,7 miles north of Lake C5.ty (October 27, 1938, H# H. H* and F# N# Y., nymphs) j;
19.6 miles north of Lake City (Cotober 27, 1938, H. H. IT. and F, IT* Y*,
nymphs); 1 mile northwest of Ocean Pond (May 12, 1937, L* B,, nymphs).
Franklin Co# 4.5 miles west of Carabelle (June 6, 1938, II# H. H#, F. N# Y#,
L. B., nymphs). Hamilton Co# #6 miles : orth of Live Oak roat at U. S.
Hwy# # 41 (February 4, 1938, L. B., nymphs); 1 mile north of White Springs
(February 4, 1938, L. B., nymphs); 41 miles northwest of White Springs
(February 4, 1938, L. B., nymphs). Hillsborough Co# 2 miles east of
Tampa (Maroh 26, 1938, L. B., nymphs); Hillsborough river State Park
(August 16, 1938, T E. Eubbell and J. J Friauf, adults). Holmes Co#
1.2 miles west of county line (June 8, 1938, L. B., adult). Leon Co#
13.8 miles west of Ta'lahassee (June 5, 1938, L. B., nymphs); 20.3 miles
vest of Tallahassee (June 5, 1938, L. B#, nymphs). Madison Co# 5.9 miles
vest of Madison (February 5, 1953, K. H* H, and L B., nymphs). Marion
Co# Orange Springs (October 2, 1937, L# B#, nymphs); near Oklawaha river
(February 12, 1938, nymphs); Ocala national Forest (February 12, 1938, L. B.,
nymphs; adults); Ocala national Forest (March 19, 1938, S. Spur, nymphs);
Ocala National Forest (July 24, 1938, T. H. Hubbell and J. J. Friauf, adults)#
Pasco Co. 20 miles north of Tampa (March 25, 1938, L. B,f nymphs);


Hap* 20* Dist
Pseudoeloaon
P* puncrblventr
latuE.
ribution of
alachua* P. dubiiiri
is* and blraacu-
p
> alachua
P
ublaa
if J
punotiventris
vS
+ +
P
V
. 4-
X
!
i
o


272
epidermis of decaying vegetation, as well as that of living plants, for
the alimentary canal was packed with plant fibers and other cellulose
materials.
The bicolor group of the genus Ephemerella, in the nymphal stage, is
characterized by the absence of gills from segments two and three and by
the modification of the fourth gills into gill covers. When the nymphs res
pire, water is circulated about the gills by the lifting of the operculate
covers and the rapid vibration of the fifth, sixth, and seventh pairs of
gills, formally, both gill covers are raised at the same time, but I have
observed on numerous occasions that one gill cover may remain tightly closed
while the other is raised and the gills under it rapidly vibrated.
LIFE HISTOI: A study of the material in my collection indicates clearly
that the life history of trilineata occupies approximately one year.
Last instar nymphs have been taken from January through the middle and lat
ter part of June, but during July, August, September, and October there
are no records, although I have collected in streams from which nymphs were
taken during the remaining months of the year. In November, very young
nymphs were collected and it therefore seems reasonable to suppose that
during the middle summer and fall period, the eggs were developing,and
the young nymphs, too mall to be retained by my collecting apparatus, were
the only stages represented. Nymphs one-third to two-thirds grown were
found in December and some were even in the penultimate instar. In March,
rather immature specimens were taken in Hillsborough county these were
obviously the summer crop.
Transformation has not been observed in the field, but in the laboratory
the nymphs, just before emergence, swim vigorously about, then float freely


443
Walsh, B. D. I860* Observations on certain IT. A. Neuroptera, by H, Hagen,
M. D., of Koenigsberg, Prussia; translated from the original French
Mb. and published by permission of the author with notes and des
criptions of about twenty new II* A* species of Pseudoneuroptera*
?roc. Ent. Soc. Phila. 2; 169-179, 133-210.
1864* On the pupa of the Epheraerou3 genus Baotisca. Proo*
Snt. Soc. Phila. 3s 200-206, 1 text fig.
WllB, H* 3, Huxley, J. S., and Wells, 3* P* 1934* The Science of Life.
Doubleday, Doran and Co., Inc. Hew York.
Wodsedalek, J. E. 1912a. Palmens organ and its function in nymphs of
the Sphemoridae, Heptagenia interpunctata (Say) and Ecdyurus maculi-
pennis (V/alsh). Biol. Bull, s 25'SSVS', pis. 1-3.
- 1912b. Natural history and general behavior of the
Ephemeridae nymphs Heptagenia interpunctata (Say). Ann. Ent. Soo.
Amer. 5-6s 31-40.
ADDITIONS
Cory, Charles B. 1895. Hunting and Fishing in Florida, including a
Key to the Water Birds known to occur in the State. Estes and
Lauriat Co., Boston. Pp. 1-297. Numerous figures.
Harkness, W. J. K. 1941. The Limnology of Lake Mize, Florida. Florida
Academy of Sciences. In press.


261
Travers (1931a: 48-49) discussion of the habits of B* parolina
might well be applied to B* rogersi* The following account is an excerpt
from her papen "When at rest, it was quite characteristic for the last
three abdominal segments to be bent upward and the setae held up over the
body, reminding the observer of a squirrel* The nymphs walked or crawled
rather slowly, but swam quickly in spurts, usually in a straight line, vib
rating the setae rapidly* The legs were used little if any in the actual
process of swimming* The body of the insect did not undulate as it swam,
but rather it forged straight on like a tiny steamboat* Periods of several
minutes rest between spurts of swimming were not unusual* Nymphs clung
rather tightly to their stones, end some slight force had to be exerted to
remove one* When a stone with nymphs clinging to it was lifted from the
water, some of the nymphs let go their hold and swam off at once, while
others oould be lifted out of the water readily, still on the stone." This
acoount describes the behavior of the nymphs in an aquarium. The vibrating
motion of the tail as the nymphs swim is particularly interesting, for the
filaments move so rapidly that they almost seem to be revolving as a pro-
pellor; however, it is truly an up and down movement of the setae which
drives the insect through the water so rapidly*
On March 21, 1939, I noted a peculiar behavior in one of the nymphs
which I brougif back from northwest Florida* At 9:45 a* m*, I examined
the cage and found that one of the Baetisoas had crawled out of the water,
along the air tube, on to the flAOr, and then up the cloth side of the cage*
The nymph had progressed fourteen inches above the floor and, still alive,
was hanging on the oloth* Further examination showed that the animal was
quits immature not over two-thirds grown and yet had acted much as


300
species), and Caenis#
Wo studies have been made on the eoology of Worth Amerloan species
of Caenis¡ in fact, the species have been treated in scarcely any other
than a taxonomic way by American authors# Weedham has had more to say a-
bout the habits than anyone else, but his statements have been little
more than short comments on the habits of the nymphs# He (1935 180)
placed the nymphs in his category "The sprawlers amid the silt in still
waters."
The species of this genus are generally distributed throughout Worth
America, although there have been few records from the west# However,
C# aimulans is known from Wyoming and British Columbia, and I have collect
ed an unknown species from eastern Mexioo# It has been said that the
distribution of taxonomists can be plotted by studying the distribution
of species. This statement is very true in relation to mayflies and may
be illustrated by the fact that eight of the twelve described species of
Caenis are recorded from Wew York, while just across the border in Quebec
an additiqnal one is listed#
Phylogenetioally, Brachyoerous and Caenis form a closely knit unit.
The relations of these two genera to Trioorythodes have been discussed
under the latter genus# I agree with Spleth in his conclusion that "ap
parently the anoestral stock from which Caenis arose differentiated long
ago, and it has since then beoome highly specialized# In doing so it
has reached, both in the nymphal and adult stage, a condition superficially
but only superficially like that in Trioorythus [Tricorythodes]."
The high state of development of Caenis is evidenced by the complete
absence of hind wings# Diminution in size leading to loss of the hind


3S6
wading the stream one might easily walk almost across it without touching
the stream bed. With a few strokes of the dip net through this tangle of
vegetation, during the late winter, spring, or summer fifty to one hundred
nymphs are easily collected. In this mass, the nymphs seem to prefer the
more distal or free portion of the leaves and become less numerous near the
base of the plants*
The spring runs in the west-central and the north-central part of
Florida usually are quite similar to the Santa Fe River in having the great
growths of eel grass; however, near the head of the runs, where the springs
emerge, mayflies are very rarely found, but a short distance downstream,
they beoame noticeable. Their absence from the head of these runs may
possibly be explained by the fact that the water emerging from the ground
carries large amounts of calcium bicarbonate in solution which is deposited
as Calcium carbonate when the water reaches the surface, and this salt forms
a covering over the surfaces of the plants preventing the mayflies from
securing sufficient food to survive. Another explanation of the absonoe
of mayflies from the spring heads might be the lack of sufficient oxygen
in the water just after it emerges from its subterranean channels, and which,
as surface water, has not yet had time to become sufficiently oxygenated
for the maintenance of mayfly populations* Normally at the head of the
springs, the snail Goniabasis occurs in almost unbelievable numbers. I
have almost filled a dip net with them after taking a few strokes through
the eel grass; these might be a factor in restraining the introduction of
mayfly nymphs into spring heads*
Any slightly aoid stream in which there is some vegetation,either in
the middle or near shore, detritus, submerged logs, or leaf drift will or-


89
6 (5)
6
7 (S*)
7
8 (2*)
8'
9 (8)
9
10 (9)
round in northwestern Florida in tho npalaohioola river region
and westwards.
I'oxagenia weowa
Found in peninsular Florida
hexagenia orlando
Found in northwestern Florida.
Found in peninsular Florida.
exagenia bilineata
XTexagenia limnophila
dead strongly depressed; eyes dorsal. CJills present on abdomin
al segments 1-7; tuose on 7 reduced to mere filaments (see figs.
5 and 6); fimbrillar portion of gills 1-6 covered by protective
plate.
(iieptageninae) Stenenema (9)
Head not strongly depressed; eyes lateral.
(11)
dills on abdominal segments 1-6 truncate; seventh gills without
tracheae (see fig. 5).
(10)
Gills on abdominal segments 1-S pointed at a¡oex; seventh gills
with one large trachea (see fig. 6).
Stenonema proximua
Mo setae on crown .of maxillae; 6-8 pectinate spines on anterior
border (see fig 7). A yellow band across mesonotum at base of
wing pads of last instar nymphs*
Stenonema exiguum


68
in direction of trie wind*
These lakes show great variations in their aquatic vegetation; in
many, the succession is directly toward swamp conditions with extensive
development of cypress along the muddy shores; in others there is a distinct
development and sonation of marsh vegetation before the shallow water is
invaded by cypress or hardwood swamps." (Rogers, 193b).
(3) i-isappearing lakes certain large lakes in the northern part of Florida
go dry during periods of drought* Lake lamonia near Tallahassee is an
ideal example of a disappearing lake, and went completely dry in 1938.
There is one near Lake City which is said to go dry periodically, "once
every seven years." These lakes are shallow, and inmost respects are
similar to the silt-bottom lakes in having an abundant growth of water
hyacinths and a ring of cypress bordering them. Although at their maximum
extent the disappearing lakes are fairly large, they vary greatly in size
with seasonal fluctuation in depth*
Marshes
(l) Larshes are very oommon in peninsular Florida, particularly in the
lower regions* They may be very limited in extent or quite large according
to tne size of the origxnal basin, itony ponds and lakes have become con
verted into marshes, and many others are in the process of transition.
The water is shallow and vegetation extends throughout, growing very pro
fusely. The most predominant plants are emergent and include cat tail,
pickrel weed, maiden cane, saw grass, water lillies, 3martweed, and various
grasses* Submergent plants are quite prominent including Isnardia, G-lobi-
fora, Lyriophyllu, and many algae. The water is rather m.m during the


209
cussed the "snowflake mayfly", Tricorythodes minutus (as T explioatus)
in Utah and described flights miles long of these tiny insects. "They
flew as thick as snowflakes in a storm and were almost as white, and the
individuals were not much larger* Millions and millions of wings glanoing
in the light of the morning sun made scenes of great animation*" In
1905, 1908, and 1927, Needham briefly mentioned the habits of nymphs of
alleotu8, and In the last paper of expllcatus* Morgan (1911x115) also
briefly disoussed T* allectus.
Spieth (1933: 353-356) placed this genus in the same family with
Ephemerella, removing it frcan its classical position in the Caenidae*
Traver (1935: 631) disagreed with this view, considering Tricorythodes
to be an aberrant member of the Caeninaej however, she presented no eviden
ce but stated only that the venation of the imago is much nearer that of
the other members of the Caeninae than to Ephemerella* I believe that
Spieths ideas indicate the true relations of the genus* As he pointed
out, there is a difference in venation between Trioorythodes and Caenis;
the loss of hind wings with a corresponding increase in the anal area is
merely a parallel development in the two stocks, an example of convergent
evolution* The structure of the genitalia of the males seems to be one of
the strong points in Spieths arguement in both Trioorythodes and
Ephemerella, the forceps are three-segmented, while in Caenis and Braohy-
oercus there is but a single segment* Likewise, the penes of Tricorythodes
are similar to those of Ephemerella in that they are fused for about
three-fourths of their length and prolonged into a prominent, somewhat
conioal structurej in the other two genera the penes are united, broad and
plate-like considerably different from those of Tricorythodes Substan-


256
easily recognised." In many cases, nymphs of one group of a genus may be
readily identified while in another group of the same genus, there are
no really good separating characters#
Baetisca can be divided into two groups on the basis of the presence
cr absence of an orange or reddish coloration in the basal part of the
wings# The obesa group, in which there is no coloration, would include
B. obesa, B* laoustris, E. laurentina, and B. bajkcvi (the nymph is the
only form known); into the rube scene group would fall B# rubeseens, B*
Carolina, B. thompsone.e, and B# rogersi, all of which have seme coloration
in the basal portion of the wings# To some extent, the geographic distri
bution of these species bears out this division the former group is
predominantly northern, while the latter seems to show tendencies toward
a more southern distribution#
The genus Baetisoa is Nearctic, occurring in eastern North America,
except for B# ba.jkovi from eastern lanitoba; however, it has never before
been recorded from the Coastal Plain (unlesB Candy creek, Georgia is in
this province)#
According to Spieth (1935t 359) Baetisca seems to be a distinct entity
in the phylogenetic arrangement of mayflies# "Its ancestral stock must
have separated early from the remainder of the order." Baetisca, although
a highly specialized foim, exhibits eertain ancestral characters such as
a relatively primitive venation, a large hind wing, in the fore wings the
best developed cubito-anal area within the order, the forceps structure,
the similar lacinia mobiles, and the highly modified, but single, gills.
Needham considers Baetisca, along with Oreianthus, to be one of the isolated
remnants in the mayfly fauna of Worth America'


14
Eg, and R¡. plus H5J R4and Eg make up a single vein and the terminology
is used only to prevent confusion The media is represented by both its
primitive branches, the anterior media (lost in the Neopterygcta) and the
posterior media; and the cubitus is likewise represented by the anterior
and posterior cubituB The Ephemeroptera are the only modern inseots in
which both branches of the media presist The number of anal veins varies
from one to three according to the genus*
In the hind wings of the more primitive genera the venation is but little
modified from that of the fore wings; however, with the shortening of the
wing the area occupied by Rs lias become smaller and R3 has disappeared.
The genitalia of mayflies are likewise primitive Irams (1931: 41)
states that "a very primitive condition is found among Ephemeroptera, where
the penis lobes, instead of being fused to fora an aedeagus, are relatively
large and entirely free, with the parameros closely applied to them. A
styliger plate is borne on the terminal ond of the ninth sternum, and for
ceps arise from the posterior edge of the styliger plate The penes are
considered to arise from the ninth segment and protrude between the ninth
and tenth segments "The styliger plate of the mayflies is interpreted
by Crompton and Walker as representing coxites, which have fused together to
form a single struoture. This struoture, however, is separate from the
ninth sternite A parallel condition is to be found, acoording to 'Walker,
in the Phasmoidea and Acridoidea, except that in these groups the styli
are lacking. (Spieth, 1933; 73). The forceps of the male Ephemeroptera
are homologues cf styli, and in all mayfly genera, except Caenis, Brachy-
oerous, and Campsurus, are segmented. In the females, the oviducts open to
the outside or into a common vestibule formed as a fold of the thin membrane


250
derived from a common basic stock which split off from the ancestors of
Blast urns, Lept.ophlebia, and Paraleptophlebla.
Habrophlebiodes brunneipennls ms. name
TAXONOMY! Until very recently the Florida species of Habrophlebiodes
was thought to be H* betterdj however, examination of specimens of both
betteni and americana, identified by MoDuimough, immediately proved that
the Florida form was new. The most obvious distinctions between brunnei
pennls and the two more northern species lie in the wings. Those of brunnei
pennls are deep amber in color and have strong, dark venation, while the
wings of americana and betteni are oolorless, or almost so, and the venation
is weaker and paler. The genitalia of the three species are similar.
Nymphs of H. brunneipennls differ fresa those of the previously known
species of the genus in having spinules on tergite 6, as well as on 7-10.
It has hitherto been though that the absence of spinules from tergites
1-6 and their presence on 7-10 constituted one of the generic characters
of Habrophlebiodes.
DISTRIBUTION! In Florida, H brunneipennis is confined to the northern
part of the state, the southeasternmost limit of the known range being
Alachua county. Ab is usual with stream forms, even very tolerant ones,
brunneipennis is absent from the more or less stagnant waters in the low
lands of southern Florida, (ee n>a./> ?)
ECOLOGY! H. brunneipennis is found commonly in slow to moderately swift
flowing streams, where it dwells in the leaf debris. These streams are
usually of the sand-bottom type, but occasionally, the nymphs can be taken




129
county and Chicod Swamp In Pitt county, North Carolina. The last record
was published by the same author in 1937 when she recorded S. interpuno-
taturn from Wilson Lake, the location of which I have been unable to de
termine, and from North river near Tuscaloosa, Alabama* (See ^4i 7)'
ECOLOGY In many respeots, £>. proximum resembles S# smithae ecologically,
but its ecological valence seems to be of a lesser degree than that of the
latter species. One of the chief inhabitants of the larger streams of north-
central Florida, it is very rarely found in the smaller ones which support
large populations of smithae. Its habitat in these streams is identical
with that of smithae submerged logs, rocks, sticks, boards, eto. in
almost any part of the stream. The species seems to flourish to a much
greater extent in alkaline creeks which are of moderate dimensions, varying
from the size of Hatchet creek near Gainesville to the Santa Fe river.
Nymphs of proximum are also inhabitants of sand-bottom lakes, but
are eonfined tc the shore region where they can be found on the undersides
of boards, logs, stioks, or any other permanently submerged objeot which
might give the nymph a good foot hold and furnish a continuous food supply.
In the lakes, the insects confine themselves to that part which is entire
ly free of any silt and where there is a cleanly washed sand shore and beach.
There is little wave action or depositon of silt in this region. Vegeta
tion is almost lacking and suitable situations for the nymphs are not plenti
ful, consequently when a board is located on which there are nymphB, it will
usually have quite a number of individuals on it.
The stream associates of S* proximum are identical with those of
S. smithae; the lake associates include only two species of mayflies de
finitely and a third questionably. These are Ephemeralla trilineata,


411
Appalachians and gradual spreading into western Florida* (See s*?*/3 0
ECOLOGY: C. rubropiotum is an inhabitant of flowing water although the
current need not be rapid, rather, the species prefers slowly moving water.
Even though numerous Florida streams have been examined, only a few support
ed populations of this species in numbers sufficient to indicate that it
was a highly successful form in the creek. The first of these, from which
I have collected on three different occasions, is located 5.8 miles north
of Panama City in the panhandle of Florida. The creek is about fifteen
feet across and varies in depth from one to three feet. At the place
where collections were made there are two bridges, one for the highway,
the other for the railroad. Attached to the pilings supporting the bridges
were large clumps of a densely growing mossj this moss was also attached
to all other firmly anchored objects in the stream. The first time that
I collected here, the water was somewhat contaminated with masses of tar
which had been dumped as leftovers from road construction. Where the moss
occurred, the current was quite slow, the movement of the water soarcely
enough to cause the plants to stream out in the direction of the flow.
Farther upstream, it became shallower and the amount of moss was much less;
however, the creek soon became deeper and moss again beoame plentiful. Now,
another group of plants were evident, those typical of very slowly flowing
water where the movement is barely perceptible Persecaria, etc. On the
first date collected, the creek yielded only a few specimensj however,
the second collection included about twenty-five nymphs, and the third
provided over one hundred. On the last date, nymphs were by far more num
erous than on the previous collecting trips. In every case, the immatures
were taken from the moss,and,although the Persecaria was thoroughly examined,


HEXAGENIA Walsh
Hexagenia, described, by Benjamin Walsh in 1863, was one of the first
North American genere, to be considered as new. Taxonomically, the species
of the genus are at present in a somewhat confused state. Needham, in
1920, recognized only two "good and distinct species" in the eastern
United States a lowland form, H. bilineata, from lakes and rivers, and
an upland bog-stream species, H. recrvate. MoDunnough (1927 117) com
mented as follows concerning Needham's paper "With the above conclusions
I must most emphatically disagree* from a study of a large number of
dried specimens and further from personal observations on living material
(both subimagos and images) during the annual 'swarming* period at Sparrow
Lake, Ont., in the latter half of June, 1925, I am convinced that there
are a number of good speoies in this genus, closely related, it is true,
but well separable, partially on male genital characters and also on color
pattern of the abdomen, size of eyes, etx. none of these features varies
to any appreciable extent in any given speoies and Needhams so-called
intergradients are in reality good species." Traver (1931) accepted
McDunnough's speoies and described seven additional ones. In 1935 she
continued to use this classification, and added a new mid-western speoies
to the list* in 1937, she described Hexagenia kanuga from North Carolina.
As a result of Spieths (1940 327-330) study of Walker's types in the
British Museum, he reduced two of the previously described speoies, oooulta
and viridescens, to the status of subspecies of limbata. Probably when
the whole genus is intensively studied, a considerable number of the
other forms now having specific rank will be reduced to subspecies.*
1. A paper revising Hexagenia is in preparation by Dr. H. T. Spieth.


Rivers
56
Stagnant rivers #. 56
Slowly-flowing* deep rivers 57
Larger calcareous streams * 58
Ditches and puddles 59
Roadside ditches 59
Puddles
Ponds 60
Sink-hole ponds 61
Ponds with the surfaoe free of vegetation 61
Ponds with the surfaoe covered with vegetation 62
Fluctuating ponds 63
Temporary woods ponds 64
Sporadic ponds 64
Jerome sink . 65
Lakes 65
Sand-bottom lakes 65
Silt-bottom lakes .*.* 67
Disappearing lakes 68
larojpes* .. 68
The Everglades * 69
SWampS * 71
Cypress swamps * 71
Bayheads * 71
Springs 71
Acknowledgements


r


196
holmes Co. Candy creek (December 11, 1937, L. B., nymphs). Liberty Co,
Sweetwater creek (June 10, 1933, H, H. H., F, II. Y*, L. B., nymphsj
November 4, 1938, L. 3., nymphs; July 1, 1939, L. J. M. and L, B., nymphs;
December 1, 1939, L. E., nymphs); 10 miles south of River Junction (March
17, 1939, L. B,, nymphs). Okaloosa Co. -- Shoal river (December 11, 1937,
L. B., nymphs); Baggatt creek (April 4, 1338, H. H. H. and L. J. M., nymphs);
Nioeville (June 7, 1933, H, H. H., F. N. Y., L. B., nymphs). Santa Rosa
Co. 2 miles west of Llilton (April 4, 1938, H. H. H. and L. J. M., nymphs).
Alabama, Escambia Co. Perdido creek (June 3, 1940, II. H. II, and L. B.,
nymphs and adults).
Isonychia pictipes Traver
TAXONOMYi Traver described Isonychia pictipes from specimens collected
at the Apalachee and Alcova rivers in Georgia, basing her species on imaginal
characters such as the bicolored fore tibiae, pale venation, and small
size. The Florida specimens agree very well with her description, but
since she did not figure the male genitalia, there is still a modicum
of doubt as to the correctness of the determination* She did state that
the penes are very similar to those of I* sicca, but the drawings in the
"Biology of Mayflies" of the genitalia of this species are not particularly
dear. However, McDunnough figured the genitalia of I_. sicca in 1931,
and the Florida mayflies which I am calling pictipes agree fairly well with
his drawing. Traver did not rear this species and the nymph remains un
de soribed. I have been unable to differentiate nymphs which can be de
finitely classified as pictipes rather than as I. perdido. There seem
to be no really good diagnostic characters whioh will differentiate the


162
river (April 6, 1940, L. B*, nymphs, adults reared August 11, 1940} Feb
ruary 18, 1939, L B, nymphs, adults reared April 25} February 28, nymphs),
Gilchrist Co. Suwannee river (May 7, 1939, L. J M*, adults). Hills-
borotigh Co. Hillsboro river (June 18, 1939, L. J, M., adults). Holmes
Co, -- Sandy creek (December 14, 1939, L. B., nymph) This record is ques
tionable. Marion Co. 7iith.la.coo che e river (May 13, 1938, Ross Allen,
adults)} Oklawaha river (April 15, 1939, L. J. M., adults)} Withlaooo-
chee river (June 6, 1939, V/, M. McLane, adults).
Hexagenia bllineata (Say)
TAXONOMY* The taxonomy of H. bilineata is probably in better shape at
present than that of the majority of other species of Hexagenia, In 1920,
Needham decided to apply this name to "all variants of the species that
occupies the beds of our larger lakes and streams, MoDunnough (1927*
117) strongly disagreed with Needham and restored the species which the
latter had synonomyzed. Although many of the present species of Hexagenia
are considered by Spieth to be subspeoies of 1imbata and munda, bilineata
is so distinct that there can be no doubt as to its speoifio status,
H. bilineata is the most recent ephemerid find in Florida, Yfhile
collecting at a light in front of an ice house faoing the dammed up part
of Blue Springs creek near Marianna, a large mayfly was noted oiroling
about. With the aid of Dr, Horton Hobbs, the Insect was captured,and
I immediately recognized it as a species new for Florida, Before the
evening was over, nine individuals were taken, but unfortunately all were
females and thus the identification of the species, while almost certain,
still lacks the final verification of the male. These fit the description


282
lISTRIBUTIGN E* choctawhateh.ee Is the first species of the needhami
group to be recorded fr.m the Coastal Plain; it is* in fact, the first
to be recorded south of the mountains of North Carolina* Since records
for the species in Florida are so few, it is hazardous to draw any bther
than very tentative conclusion as to its distribution* E. choctawhatchee
is found as far eastwards as the tributaries of the Apalachicola river,
where it has been taken from a small stream in Gadsden county about one
or two miles from the river, and from Sweetwater creek, Liberty county,
at a point not over two miles distant from the parent stream* Other records
are from small streams in Okaloosa county that empty into Choct awhatchee
Bay* The distribution of this species seams to parallel that of E, apala-
chioola, although it has been taken on fewer occasions and in fewer places*
No reason for the eocentrioity of distribution shown by these two species
is apparent, for other species which are relatively new to the region have
managed to escape the hold of the Apalachicola drainage* (Sft //)
ECOLOGYi Clear, sand-bottom streams with a rather strong flow make an
ideal habitat for the majority of the stream forms of Florida. E* choctaw-
hat chee is no exception* In Sweetwater creek, the nymphs inhabit the same
root beds from whioh E. apalaohicola was taken, and in the other streams
they live either in the vegetation in more rapidly flowing water, or near
the shore amid the projecting roots* For a description of the streams in
Okaloosa county from whioh nymphs were taken, refer to Pseudooloeon bimaou-
latus (page )
The ephemerid companions of E* ohootawhatchee are the same as those
listed for E* apalaohicola.
SEASONSi With so few nymphs and no adults, it is impossible to be definite




408
arid algae covering the plants on which the mayflies live.
LIFE HISTORY; Nothing is known of the life history, but it is probably
no different from that of C. viridooularis.
DERIVATION OF THE SPECIES; C* hobbsi is probably derived from the same
stock which gave rise to C. rivulare, C_. bellum, and C_. ozburni. C* rivu-
lare is known only from Ohio, bel ham from southern Ontario and ozburni
from western Quebec and New York. It is, therefore, logical to assime
that C* hobbsi entered Florida, separating from a 3tock which was west
of the Appalachian mountains; that from this common stock in the central
United States, £# rivulare, 0. beiluni, and U. ozburni arose and went
north, Co hobbsi, after its origin, migrated southwards into Florida.
LuCALIIY iRiCOR^o; Alachua Co. Santa Fe river at Poe Springs (May 21,
1934, J. o. E., nymphs; March 12, 1933, L. 3., nymphs; Nay 14, 1938,
h. ii., nymphs; February 11, 1939, L. B., nymphs and adults; February
18, 1939, L. B., nymphs; March 25, 1939, L. B., nymphs and adults).
Hillsborough Co. Six-mile creek (Maroh 26, 1938, L. B., nymphs);
Hillsborough river (October 21, 1940, L. J. M., adults). Jackson Co.
12.2 miles southeast of Marianna (June 9, 1933, Ii. H. H., F. N* Y., L. B.,
nymphs). Marion Co. Hainbow Springs run (March 9, 1940, L. B,, nymphs).


6
certain Caruadian mayflies in 1930, and since has written two other papers
which are principally of a taxonomic nature* Hist most important contri
butions, however, are his excellent studies on the postembryonic develop
ment of mayfly nymphs and the effect of temperature on the distribution
of mayfly nymphs in a stream* At present, he is conducting quantitative
investigations on the insect fauna of streams with particular emphasis on
the ephemerids.
11. T* Spieth lias published papers of a taxonomic nature within the
last three years as well as studies on the coloration of mayflies and the
rearing of nymphs. His paper on "The Phylogeny of Some Mayfly Genera"
has been exceedingly useful to students of evolution and has aroused much
interest in phylogenetic work among the Ephemeropterists. At present, his
work is mostly taxonomio*
Jay R* Iraver is second only to Dr. MoDunnough in nuaber of species
she has desoribed* Her first taxonomic paper on the genus Hexagenia was
published in 1931, and since then numerous descriptions of new species have
appeared* Dr* Travers North Carolina work was particularly interesting
for it clearly showed just how poorly the fauna of the southeast is known*
One of her most important works is the taxonomic portion of "The Biology
of Mayflies." Her more reoent papers have dealt with exotic mayflies.
The present tendencies among the Ephemeropterists are still taxonomic
to a great extent, but phylogeny, distribution and ecological studies are
beginning to move into the foreground. Because of an awakening realization
of the fundamental importance of our natural resources, ecological studies
of the L'pheaneroptera, as well as of other aquatic insects, will probably
soon overshadow the present taxonomic research, but before such studies


SI
al differences, are really only seasonal forma of the sane species
I have been told by Drs Spieth and Lyman and Mr Jenkins, who have
worked in the Great Lakes region, that,as an example of this,Stenonema
tripunctatun shows seasonal variation in coloration exceptionally well
Dr* Traver has described several species differentiated from S tripunc-
tatum by ooloratlonal variations, but the other workers mentioned above,
through observations during the entire emergence period of the mayflies
of a particular region, have found that all of these are seasonal forms
cf the one speoies*
Size of adults, including both wing length and body length, has been
used to some extent for species determination; however, so many factors
modify 6ize that it is not considered a safe criterion by itself for the
erection of species Wing length within a population is much less variable
than is body length, for the latter is subject to shrinkage, elongation,
swelling, etc when the insect is killed There has been very little use
of relative proportions of wings fresa a taxonomic standpoint, but this
may be worthy of future study*
The families of mayflies as they are set forth in this paper appear
to be natural groupings, for the evidence from the adults is substantiated
by the structure of the immatures. Needham (1935* 208) states in this
order the struggle for existence has fallen largely upen the nymphs, which
are better equipped to meet competitors These show greater divergences
in adaptation to their several types of habitat These have differentiated
on lines of their own, independently of the adults, and tell their own
story* It goes without saying that out interpretations of nymphal and
adult evolution will, when correct, be in agreement On must corroborate


424
rather rare in the section of florida in which P# alachua occurs; nymphs
have, however, been taken from streams with this lower reading and from spring
runs which approaoh the higher pH. The immatures appear to thrive as Trail
in either the acid or alkaline water, but they do not occur at the heads
of springs, a pecularity shared in common vri.th all other species of Florida
mayflies. Tho possible explanation for their absence from such situations
has been discussed under the ecology of B. spinosus.
The stream which is the type locality of ?# alachua supports only
two other species of mayflies, Eaetis spinosus and B. australis, of which
B* spinosus is by far the most numerous* In the average sand-bottom streams,
other species taken along with alachua include Baetis spiethi, Blasturus
interned!us, Centroptilura viridooularis, Bphemerelia trilineata, Habrophle-
biodes brunnelpennia, Paraleptophlebia volitans, Stenonema smithae, and S*
exiguum. In addition to these, in the larger streams such as the Santa
Fe river, B. infcercalaris, Pseudocloeon parvulum, P. punctiventris, Centrop-
tilum hobbsi, Tricorybhodes albilineatus, and S proximum may be found.
SEASONSi Adults of P. alachua emerge throughout the year. Although adults
are known only for March, April, May, June, October, and November, nymphs
in their last instar were collected in February, November, and December,
and other nymphs ranging from very immature to last instar were collected
in November. The evidence is conclusive that disregard for seasons is
characteristic of P. alachua in Florida. This habit of year round emergence
is, of course, characteristic also of all the Baetinae in Florida.
HitBITS: The swimming habits of the members of this genus are all similar,
but because observations have been made more frequently on alaciase, than on
any of the others, they will be described for this species# Yihen the


163
of bilineata fairly -wall, but differ in minor details.
DISTRIBUTION! The species was originally described from Minnesota by Say.
Walsh recorded bilineata from Illinois, Eaton from Louisiana and Texas,
while McDunnough mentioned that it seems to^ be confined to the Mississippi
river and its tributaries. Additional localities given by Traver include
Fairport, Iow&j Lucedale, Mississippi? Waco, Texas? Knoxville, Tennessee?
St. Cloud, Minnesota? Cloverport and Lexington, Kentucky? Gadsden,
Tuscaloosa, a river between Birmingham and Decatur, and 'Wilson Lake at
Muscle Shoals, Alabama? Rome, Tombigbee river, Marietta,and Atlanta, Georgia.
The Florida specimens were taken from a tributary of the Chipla river
which in turn flows into the Apalachicola river* The Chattahoochee river
which flows through Atlanta is listed as a looality for H. bilineata, and
therefore it does not seem at all remarkable that the species should oocur
in other tributaries of the Apalachicola river drainage system. However,
it does appear rather strange that so large and striking a species had not
been found on my previous trips to west Florida, (iee
ECOLOGY* The nymphs are known to be bur rowers in the silt of the larger
lakes and streams. No inmaturos have been taken in Florida which I can
recognize as the nymph of bilineata. I rather suspect that, at the place
where the adults were collected, the nymphs live in the silt of the artifi
cial lake formed by the damming of Blue Springs Creek.
SEASONS* Nothing is known of the seasonal habits of the speoies in Florida,
except that the adults were taken in early June. From the information
available, the speoies elsewhere seems to be seasonal Eaton suggests
that it emerges from June (in the south from May) to September*
HABITS AND LIFE HISTORY: Needham (1920* 278-281) disoussed the habits,


269
recorded the species from the Coastal Plain of North Carolina at Lake
YTaceamaw, from Valle Crucis, North Carolina, and from Cooley Creek in
the northern part of Alabama*
Weet of the Apalachicola river there occurs a group of nymphs very
similar in appearance to those of this new species but with the spines
of the dorsum more erect and thinner and the body length somewhat lessj
however, I also have a nymph of trilineata from this side of the river.
The former individuals may be merely variants of the new 6peoies, or they
may represent E. doris in Florida. I hesitate to say that trilineata
occurs on the east side of the Apalachioola and doris on the west, for,
with their powers of flight, the adults should certainly be able to span
the river. Reoords of doris from Georgia also preclude the possibility of
such an abrupt break in distribution of the two species.
E* trilineata oocurs throughout the west-central, north-central, and
northwest portions of Florida as far as the Apalachicola river, and if
those speoimens which were taken west of the river are trilineata, then,
its range is extended to the western border of Mobile county, Alabama and
northward into Escambia county, Alabama. (Sre //f)
ECOLOGY! Eoologioally, the nymphs are confined to either flowing water
or lake margins where there is sufficient stirring of the water to supply
conditions favorable for development. Both silt-bottom and sand-bottom
creeks support populations of nymphs equally well, and in them the immatures
favor vegetation where the flow is not too rapid and where there may be
thiok algal growths. I have found many specimens entangled in masses of
Spirogira, but they were apparently well situated and seemed to be in good
health. Another favord habitat for more mature nymphs is among large masses


211
subimagal exwiae is left behind as a gray skin with crumpled sacs, the sole
remaining evidences of tlie subimaginal wings.
During January and February, emergence occurs anytime between 8:00 a.m.
and 4:00 p* m. with the height of transformation between 1:30 4:00 p,m*
After a quiescent period varying from eightee n and one-half to twenty-
four hours, the last molt occurs and the brilliant adult emerges its
thorax shiny black, its amber wings glistening* In February, this final
molt take3 place in the morning between 8:30 and 10:00 o'clock, reaching
its peak about 9:00-0:30.
'Ihe subimagos immediately after emergence are attracted to the more
strongly lighted sides of the cage and here sit waiting for the imaginal
melt. Alter many had died without molting, it was concluded that even
though the insects were sitting just over a pan of water, the atmosphere
must still be too dry* This was remedied by placing the mayflies under
a bell-jar with a watch glass filled with water and covered with cheese
cloth to p.- event the mayflies from wetting their wings or drowning in it*
dubimages introduced into this saturated air were quite successful in
molting, but even so, many failed to free their wings completely from
the subimagal skin* In transferring subimagos to the bell-jar, it is
advisable not to handle the wings, especially with forceps, for they are
very delicate and easily bruised; once bruised, the wings cannot be freed
normally,
Hany abnormalities occur in the wings of laboratory-reared adults,
particularly in the males. In some there are merely small holes scattered
through the middle of the wings, in others there are large breaks and in
still others, the distal half of the wing may be missing.


433
e
(19231 46) from the Rideau river, Ottawa, and since then it has been re
corded only once when Ide published his description of the immature.
The nymphs are distinct from all other Florida species in having a
median dark band on each of the caudal filaments and in the absence of
color from the seventh gills. The adults, if this species is punotiventris
should be easily distinguished by the absenoe of markings on the pale ab
dominal segments and by the presence on each abdominal sternite of a min
ute mid-ventral dot at the posterior margin.
DISTRIBUTION: The distribution of _P. punotiventris is exceedingly Interest
ing because there are no records of its occurrence in the intervening area
between Canada and Florida. In the latter region the nymphs have an
identical range with P. parvulum and have been taken from the same streamB.
During a short collecting trip into Georgia, I collected in a stream about
ten miles north of Maoon, and found nymphs there which are similar to those
of Florida, although the ventral dark dots are not evident on the abdomen.
Since, however, many of the Florida specimens do not have these dots, this
character does not seem of sufficient importance to separate the Georgia
specimens from P. punotiventris. (Jee
ECOLOGY* Ecologically, F. punotiventris is indistinguishable from P par
vulum.
SEASONS: Nymphs in the last instar have been collected in February, March,
April, and December. Even though there are wide gaps between collection
dates, these specimens do indicate that punotiventris emerges throughout
the year.
HABITS: Habits are similar to those of P. alachua.
LIFE HISTORY: Nothing is known of the life history, but it is probably


71
uWaiags
(1) Cypress swamps: Cypress swamps are very nunerous in Florida* and some
of these, suoh as the Big Cypress Swamp, occupy huge areas The cypress
swamps are formed in shallow depressions in flatwoods regions, and over
most of the year have standing water in them Not only does cypress occur
in them but black gum is also very common Herbaceous vegetation is, how
ever, limited though there may be clumps of Persicaria, Utricularia, and
some sphagnum along with masses of algae The water is usually tinted by
humic aoids, and its reaction is definitely acidic Depth of water varies
considerably, but is seldom over three or four feet.
(2) BayheadBi Bayheads are very similar to cypress swamps, but the vegeta
tion is muoh denser, and the bayheads usually form the headwaters of small
creeks The plants consist mostly of small trees and shrubs and also in
clude some oypress The other trees are principally sweet bay, black gun,
wax myrtle, red maple, loblolly bay, titi, Virginia willow, and dahoon
holly The growth of the shrubs is so dense as to be almost impenetrable
in places. Water stands in the depressions for the major part of the year,
and it is only during the very driest seasons that it entirely disappears
from the bayheads*
springs
"Most of the large springs of Florida are artesian* The water flowing
from them rises through deep, generally vertical holes in limestone, some
of which holes extend more than one hundred feet below sea level. At the
bottom these holes open into caverns, presumably nearly horizontal, through
which flow underground rivers.


28
branching in the case of trees." The highly modified hind livings are very-
useful in differentiating genera -Hithin the various subfamilies and,in many
oases, the shape of the costal angulation, the number of longitudinal veins,
and the general wing shape and relative proportions of these wings are
helpful even in distinguishing species.
The structure of male genitalia has been widely employed by taxonomists
throughout the field of entomology and even in the study of other animals*
These reproductive structures are particularly useful in the differentia
tion of ephemerid species, and have been widely applied, Many of our
present species have been established on genitalio differences alone, but
there are usually other characters which parallel such genitalio diver
gences. haoh genus has its own peculiar penial shape, and within the
genus there may be much variation. Lne of the best examples of this is
seen In Paraleptophlebia, where eaoh species has a distinctive type of
penes* The shape, number of segments, and relative proportions of the
forceps or claspers are also very useful in differentiating genera, and
in some cases species* The reproductive apparatus of the female mayfly
is so poorly developed externally that it is of no use taxonomioally,
except in those few genera which possess a rudimentary ovipositor*
Dr* Osgood biaith made a study of the eggs of a number of genera of
mayflies, and found that within a genus the sculpturing and accessory struc
tures are very uniform. From his study, he was able to construct a key to
the known eggs of Forth American mayflies, and this key has been incorpor
ated in "The Biology of Mayflies*"
The number of tarsal segments in the posterior pair of legs of adult
mayflies is a character which has proven useful as a familial differentiator*


18
found in the most primitive mayfliesj in the higher genera even the vein-
lets may he lost*
The hind wings indicate degree of specialization very clearly, for in
the Ephemeroptera there exists a whole series of species ranging from
those with well developed metathorado wings to those showing complete
absence of such structures* In certain of the highly specialized groups
the hind wings are reduced to tiny threadlike rudiments, sometimes so small
as to be difficult to find, and which could hardly be of any use as organs
of flight. The venation of these threadlike wings consists only of one to
throe longitudinal veins*
The form of the fore wings in the primitive genera of Ephemeroptera is
somevrhat triangular# With increasing specialization, they have become more
elongate and narrower, but in those genera with greatly reduoed hind wings
there is a tendency for the secondary development of a triangular wing with
a well developed anal angle, perhaps in compensation for the partial or
complete loss of the hind wing* The return to a triangular wing shape reaches
its culmination in the highly modified Caeninae, which completely laok
metathoracic wings*
Mot only is there a correlation between specialization and reduction
in size of the metathoracic wings, but closely linked with it, body size
likewise seems to have decreased* It is very likely that as wing size de
creased a diminution in body size was a natural consequence, or the reverse.
The amount of wing surfaoe for support of the insect being lessened, the
necessity for less body weight or an increase in wing surfaoe of the other
pair of wings was encountered. Both conditions have resulted. A diminution
of body size parallels the diminution in size of metathoraoio wings, with




1
THE MAYFLIES OF FLORIDA
Few orders of inseots have been so little studied in Florida as the
mayflies, or Ephemeroptera. The fragile, delicate-winged adults, requiring
special methods of collection and preservation, have not been favorite
objects of entomological study* and the same is true of the small and
often inoonspiouous aquatio nymphs of these insects. The objects of the
present study have been to determine what species occur in Florida, where
they are found, where and how they live, and as much as possible concern
ing their life histories* Four years have been devoted to this endeavor,
in the course of whioh muoh of the state has been examined, about forty
thousand specimens have been collected, nunerous speoies of mayflies have
been reared, and muoh eoological information has been obtained about the
group.
Although the Ephemeroptera include no enemies of agriculture, and
at first glance would appear to have little or no economic importance, such
an impression is altogether erroneous. The entire economy of aquatic life
is intimately bound up with the presence and abundance of mayflies, and it
has been demonstrated time and again that these insects, in both immature
and adult stages, constitute an important item in the diet of many species
of fish, or in that of other organisms that in turn are eaten by fish.
The words of Frison (1935t 284-285) apply with particular force to the
study of the epnemerids. He says "The insect life of our inland streams
[and lakes] affords a most interesting and profitable field for investiga
tion* and the sooner we learn to place and evaluate this fauna correctly,
tne sooner we will be in a position to formulate conclusions and generali-


153
of on orange or reddish color* Finally she settled down to the water and
was carried downstream about a foot* She then flew up again, but without
the eggs. This individual was captured. She was spent, and the tip of
the abdomen was still curved down, where it had fitted over the egg mass.
"Unfortunately no other females carrying egg masses were captured}
so I could not find out what happens to the mass when it is laid in water,
but the eggs are equipped with two very long coiled threads, which probably
adhere to the bottom and to other eggs.
"Mayflies belonging to this group are seldom seen in the early evening,
but may often be found later at lights. It therefore seems likely that
oviposition usually occurs after dark."
On April 19 while examining material that had been collected on April
6, several young Stenonema nymphs were found which were in either the first
or second instar* Although I em not by any means certain of the identifi
cation, I believe that they were the young of S.proximum* Because so few
specimens are available, I will not attempt to describe the development, bufc
there are oeirtain definite differences between these and the nymphs of
S* canadense as described by Ide (1935). The eggs from which these nymphs
hatched were probably brought into the laboratory attached to vegetation
which was used as aquarium plants. The vegetation was not examined when
first brought in, and it was not until two weeks later that, by accident,
I discovered young mayfly nymphs on a leaf. Even after such a short period
of time in the lab, the aquarium was literally teeming with organisms, es
pecially dipterous larvae, a few caddisfly larvae, young snails, etc. most
of which had apparently hatched in the laboratory. The mayflies had been
hatched long enough so that some had entered the second instar as demon-


36
flight, but in the areas where such flights occur, the emergence of those
species forming the large swarms is limited, to a short period. It has been
stated that those species which emerge over a long time the entire sum
mer vri.ll not form large flights, ajad from these accounts it would seem
that in size the flights resemble those of the Florida aphemerids.
The burrowing species,being more or less seasonal, emerge in great
numbers in Florida hut not in swarms ocmp&rable to those described as
occurring in the more northerly parts of the oountry. The lake species, in
particular, during their emergence period do form a conspicuous part of the
insect fauna in the Central Highlands of Florida, and at this time very
likely are Important in the food chains of lakes. The number of individuals
in the lakes approaches more closely the abundance characteristic of northern
regions, than does the number occurring in ary other situation in Florida.
However, the anta Fe river might perhaps compare favorably in this respect
with some northern streams.
Comparative ecology
Naturally, the eoological factors are the most important conditions
affecting the distribution of ephemerid species. As indicated above, those
habitats suitable for northern mayflies are, for the most part, absent in
Florida. Temperature is probably the most important single factor determin
ing the presenoe or absenoe of a species, and current is tied up very closely
with this. The great majority of mayflies are rheooolous, and, as Ide has
shown, the entire stream fauna is very much affeoted by thermal conditions.
This author has stated that the number of speoies inoreases downstream due
to the higher temperatures which prevail in the lower parts of the stream,
and the addition of speoies in this way is more rapid than the elimination




79
portion of penes rounded (see fig. 12).
Stenonema exlguum
11 (S') Hina wings absent. Fork of MA. very deep; posterior margins
of wings ciliate; no marginal intercalarles (see fig. 8). Eyes
of male simple, neither divided not grooved; widely separated.
Caeninae (12)
11' 4Hind wiiigs present or absent. Fork of MA. in fore wing normal
or detached basally; meirgin of wings ciliate or not; marginal
iuteroalaries present or absent in forewing (see fig. 14 and 15).
Eyes of male divided or simple in genera lacking hind wings.
(14)
12 (ll) Prosfcernura. twice as xvide as its length; fore coxae widely
separated; second antennal segment three times the length of
the basal segment.
Braohycerous maculatum
12* frostermm two to three times longer than broad; coxae much
closer together; second segment of antennae not much more than
twice as long as basal segment, (see fig. 8)
Caenis (13)
13 (12') Ctigmatie dark streaks on posterior tergites only. Head pale.
Thorax light brown. Short fine black 6treak on dorsal edge of
each femur.
Caenis hilaris
13 Stigmatic streaks present on anterior tergites. Head dark shaded.
Thorax light brown. Hind femora with a dark apical band.
Caenis diminuta


47
Caenis
hi laris
Caenis
sp*
Hexagenia
sp*
Ephemera
sp*
Undetermined
sp*
400 ft*,day
200 ft*,day
1
1
50 ft*, day
The above figures illustrate the fact that mayflies can be carried to
extreme heights, and, by means of horizontal air currents, doubtless to
considerable distances* Perhaps the greatest obstacles to be surmounted in
aerial distribution at great heights are the short adult life and the
necessity for the fertilized female to reaoh fresh water* Even when these
two obstacles are overcome, the chance of the oological factors being satis
factory are but slight; current-loving species could hardly develop in a
pond, and vice versa* The possiblility of distribution through wind currents
at great heights, therefore, seems to be somewhat remote, but the chance
nevertheless exists and must be considered*
From his study, Click concluded that size, weight, and bouyancy of an
insect bear direotly upon the height to which it may be carried by air
currents. He found that many species represented at high altitudes were
small insects* Temperature was undoubtedly the most important factor re
gulating the numbers of insects to be found in the air at any given time,
and he found that the optimum range was from 75 degrees to 79 degrees F*,
surface temperature*
Lr* Click points out that the intensity of air currents is a great
factor in the distribution and dispersal of inseots* most insects were
taken at the lower altitudes when the eurfaoe wind velocity was from five
to six miles per hour, and fewest when it was calm.
Viands at low altitudes are probably of importance in transporting
adult inseots from one region to another but their effedts are probably


39
Cenada and the northern states, all of those species have a rather limited
period of emergence during late spring and summer* but in Florida such is
not the case* Here* every one of the species common to both north and south
emerges throughout the year except during the cold spells, and mating
takes place at any the of the year, unless cold -weather is encountered,
when the insects become lethargic*
Although Spieth had no definite information on the point, he stated
rather accurately (1938cs 214) that "in the southern paid: of the United
States, the length of the emergence period of the group is much longer*
There seems to be no reason why in the tropics and subtropics there
should not be some species merging during each month of the year. The
greater part of Florida cannot be considered subtropical, yet Spieths
conjecture holds true for the whole area*
This author (Spieth, 1938cs 214) mates one statement whith which I
cannot agree* "Regardless of the time of emergence during the year, each
species has a definite limited period of emergence. In those species
which have more than one generation each year, naturally there is more
than one emergence period* Usually the period of emergence is relatively
short." In Florida, the period of emergence of the great majority of
species is not at all limited, although there may be many broods emerging
during the year* I do not believe that results obtained in the north, upon
which Spieth based his conclusions, can be accurately applied to the species
inhabiting Florida.
Not only are many of the mayflies non-seasonal in Florida, but this
has beer, found true of otter groups of animals as well. Professor J. S*
Rogers has told me that the life histories of many craneflies are not


233
that the food materials are probably obtained by scraping the surface of
dead leaves; not only organic substances were in the enteren, but also
small grains of quartz sand.
Although the gills are well tracheated, single, and exposed, the
nymphs keep them in constant motion. T/ihen the nymphs are at rest, the gills
are held stiffly out from the body at a forty-five degree angle with the
plane of the dorsum, and slowly waved forward and backward. When swimming,
however, the gills are appressed against the abdomen and do not assist in
this activity.
As typical Leptophlebines, these nymphs are rather awkward swimmers,
their most efficient and usual movements are crawling ones as would be ex
pected from their choice of habitat. Swimming requires a great amount of
exertion and is not at all natural in this genus; the swimming movements
can in no way compare in gracefulness with the darting of the Baetinae.
The nymphs swim by a series of undulatory motions, the wave beginning
cephalically and traveling to the tails which are depressed or raised as
a unit. However, the caudal filaments aid very little in propelling the
nymph; almost naked, they are little more than long hairs trailing behind.
Lepfcophlebine nymphs can be recognised immediately by their movements
on the surface of a white enameled pan. When the water is drained away
from them, the insects crawl in the wake of the liquid, vigorously wiggling
the abdomen and tails from side to side in a sort of scrambling effort
to hide themselves beneath any convenient object.
As in many of the Ephemeroptera, brunnelpennis exhibits a definite
negative phototropiem in the nymphal stage and a reversal of this condition
in the subimagal and imagal stages. Eheotroplsm is also exhibited by the


270
of leaf drift in slow water A third important situation is the submerged
logs, boards, sticks and other rather solid materials where the nymphs
hide in the cracks and crevices, beneath the bark, or in any other protected
portion Nymphs have been found most abundantly at Hatchet creek near
Gainesville. This stream is a moderately flowing sand-bottom, acid creek
draining flatwoodsj in the area most thoroughly collected, a portion of
the stream has been dredged and here it becomes rather deep and slow flow
ing Near the shore of the dredged area in shallow xfater, there are dense
growths of parrot's feather (Myriophyllum) where the flow of water is negli
gible Sphemerella nymphs are quite common during the fall and spring among
the Myriophyllum stems and leaves which are submerged, but they are also
frequently found in the other vegetation near shore where the water is not
too swift*
Bphemerella trilineata nymphs inhabit only those lakes with sandy
shores and they seldom venture into depths greater than three feet Here,
they are not found on the vegetation and among the smaller debris as in
streams, but are confined to submerged sticks, boards, logs, and other large
objects partially buried in the sand On these, they live only on the under
surfaces in company with Stenonema proximut and Choroterpes hubbelli
Suitable situations in the lakes are so much scarcer than in streams that
lacustrine populations are correspondingly smaller
The streams in whioh the nymphs of this species live drain flativoods
and are usually acid or circum-neutralj the water is nearly always tinted
Nymphs have not been taken from spring runB nor any other basic streams.
The mayfly associates are the same as those listed for Choroterpes hubbelli
in the sand-bottom streams; its lake associates have been listed above


-. .


354
SEASONS A* ephipplatus occurs in Hatchet Creek near Gainesville, but the
species has been taken only intermittently on many collecting trips to the
stream, consequently seasonal data are not very complete for it, A study
of the specimens from west Florida and from Hatohet Creek indicates that
the species emerges throughout the year* however, adults in my collection
were taken only in Maroh, April, May, June, and October* Nymphs in their
last instar were collected in August and September, while half-grown speci
mens are known for April, May, and June and very immature nymphs for June*
While these latter specimens seem to indicate that emergence must occur
during the winter and fall, it is due only to lack of collecting that I
have no definite information for the other months of the year* The type
specimens from Georgia were taken on June 1 and August 3*
HABITS Just as the Baetis species, ephlppiatus is a rapid swimmer, a grace
ful clinger, and a less adept orawler* The nymphs cling to vegetation with
the head facing upstream, the tails waving as the current swings the body
frcm side to side* Slowly, they move about over their supports grazing on
the materials covering eht plants, occasionally darting to another plant,
but always facing upstream. On this vegetation, the nymphs seldom go deep,
but remain mostly near the outer leaves and stems away from accumulations
of silt and detritus*
The body of the nymphs is quite rounded and when they are placed in a
pan or dish, they usually fall onto their side and can move only by flick
ing the abdomen* If the insect falls on its belly surface, it can crawl
but not rapidly like the Leptophlebines.
Examination of the alimentary canal of west Florida speoimnes indicates
that the nymphs feed predominantly on filamentous alg .e, but an occasional


374
southern county line (March 27, 1938, H H* H, L. J. M L. B, nymphs),
Hillsborough Co 2 miles west of Alafia (March 26, 1938, H H IT*, L. J,
M,, L B, nymphs); Little Fish-hawk creek (March 26, 1938, H, H H, L. J.
M, L. B, nymphs); Bell Creek (March 26, 1938, H. H, H, L. J M, L B,
nymphs); Six-mile creek (March 26, 1938, H, H II,, L, J, M*, L* B, nymphs
and adults); Hillsborough river (October 21, 1940, L, J, M, adults).
Holmes Co, Sandy creek (December 11, 1937, L* B, nymphs; July 2, 1939,
L J, M, and L B, adults; December 14, 1939, L, B*, nymphs), Jackson
Co, 3,6 miles north of Altha (December 10, 1937, L B, nymphs; July 1,
1939, L* J, M, and L, B, nymphs); Florida caverns state park (December 2,
1939, H, H, H, and L. B, nymphs), Jefferson Co, Drifto.n (February 5,
1938, H, K. H F. N, Y., L, B, nymphs) Leon Co 112 mxles west of
Tallahassee (March IS, 1939, L. B, nymphs); 16,9 miles west of Tallahassee
(March 17, 1939, L, B., nymphs) Liberty Co, 10 miles south of River
Junction (March W, 1939, J, S, R, H# H, H,, F, N, Y*, L, B, nymphs);
near Oohlocknee river (March 16, 1939, L, B,, nymphs); 4,5 miles from the
turnoff to Torreya State Park (June 10, 1938, H* II* H, F, H, Y,, L, B.,
nymphs); Hosford (March 17, 1939, L, B,, nymphs)j Little Sweetwater Branch
(December 10, 1937, L, B,, nymphs; June 10, 1938, L, B, adults); Sweet
water creek (November 4, 1938, L, B,, nymphs; July 1, 1939, L* J, M, and
L, B, nymphs), Madison Co, 43 miles east of Jefferson Co, line (Feb
ruary 5, 1938, L, B, nymphs), Marion Co# Withlacoochee river (March
25, 1938, L, B,, nymphs), Nassau Co, 19 miles north of Duval county line
(August 28, 1938, H, H, H, nymphs), Okaloosa Co, 5,1 miles west of
county line (June 7, 1938, H, H, H,, F, N, Y, L* B,, nymphs; May 31, 1940,
H, II, H, and L. B, nymphs); Niceville (June 7, 1938, H. II H,, F, N, Y. ,


80
14 (11)
14'
15(14)
15
16 (15)
16
17 (16)
of fore wings ends in outer margin} no cubital intercalarles}
s tf;"'*'
basal third of fore wing and basal four-fifths of hind wing
suffused with orange-brown (see fig. 13). Eyes of male not
divided.
(faetiscinae) Eaetisca rogersi
of fore wing ends in hind margin; cubital intercalarles
present (see fig. 14). Eyes of male divided, marked with a
distinct band, or simple.
(15)
MAg and ilPg of fore wings detached basally from their respective
i
stems, (see fig. 15). Hind wings much reduced in size and
venation, or they may be entirely wanting (see fig. 16). Eyes
of male turbinate.
Baetinae (27)
MAg and iifg of fore wings normal, attached basally (see fig* 14);
or lPg may be detached basally, but this is paralleled with loss
of hind wings. Eyes of male not as above. If hind wings present,
(<
venation of metathoracic wings not greatly reduced (see fig. 17).
(16)
Tail3 two.
(24)
Tails three.
(17)
Two short intercalarles in fore wing between IMP and MPg and
between LPg and CuA. Male forceps with a single terminal seg
ment (see figs. 14 and 18).
Ephemerellinae
(18)


108
For speed, the swimming of S. smithae cannot compare with the rapidity
of its crawling movements under water It Is almost impossible to sieze
the nymphs with forceps without injury when they are in this situation.
It is obvious that this latter ability should naturally be greatly ac
centuated over the ability to swim as one of its adaptations for a cling
ing life.
A strong thigmotactio reaction is one of the most characteristic
behaviors of Stenonema nymphs. The slightest contact with an object in the
water will cause the nymph to immediately fasten its claws and hold on "for
dear life." Of course, such tenacity is necessary when they are exposed to
the strong currents which, at times, must sweep under rooks in mid-stream.
Even though the nymphs may be taken from almost stagnant water, thigmotrop-
ism in them is as strongly developed as in nymphs in the swiftest water.
The reaction is so pronounced that if several nymphs are placed in a dish
of water with nothing to which they might cling, they will form a clump
and will remain clumped until some more attractive object is put in with
them. The tenacity of the nymphs is shown in their reluctance to release
their hold when the object to which they are clinging is lifted from the
water. An inexperienced collector frequently injures the nymphs by attempt
ing to pull instead of lifting the insects from the support to which they
are holding.
Wodsedalek (I912i 35) found in experimenting with nymphs of S. inter-
punctatum that the desire for contact is so strong that they are not fully
satisfied until even the dorsum is in contact with some object. "Two long
brioks were placed one over the other in a basin of water and between them
small pebbles varying in size so that the space gradually varied in thick-


143
absent, and only the more tolerant of pond forms thrive in them* Lake
Newnan has a bottom deposit of silt which is thick, loose, and fluffy,
and in which very few organisms exist. The tremendous amount of silt
apparently makes it impossible for those bottom organisms requiring a
moderate supply of oxygen to remain alive, buried as they would be by
the layer of decaying organic materials on top of them. The bottom
reoeives a continuous and large supply of dead vegetation, since lakes
of this type have many floating plants water hyacinths, and to a
lesser extent water lettuce, which drift about at the meroy of the winds
and sometimes an abundance of spatterdook extending out to a depth of
as muoh as Beven feet.
Iramatures have not been collected from the lakes of the southern
part of the Central Highlands, but adults from these lakes are not
different from those of the Northern part of this region. A superficial
examination of the southern lakes indicates that they are identical with
the sand-bottom type of the more northern area.
The lake bottoms must constitute an ideal habitat beoause enormous
numbers of individuals live in them as burrowers. Various people have
reported that when H. limnophila is emerging, the adults become pests,
and that they pile up under street lights and have to be swept from the
streets. I have seen them out in suoh numbers that the sides of a bath
house were almost hidden by the inseotsj nearly every blade of grass
supported several individuals. The mayflies, when disturbed, fluttered
upwards in great masses, to settle on the nearest support even dinging
to body and clothing. In every depression on the sand-beach, dead may
flies were accumulated several layers deep. Along the edge of the water,


430
identical with those figured by this latter authori however, since P*
alaohua also shows faintly annulate caudal filaments, this banding can
no longer be considered unique*
DISTRIBUTION* Pseudocloeon parvulum is known from the type locality listed
above and from Milk river, Alberta, the Peche river, Wakefield, P. Q., and
in the south nymphs and adults have been collected from a limited area
in Florida* This latter region stretches from Alaohua county to Liberty
county, where it includes the tributaries of the Apalachicola river on
the eastern side of the stream* Here, the distribution is somewhat spotty
and rather difficult to explain, for, although the streams on the west
side of the Apalachicola do not differ materially from those on the east
side of the river, the nymphs do not appear in any of my collections from
this region* Likewise the absence of the nymphs from Hillsborough county
seems unusual, since the conditions in the Hillsborough river are very
similar to those in the Santa Fe. (ee s-),
ECOLOGY* Nymphs have been found most abundantly in the basio Santa Fe
river* The species is known from only three other localities* In the Santa
Fe, the nymphs live in the swifter parts of the stream on the Yallisneria
whioh grows here so very thickly. The river has been previously described*
and it need only be said that the nymphs inhabit the distal portions of the
leaves whioh float free in the current* Only rarely have the nymphs been
found on the rocks whioh are strewn here and there over the stream bed,
but this absence may be explained by the mats of Fontinalis which entirely
cover the upper surfaces of the stones* An occasional immature may some
times be found on the undersides or in crevices of the rooks, but they are,
by far, more numerous on the plants*




317
L* B., nymphs)} 3.6 miles north of Altha (July 1, 1939, L. B*, nymphs)j
Blue Springe Creek near Marianna (April 13, 1935, nymphs; June 9, 1938,
L* B*, nymphs; July 1, 1939, L. B, adults; Deoeanber 1, 1939, adults,
H* H. H*, W* MoLane, L* B*; June 5, 1940, L* B*, adults). Lain Co*
Tavares (March 23, 1936, F. N* Y*, adults); Crows Bluff on St* Johns
River (September 12, 1938, J* R* Preer, nymphs); Umatilla (October 2,
1938, F* N* Y*, nymphs)* Leon Co* 13*8 miles west of Tallahassee
(June 6, 1938, L* B*, nymphs and adults)* Liberty Co* Hosford (March
17, 1939, F* N* Y** nymphs); near Oohlooknee River (March 16, 1939, F* N*
Y*, nymphs)* Madison Co* 5*9 miles west of Madison (February 5, 1938,
L. B*, nymphs); 11*3 miles west of Madison (February 5, 1938, L. B*,
nymphs)* Marion Co* - Ocala National Forest (February 12, 1938, L* B*,
nymphs and adultsj Maroh 19, 1938, S* Spurr, nymphs); Eureka (February
12, 1938, L* B*, nymphs); Lake Bryant (April 15, 1938, J* S* R*, nymphs);
Juniper Springs (September 1, 1938, T* H* Hubbell & J. J* Friauf, adults)*
Martin Co* Stuart (May 1 ?, J* McDuimough, reoorded in 1931)* Nassau
Co* Gross (December 19, 1939, H* H* H*, nymphs)* Orange Co* Lake
Ola (April 4, 1939, F* N* Y*, nymphs); Orlando (November 10, 1938, H. H*
H*, adults)* Pasco Co* * 20 miles north of Tampa (March 25, 1939, L* B*,
nymphs)* Putnam Co, 30 miles east of Gainesville (October 2, 1937, L.
B*, adults); 1*2 miles north of Palatka (October 2, 1937, L* B*, nymphs);
3 miles north of Palatka (October 2, 1937, L* B*, nymphs); Palatka at
bridge over St* Johns River (October 16, 1940, H* H* H*, adults); Welaka
(July 5, 1939, A. M* Laessle, adults; July 16, 1939, 0* E* Frye, adults;
October 12, 1939, E* L. Pierce, adults; October 19, 1940, W. MoLane, adults)*
St Johns Co* At Bwy* #48(April 23, 1938, F. N* Y*, nymphs)* Taylor


151
Hexagenia warn Traver
TAXONOMY* Hexagenia weewa was described in the adult form by Traver in
1931 The species appeared in the literature again in 1935 -when it was
redesoribed by Traver in "The Biology of Mayflies"
At the same time that Traver described weewa, she also described two
Hexagenia nymphs from Florida (Ros 4 and 6)* one from Gainesville and
one from Gainesville and Torreya Very likely the Torreya nymph is the
inanature of H weewa and the Gainesville nymphs are orlando} however,
her allocation of the nymphs from Torreya and from Gainesville to the same
species seems to help clinch the argument that the differences between the
forms called weewa and those called orlando are not specific* Studies of
adults from west Florida and from the Gainesville area show that male adults
from the two regions are almost identical* Examination of females from
these two areas does reveal a color difference, the mid-dorsal line on
the adbomen of weewa is not as prominent as that on orlandoj furthermore,
the oblique lateral lines on the dorsum of the abdomen of weewa are weaker
than the corresponding ones on orlando j and the body of weewa is a bright
canary-yellow while that of orlando is darker The west Florida epeoimens
are, on the average, somewhat larger than those from east Florida* All
in all, the similarity of these two species is so great that I am inclined
*
to consider them as one, but until more material is studied it would per
haps be beet to leave them at their present status.
DISTRIBUTION! Nymphs have been collected from the streams of the Talla
hassee Hills region whioh I am placing as weewa, but with reservations.
H. weewa immatures are known from the tributaries of the Apalaohicola river,
both on the eastern and western sides of this stream} nymphs and adults


414
plotum The latter author described the flight of" the adults as follows:
"numerous at Station Island [Georgian Bay] about July 10th, flying in small
smarms along the shore at a height of from 10 to 15 feet They appeared
about 7:45 in the evening." Ide (1930) found the adults swarming in late
evening at Lake Nipissing. The single, female which mas taken flew into the
automobile as me stopped tc collect at a stream in northwest Florida
DERIVATION OF THE SPECIES: C. rubropictum very likely originated in the
north all of its affinities being with northern species and has
moved southward through the western Appalachians* finally penetrating into
the streams of northwest Florida via the Mobile and Apalachicola drainage
systems
LOCALITY RECORDS: Bay Co. 56 miles north of Panama City (June 8 1938,
E H E, F* N. Y, L. B, nymphs; November 5, 1938, L. B, nymphs; May-
30, 1940, H* H H. and L B, nymphs); Pine Log creek (May 31, 1940, H
H* H* and L. B, nymphs) Holmes Co. Sandy Creek (July 2, 1939, L. J.
M, L. B, adult). Jackson Co. Florida Caverns State Park (December 2,
1939, L. B., nymphs). Wakulla Co. Wakulla Springs run (May 29, 1940,
H. H. H. and L. D., nymphs). Walton Cc. 2.1 miles west of Walton county
line (May 31, 1940, II* H. H. and L. E*, nymphs). Yiashington Co.
Holmes creek (June 9, 1938, H. H* K,, F. N Y., L. B., nymphs; July 2,
1939, L. J. M. and L* B, nymphs).
Cloeon nyssa ms name
TAXONOMY: Without doubt, the four nymphs of this species in my collection
fall into the Cloeon-Neooloeon complex. Final decision as to whether the
the speoies belongs in Cloeon or Neooloeon must await the discovery of the


204
and granis from austrlnus and oollinus (bearing the "hooded type of penes)
by the relative length of the reflexed spurs. In the former group, these
spurs extend anteriorly from the distal end of the penes to the base of
the notch between the paired penes, while in the latter, the spurs are
relatively shorter. Absence of a brown cloud in the fore wing or absence
of a brown stain in the stignatic area of this wing distinguish interme-
dius and granis from the remaining species of the genus. Finally, granis
is separated from intermedius by its larger size and short middle caudal
filament* The median tail in granis is but one-half the length of the
laterals, while in intermedius the mid-filament is two-thirds the length
of the outer ones.
DISTRIBUTION! On the basis of genitalia, intermedius is seen to be most
closely related to grandis. The distribution of these two species bears
out this conelusion as to their relationship, both having been recorded
only from North Carolina (previous to my work in Florida)j grandis from
the Piedmont, intermedius from the Coastal Plain* Traver (1935538)
records intermedius from "Braden Co.", North Carolinaj this is obviously
a misprint and should read Bladen Co.
Continuing southward into Florida, B. intermedius is rather widely
distributed over the state; in fact, it is found from the eastern portion
to the western borders in the continental area. In the peninsular region,
this species is much more sporadic in occurrence, but this "spotty" dis
tribution is entirely the result of eoologioal factors.
The absence of records of B. intermedius from South Carolina and
Georgia is almost certainly to be explained by lack of collecting. Pro
fessor Fattig of Emory University has oolleoted a large number of Georgia


280
rather slow growth during the winter months or perhaps a long egg period.
The gradation in size of nymphs may be explained by a very rapid growth
period allowing several generations per year. The life span would then be
approximately six to eight months. From the small amount of material at
hand, it is impossible to make any deductions as to the peak of emergence.
No nymphs were found in any of the streams of northwest Florida during
November. 1938, and December 1937 and 1939.
HABITSi The difficulties of transporting live nymphs of stream mayflies
from West Florida to Gainesville are very great, and while this has been
done successfully with two species, no nymphs of E. apalaohicola survived
the trip. The nymphs live in well-protected places where there is usually
some aocimulation of silt, and are very difficult to see when taken up along
with debris. In a small stream in Alabama., one speoimen was colleoted
from the moss covering the upper side of a large rock which was near the
middle of an artificial rapids below a dam. Traver says of the habits
of the related defioiens in. North Carolina (l932t 177) nBoth here and in
the Ooona Lufty River, these nymphs were found among the moss and other
plant growht which thickly covered the tops of all the larger rocks, and
they could be seen only after the rock had been left out of water for some
minutes, when they began to scramble about."
In the field young E. apalachioola nymphs may easily be confused
with those of Oreianthus or Trioorythodes. Members of all three of these
genera, when taken from the water, will walk slowly about flicking the
caudal filaments over the dorsum. Ephemeralla, however, is easily dis
tinguished from Oreianthus by its lack of gill covers and from Trioorythodes
by the same characters.


407
In Jackson county, two nymphs were taken from a stream, with a pH of
7*8, which completely lacked vegetation in the flowing portions* These
immatures were found clinging to submerged logs in the swiftest part
of the creek. Farther west in Florida, along the Choctawhatchee Bay re
gion, there are a number of small creeks with dense mats of Vallisneria,
Sagittaria, etc. in mid-stream, but the species was found to be entirely
absent from them* These streams are all definitely acidic with a pH not
much over 3*0. It would seem, therefore, that C* hobbsi is quite sensitive
to conditions of alkalinity, and chat this sensitivity is probably the
limiting factor in the distribution of the species*
The ephemerid associates of G* hobbsi are the same as those listed
for C* viridocularis in the Santa Fe river* In another stream, they
were taken in company with Isonyonia perdido and I* pictipes.
SEASONS: From the paucity of records, little can be said about the sea
sonal occurrence of C* hobbsi* Adults have been recorded in February,
Maroh, and April and mature nymphs were taken in February, March, May,
and June* One young nymph was collected in march, and probably indicates
a late summer emergence* Very likely, emergence occurs throughout the
year, but due to the scarcity of individuals and their absenoe from acidio
streams, I have been unable to secure sufficient evidence to make this
statement without reservations*
HABITS: Examination of the contents of the alimentary tract of one of
the few nymphs in the collection from the Santa Fe river showed the food
to consist almost exclusively of idatams with a few strands of algae inter
spersed in the material* From observations on C* viridocularis, both speoies
of this genus in Florida might be considered as grazers on the diatoms


401
Although all of these species do not typically occupy the identical habitats
of C. viridocularis, individuals of any one of them can, at times, be
found with this species* In the Santa Fe river, a different group of may
flies forms part of the biocenosisi Centroptilum hobbsi, Baetis spir.osus,
B* interoalaris, Pseudocloeon parvulum, P. punctiventrls, P. alachua,
Stenonema smithae, S* exiguum, S proximum, and Trloorythodes albllineatus*
These speoies are, in general also associated with C. viridocularis in
other Florida waters* Of course, there are the other usual irnrertebrate
forms present in varying numbers and kinds according to the situation.
SEASONS* The evidenoe is not conclusive, bub, nevertheless, points clearly
toward a year round emergence of £ viridocularis* Adults were taken or
reared only in April, May, June, July, and August, but there is also in my
collection a mature nymph taken in October* In addition, very young nymphs
were collected in March, July, and December, and half-grown specimens are
known for February, May, June, and July. The young nymphs of March and
July might very well emerge during the fall and winter and the half-grown
nymphs of May, June,and July might do likewise* Since related genera show
a disregard for seasonal emergence, and with such strong evidence as given
above, it does not seem unlikely that transformation occurs in all months
of the year*
HABITS* The nymphs of Centroptilum are very easy to distinguish from other
mayfly nymphs (except Cloeon) in the field* '/hen the live nymph is placed
in water, the tails are not held straight oaudad as in Baetis, but the tips
are depressed slightly; also a brown band is usually prominent on the
caudal filaments of mayflies likely to be confused with the nymphs of Cen
troptilum* In addition, the long hairs on the tails of Centroptilun are


436
the Choctawhatchee Bay region have populations of these nymphs living
in Vallisneria not more than one hundred yards from the salt water. In
other sand-bottom streams, where there is no eel grass, the nymphs live
olose to shore on the vegetation or any other materials which are per
manently anchored in the flowing water. The imraatures do not seem to occur
as commonly on submerged logs, sticks, etc. as they do cn the vegetation
in contradistinction to P. alachua. Nymphs have not been found in the
riffles of the west Florida oreeks, but since pebbly riffles are very
rare in these streams relatively few have been examined. In one small
creek, about three or four inches in depth, the bottom was covered with
an algal growth and here, in midstream, several P. bimaoulatus nymphs were
found.
The creeks from which nymphs were collected ranged in pH from f,,0
to 7.6, but the immatures appeared to be more common in the acid streams;
however, this may not be significant,for in many of the west Florida acidic
streams, as well as the basic, vegetation is quite dense.
Mayflies which have been found associated with P. bimaoulatus include
Baetis spinosus, B# australis, B. spiethi, B. interoalaris, Acentrella
ephippiatus, A. propinquus, Caenis hilaris, Chorcterpes hubbelli, Paralepto-
phlebia volitans, Ephemerella choctawhatchee, E. apalachicola, E* trilineata,
E. hirsuta, Baetisca rogersi, Iiabrophlebiodes brunneipennls, Tricorythodes
albilineatus, btenonema sra.ithae, S. proximum, and S* exiguum.
The adults we re all taken at light near atreams. No nymphs were collected
from the stream where the adult male was taken, but the females, with which
I am associating the male, were collected at Perdido creek where the nymphs
were plentiful in dense growths of Vallisneria and Potomogeton.


337
(usually); an insufficiency of oxygen due to the absence of submergent
vegetationj lack of food materials! or# lack of suitable refuges* Not
only mayflies find it difficult to live in this sort of place, but the
normal pond margin inhabitants are also missing. Sink-hole ponds and lakes
in which the margins are completely or even only occasionally covered by
t
water hyaoinths, usually do not support £ £ minor nymphs, probably for the
same reasons that they are absent from the sink-hole ponds.
The ditches# ponds# swamps, etc. which Calllbaetls nymphs inhabit
may range from a very acid condition to a very basic one. Nymphs have been
collected from a Fontederia marsh in which the pH (oolor-metric measurement)
was lower than 4.0# below the lowest range of the instrunentj in a lake
(Bivens Arm) choked with vegetation# principally ffiyriophyllum, nymphs were
common at a pH above 10.0 (glass-electrode measurement). Not only are the
nymphs very tolerant to the acidity or basicity of the water, but also to
the degree of freshness. In the summer of 1939, Mr. Jack Russell, while
working on salt-marsh mosquitoes near New Smyrna, frequently took mayfly
nymphs along with the mosquito larvae. However# he neglected saving them
(later he collected a few), but he did notice that they occurred in water
which ranged from fresh to definitely brackish. On June 30, one adult came
to his light at Coronado Beach; since this Island is some distance from
the mainland and the water there is brackish, the nymphs must have developed
in the definitely salt water. Further, I collected immatures from canals
in the oity of Miami not more than one or two miles from Bisoayne Bay and
subsequently I have learned that seme of these almost stagnant canals are
brackish, particularly so at high tide. I have been told that Biscayne
Bay during the early part of the twentibhh century was, in places, brackish


511
The above figures indicate that the fall and winter broods hatch
much more rapidly than do those of the spring. Wo eggs were hatched
during the summer* time required for hatching in this season would pro
bably lie between that of the spring and fall (five to eleven days). Then
again, the figures may be of no significance for all specimens were hatched
indoors where the fluctuation of temperature was slight compared to that
outside. The time necessary for hatching is one of the shortest of any
of the speoies for which I have been able to find data*
Under laboratory conditions
Baetis vagans 11 days (Murphy, 1911* 41)
Ameletus ludenB five months (Clemens, 1922* 78)
Beptagenia hebe 12 days (Needham, Traver, Esu, 1935 90)
Hexagenia reourvata -- 15 days (Needham, Traver, Hsu, 1935* 9C)
Ephemera varia 15 days (Needham, Traver, Hsu, 1335* 90)
Stenonema tripunctatum 11-23 days (Needham, Traver, Hsu, 1935:90)
Stenonema Interpunctatim -- 13-15 days (Needham, Traver, Hsu, 1936 *
90)
Ephemera vulgata 10-11 days (Needham, Traver, Hsu, 1935* 90)
Hexagenia bilineata 9 days (Needham, Traver, Hsu, 1935: 90)
Stenonema smithae 13 days (Original)
Caenis diminuta 5-11 days (Original)
When the nymph is ready to hatch, the chorion splits cleanly along
the longitudinal axis* The following xo from my notes of September 20,
1939 and describes the usual method of emergence of the nymphs from the
egg: "Nymph had freed head when first observed. Antennae were still
twisted, but freej also two of left legs had been released. By working




316
Tissot, adultai March 24, 1939, G* B, Merrill, adults} March 30, adults,
April 1, adults, April 5, adults, April 7, adults, all taken by J Russell
in 1940)} Lake Wauberg ( 1932-1933, R. P* Trogdon, nymphs)| 5 miles
west Gainesville (Maroh 6, 1937, L, B, nymphs)} Goat Sink about 12 miles
S, W Gainesville (April 23, 1939, F N* Y, nymphs)} Montenooha Creek
(October 28, 1939, F N* Y, nymphs)} Hatchet Creek (Maroh 22, 1937, L,
B, nymphs} Maroh 23, 1938, L B*, adults) Bay Co 3 miles west of
county line at Hwy #98 (May 30, 1940, L* B, nymphs) Citrus Co
1 l/2 miles south of Withlaooochee River (March 25, 1938, L B, nymphs)}
Floral City (April 2, 1939, F N Y, nymphs) Clay Co Green Cove
Springs (October 15, 1939, F N, Y, nymphs) Colisnbia Co 6 miles
east of Lake City (May 12, 1937, L B, nymphs)} 'll5 miles N of Lake
City (October 27, 1938, F* N Y & H H H, nymphs) Dade Co -- Miami
(April 15, 1937, F N Y, nymphs} August 20, 1937, L B, nymphs} Aug
ust 26, 1937, L B, adults} September 4, 1937, L B, adults} September
7, 1937, L B, adults)} 5 miles west of Miami (September 2, 1937, L. B*,
nymphs), Duval Co. St Johns Bluff (1853 ?, type looality of £* dimin
uta, Francis Walker, adults) Flagler Co Andalusia (April 4, 1939,
F K, Y, nymphs) Gadsden Co River Junction (June 30, 1939, L B,
adults) Glades Co, Moore Haven (May 20, 1940, L. B, nymphs) Hamil
ton Co 6 miles north of Live Oak Road at U, S Hwy, #41 (February 4,
1938, L B, nymphs), Hillsborough Co Tampa (March 21, 1937, S. Gay
lord, nymphs)} Mullis City (December 31, 1937, L J M, nymphs)} Hurrah
Creek at Pionio (Maroh 26, 1938, L B, nymphs)} Six-Mile Creek (Maroh
26, 1938, L B, nymphs)} 2 miles east of Tampa (Maroh 26, 1938, L B,
nymphs) Jaokson Co, 142 miles north of Bay Co line (June 8, 1938,


125
south of Vernon (April 2, 1938, H. H* H* and L* J* M*, nymphs); Holmes
creek (December 11, 1937, L* B*, nymphs; April 2, 1938, H* H. H* and L*
J* M,, nymphs and adults; June 9, 1938, L* B., nymphs; July 2, 1939,
L. J* M.and L. B., nymph* and adults)*
Stenonama exiguum Traver
TAXONOMYt Stenonema exiguum is another Florida species which falls into
the pulohellum-tripunotatum complex* It is rather close to S* smithae
but can easily be distinguished from this species by the characters set
forth in the key. In her description, Traver suggests that exiguum is al
so close to S* integrum* The original description included only male and
female, and at present the nymph still remains undescribed* The type
specimens were collected near Woodlawn, N. C., at the Chattahoochee river,
Atlanta, Georgia, and the Etowah river at Home, Georgia. Subsequently,
Traver has recorded exiguum from Alabama somewhere between Birmingham and
Tuscaloosa*
DISTRIBUTION! In Florida S* exiguum is known to oocur from.Hillsborough
county In the south as far north and west as the state line; eastward
the species does not go much beyond the eastern limits of Alaohua county*
Specimens from Mobile oounty, Alabama and Baker county, Georgia are also
at hand. The distribution of exiguum parallels that of S* smithae and is
almost identical with it. The close resemblance of the nymphs of the
two species makes determination of very young specimens rather difficult
and for this reason some of the individuals which I am calling exiguum
may possibly be smithae and vioe ver-a. There is a fairly large series
of adult Stenonema from Hillsborough oounty, but not a single one is


130
Choroterpes hubbelli, and the questionable one, Stenonema exiguum*
In the lake from whioh proxlmum was taken most oonmonly, there were other
animals present whioh are indicative of a stream association# Not only-
are the mayflies listed above typical stream forms, but Dr* A. F Carr
reports that the reptilian and amphibian faunae are likewise of a rheo-
colous nature* I have found sponges, caddisflies and parnid beetles, all
normal stream inhabitants living along with proximum. This condition has
been observed in only two of the sand-bottom lakes of Florida, although
it is probably much more widespread* The finding of a fauna of the lafas
shores which so closely resembles a stream fauna is similar to the con
ditions found along some of the rocky beaches of northern lakes where the
mayfly fauna is quite abundant* However, it seems apparent that only very
tolerant forms can withstand the conditions prevailing along the lake
margins in Florida. This is somewhat understandable when one considers
the slight wave action, the scant debris along the shore, the complete ab
sence of rocks or pebbles, and the small amount of vegetation.
SEASONS* Adults are known for every month of the year except September,
and this is due only to laok of collecting during this month* Nymphs were
collected in August which would certainly have emerged during September.
The speoies is known only for June (published dates) in its northern en
virons* S* int erpunctatum has been reported from the south in April and
July; pallidum was collected in May and June.
HABITS* The habits of this speoies are very much the same as those of
smithae* The nymphs are very tolerant and have been kept alive in aquaria
in the laboratory for more than two months during which time many speci
mens emerged* There is some difference, however, in the size of the adults




121
(February 4, 1938, L. B., nymphs)< Holmes Co. Sandy creek (December
11, 1937, L. B., nymphs; July 2, 1939, L. J. M. and L. B., nymphs and
adults; December 14, 1939, L. B, nymphs). Jackson Co. Blue Springs
oreek near Marianna (May 5, 1933, adults; December 11, 1937, L. B.,
nymphs; June 6, 1940, H. H, H. and L. B., adults); 3.6 miles north of
Altha (December 10, 1937, L. B., nymphs; June 9, 1938, L. B., nymphs and
adults; December 1, 1939, L. B., nymphs and adults). Jefferson Co.
(April 1, 1938, H. H. H. and L. J. M., nymphs). Leon Co. 15.6 miles
west of Tallahassee (June 5, 1938, H. H. H., F. N. Y., L. B., nymphs;
March 17, 1939, L. B., nymphs; November 30, 1939, H. H. H. and L. B.,
nymphs); 11.2 miles west of Tallahassee (March 16, 1939, L. B., adults
and nymphs); 1 mile south of Hwy# 19 on #127 (June 5, 1938, H. H. H., F.
N. Y., L. B., nymphs and adults); 7 miles south of Hwy. #19 on #127 (June
5, 1938, H. H* H, F..N. Y., L. B., nymphs). L3vy Co. Gulf Hammock
(Deoember 21, 1938, W. M. MoLane, nymphs). Liberty Co. Sweetwater creek
(May 7, 1933, J. D. Kilby, nymphs; June 10, 1938, H. II. H., F, N. Y., L. B.,
nymphs; November 4, 1938, L. b., nymphs; July 1, 1939, L. J. M. and L. B.,
nymphs; December 1, 1939, H* H. H. and L. B., nymphs and adults); Kelley
Branch (December 10, 1937, L. B., nymphs); Little Sweetwater oreek (December
10, 1937, L. B,, nymphs; June 10, 1938, H H. H., F. N. Y., L. B., nymphs);
Hosford (November 30, 1939, H. H. H. and L. B., nymphs); 10 miles south
of River Junction (March 17, 1939, L. B., nymphs); 4.5 miles north of
turnoff to Torreya State Park (June 10, 1938, H. H. H., F. N. Y., L. B.,
nymphs). Madison Co. .8 miles east of Jefferson county line (February
5, 1938, L. B., nymphs); 4.3 miles east of Jefferson couty line (February
5, 1938, L. B., nymphs); 3 miles west of Greenville (February 5, 1938,


274
oratory it even occurred after dark. Life as a subimago extends from late
in the afternoon of the emergence date xntil late afternoon of the following
day, the number of hours varying from twenty-two to twenty-five for both
sexes
The mating flight of E. trilineata has not been observed,and descrip
tions of the phenomonen in other species of the genus Ephemeralla are al
most non-existant* A search of the available literature revealed not a
single description of this important event*
DCRIILATIOH OF THE SPECIESs Ephemerejla trilineata may be endemic to the
region from which 1 have records* All close relatives are more northern
in distribution, and there is little reason to doubt^that E* trilineata
arose outside of Florida and entered through the drainage of the Apalaohi-
cola river* E* temporalis and doris have both been taken in Georgia, but
only the latter from the Coastal Plain in North Carolina# 3y far the great
est part of the subgenus bicolor is known from the Appalachians and south
eastern Canada*
An alternative possibility with respect to mode of origin is suggested
by a consideration of the effects of the Pleistocene glaciation. If we
assume that the bicolor group (or its ancestors) was driven south by the
advancing ice sheet, the relatively few ancestral species of the subgenus
may have become conoentrated in the southern Appalachians and the Piedmont*
With the retreat of the glaciers, the very flexible group moved northwards
and began an expansion until the great amount of speciation of today was
realized; at the same time, some forms remained in the Piedmont and the
Coastal Plain# Trilineata arose from the relict stock and thence spread
into Florida and southern Alabama*


The wide limits of toleration of smithae nymphs adapt them to many
and varied conditions, alio .ring them to become the most frequently en
countered mayfly nymphs in the streams of Florida. The nymphs are not at
all, or very little, affected by pH, for I have found them inhabiting a
svrsmpy, slowly flowing body of murky water with a pTT somewhat below 4.0
(the meter would read no lower)) however, nymphs of the same species
were found to be quite at home in a clear, sar,d-bottcm spring run which has
a pH of 7.8. Sven though this is not as wide a range as that occupied by
Callibaetis floridanus, It is certainly far beyond that of most mayfly
species. Temperature likewise does not seem of greet import because nymphs
inhabit water with a temperature of thirty degrees centigrade, and the same
species may be found in enter which at times has ice formed in its quieter
portions. Because of the wide ecological valence cf smithae, it does not
appear logical that the species should stop its southward range at Alachua
county, but such seems to bo the case. One can readily see that stream
mayflies could not proceed .cell in the canals of south Florida, but the
clean, sand-bottom creeks of Hillsborough county are not essentially
different from those of north-central Florida. It may be that when this
part of Florida is more thoroughly studied, the species will appear in
collections, but until such is done, it must be assumed that smithae is
absent from this area.
The small pebbly riffles in the sand-bottom creeks of north-oentral
Florida, and to some extent in northere stern Florida, also afford an ex
cellent collecting place for nymphs of smithae. The nymphs tend to con
gregate in such places, for, from the standpoint of food, the conditions
are excellent, the current is as swift as can be found in the stream, and


227
crevices as well as or the protected sides of these objects. As a rule,
they shun the oenter of the stream and live where there is little movement
of the water. In only one case, were nymphs taken from the middle of the
stream, and in this, the Fenhollcway river, the flow was almost negligible.
Another locality, the Styx river, presented a picture of stagnation with
typical vegetation of this type of habitat, yet bradleyi tos found here
in association with ether mayflies some of which are typical inhabitants
of standing bodies of water. These two streams drain flatwoods and swamps
which give the water a brownish tinge and also produce a definitely acid
condition, 5.6 and 5.8.
The ephemerids which are associated with P* bradleyi are Callibaetis
floridanus, Caenis diminuta, otenonema smithae, habrophlebiodes brunneipennls ,
Sphemere11a trilineata, Siphlopleoton speciosum, and Blasturus intermedius.
SEASONS* Records indicate that emergence occurs throughout the winter,
beyond this period, nothing is known. Nymphs in their last instar have
been collected in November, December and February while adults were taken
in February. Nymphs one-third grown were collected in October and those
taken in November were half grown; the February specimens were in either
their last instar or penultimate instar. The type specimens taken by-
Bradley wore captured on December 21, 27, 28, and 29. The single adult
from Hatchet creek collected in February was first seen as it was being
delicately manipulated in the jaws of a spider, but the mayfly was soon
taken away from him to beoome a valuable addition to my collection. After
discovering this to be bradleyi, I searched the stream diligently for nymphs
and have continued to this for more than two years, but as yet my efforst
have met with no success


244
CHOROTERPES Eaton
In the nymphal stage, Choroterpes is quite distinctive by virtue
of the morphology of the gills; the adults are easily separated from
other mayflies by the struoture of the male genitalia and the venation
of the metathoracic wings, Eaton erected this genus in 1881 to include
the one species whioh he knew (he also had an undescribed species from
Arizona before him), £ piotetl of Europe,
E\ren though the genus is so easily distinguished, the species within
the genus are much more difficult to separate. There are eight described
species and one new one from Florida known at present. For the most part
the species are separated by color pattern and by the shape of the basal
segment of the forceps of the males,
Choroterpes is a Neotropical, Holarotio, and Indo-australian genus.
In the Kearctio it is widely distributed; published records are from
Alberta to California, from Ontario to Texas, The Florida species is
the first record of the occurrence of the genus in the southeast,
Leptophlebia, Blasturus, Thraulus, and Choroterpes form a closely
knit group, but Spieth has concluded in his phylogenetic study that
I.eptophlebia and Blasturus present a closer affinity to each other than
they do to Thraulus and Choroterpes,
Choroterpes hubbelli ms, name
TAXONOMY: Choroterpes hubbelli can be distinguished from all other species
in the genus by its dark abdomen and pale, unbanded caudal filaments.
It is Gui unexpected species which turns up in unexpected places. While


275
Opposed to this hypothesis is the fact that, in general, the mayflies
are an old and conservative group and do not show evidence of rapid modern
speciation. However, this is not necessarily true of all groups, and if
any genus of mayflies is new undergoing prolific speciation, it is certainly
Ephemerelia
LOCALITY RECORDSt Alachua Co. Santa Fe Lake (April 2, 1955, A M. Laes-
sle, nymphs; April 7, 1957, L* B,f nymphs end adults); 1 mile west of
Newman's Lake (May 11, 1S37, L E, nymphs; January7- 8, 1938; January 25,
1038, L. B, nymphs); 3 miles north cf Paradise (February 12, 1938, G. Van
Hyning, nymphs); near Y/orthington Springs (February 5, 1939, A. C. Chable
and W. M. Beck, nymphs); Hatchet Creek (March 22, 1937, L* B,, nymphs;
February7- 8, 1938, L. B, nymphs; February 26, 1938, L. B, adults; March
23, 1938, L* B., adults; April 2, 1938, L. B, adults; April 18, 1938,
L. B, adults; May 5, 1930, L B*, adults; November 13, 1938, L. B, nymphs;
March 5, 1939, M Carr, nymphs, imagos reared ilaroh 16 and 26; March 22,
1939, L. B, imagos; April 1, 1939, L# B*, nymphs and adults, imagos rear
ed April 2, 4-6, 8, 10, 13, 14; April 5, 1939, L. B., adults; April 13,
1939, L. B, nymphs and adults, imagos reared April 14, 17, 20, 21; May
6, 1939, L* B., adults; June 24, 1939, L. B. adults; February 16, 1940,
L. B,, adult3 and nymphs); Santa Fe Lake (January 30, 1940, L. B., nymphs,
imagos reared February 7, 8, 14); 2 l/2 miles west of Gainesville (Feb
ruary7- 5, 1940, L. B, nymphs, imagos reared March 1, 9). Columbia Co,
Fulling Creek (November 13, 1938, L. B,, nymphs). Gadsden Co* River
Junction (March 17, 1939, J. S. R., E. H, H., F. N. Y., L. B., nymphs);
4 l/2 miles south cf River Junction (March: 17, 1939, J S. R., H. H. E.,
F. N. Y,, L. B., nymphs). Hamilton Co. .6 mileB north of Live Cak road


/> &
TABLE OF CONTENTS
C)
The mayflies of Florida
Historical review
The problem
The order Ephemeroptera
Primitive and specialized characters
The families of mayflies
The wing venation of mayflies
Taxonomic characters
A comparison of Florida mayflies with the northern fauna 33
Taxonomy 33
Comparative abundance 35
Comparative eoology 36
Comparison of life histories 38
Zoogeography 41
Dispersal of mayflies 45
Climatio divisions of Florida 49
The habitats of Florida mayflies 51
Descriptions of habitats ..# 52
Streams 52
Intermittent creeks 52
Permanent creeks .. 53
Sard-bottom creeks with little vegetation 53
Sand-bottom creeks choked with vegetation .* 54
Silt-bottcm creeks with little vegetation . 55
Silt-bottom creeks choked with vegetation * 56
129675
3
7
9
13
22
25
27


396
27, 1937, L J M, nymphs; March 26, 1938, L. B, nymphs); Mullis City
(December 31, 1937, L J M, nymphs); Little Fish-hawk creek (Maroh 26,
1938, L. B., nymphs); 2 miles west of Alafia (March 26, 1938, L* B,, nymphs)
Holmes Co* Sandy creek (December 14, 1939, L B, nymphs) Jackson Co*
36 miles north of Altha (December 10, 1937, L B, nymphs; June 9,
1938, II. H H, *. N. Y, L* B,, nymphs; July 1, 1939, L. J. M., L. B,
nymphs and adults); Florida Caverns State Park (December 2, 1939, L B,
nymphs) Jefferson Co Drifton (February 6, 1938, L. B, nymphs)
Leon Co 7 miles south of Hwy #19 on #127 (June 5, 1938, H H H, F,
N, Y, L. B, nymphs) Liberty Co Sweetwater creek (November 4, 1938,
L. B, nymphs; July 1, 1939, L, J M, L 3, nymphs; December 1, 1939,
L B., nymphs). Madison Co Auoilla river (June 4, 1938, L B, nymphs
and adults) Marion Co -- Eureka, Oklawaha river (February 12, 1938, L. B.,
nymphs); Rainbow Springs (March 9, 1940, L B, nymphs). Okaloosa Co
51 miles west of county line (June 7, 1938, H. H. K, F. N. Y, L. B,
nymphs; May 31, 1940, H R h, and L. B., nymphs); Crestview (December
11, 1937, L. B., nymphs) Santa Rosa Co* Pace (June 1, 1940, H H H
and L B, adults) Wakulla Co -- Smith Creek (June 5, 1938, L. B., nymphs);
Viakulla Springs run (May 29, 1940, L. B, nymphs). Walton Co 73 miles
west of Ebro (June 7, 1938, L B., nymphs); 10,6 miles west of Washington
county line (May 31, 1940, L B, nymphs); 26 miles west of Freeport
(June 7, 1938, L. B, nymphs); 13.8 miles west of Freeport (June 7, 1938,
L B, nymphs); 9.6 miles west of Portland (May 31, 1940, L B, nymphs)#
Washington Co* Holmes Creek (December 11, 1937, L. B., nymphs; July 2,
1939, L. J M. and L B, nymphs)*


Map 5* Distribution of
Stononama sn.it hae.


250
final molt, but this has been almost an impossibility in the laboratory
under normal room conditions. One male and one female imago were obtained
by placing subimagos in paper sacks with wet blotters in the bottom. Two
other successes were registered by using the bell-jar method discussed under
Blasturus intemedius. Subimagal life lasts eight to ten hours and in some
cases may be even shorter. The female in this species, as in most other
mayfly species, molts with much greater ease than does the male.
Mating flights have never been observed for C. hubbelli. A search
of the literature reveals that the only published observations of this
phencanonen in other species are those of Needham (1905 38-59) and Morgan
(1913: 392). The former author described the flight of C. basalis as
follows: "Not many imago s were observed at large except on early afternoons,
when the sunshine was warm and bright. Then they wrould swarm out in the
opening of the gorge, and dance high up in the air between the banks of
green in myriadB. Rising and falling in rapid undulations, moving in large
companies up and down the gorge, they rarely descended low enough to bring
the lowermost within the reach of the net} and when by climbing on a big
rock in the opening I captured a netfull of them I found they were all
males." Morgan described the mating flight of the seme species: "On
June 25th a swarm of three or four hundred individuals of Choroterpes
basails were swarming over the water of Fall Creek at about four o'clock
on a sunny afternoon. Their average fise must have been thirty feet. From
the swam both males and females were captured, but mating was not observed."
DERIVATION OF THE SPECIES It appears probable that C. hubbelli is derived
from some northern stock, and h&3 become isolated in the southeast; origin
was likely close to the Coastal Plain and occupation of the province vras


226
and prominent main traoheae provided with numerous lateral branches
As far as I can tell from existing descriptions, no other species of
this genus has gills composed of two separate plates* In Blasturus, the
gill lamellae are produced into one or two blunt lobes at the base of the
terminal filamentj in bradleyi, on the other hand, the gill lamellae are
rounded*
P* bradleyi is more primitive than Blasturus, but more advance than
Paraleptophlebia proper as shown by the following considerations* The first
gill of bradleyi differs from the other six gills just as does the first
gill of Blasturus* This gill is bifurcate, each branch having a single
traohea whioh laoks lateral branchesj these tracheae split off from the
main trunk before the bifurcation occurs* The lack of posterior angles
on the gill8 seems to indicate a less highly developed type of gill than
that of Blasturus* Bpieth (1933t 85) stated "the modifications that the
gills have undergone inolude the flattening of the gill into a foliaceous
organ and the changing of the gill from a simple, finger-like out-pocketing
into a double organ oonsisting of two leaves lying against each other"
In all Paraleptophlebias except bradleyi, the seven pairs of gills are
similar and without posterior angles* Another major difference between
P. bradleyi and the remaining speoies assigned to this genus lies in the
structure of gills on segments two through seven* In Paraleptophlebia s. s*
the gills are divided only part way to the base, and overlap, if at all,
only to a small extent basallyj in bradleyi and Blasturus, on the other
hand, the gills are divided to the base and overlap extensively* In all
other characters, the nymphs of P. bradleyi, the other species of Paralepto
phlebia, and Blasturus are quite similar*


157
LOCALITY RECORDS* Calhoun Co* Chipla river (November 5, 1938, L* B*,
nymphs)* Gadsden Co* 15*1 miles east of Chattahoochee (April 1, 1938,
H* H* H* and L* J* M*, nymphs); 4 l/2 miles south of River Junction
(March 17, 1939, J* 3* R., H* H* H*, F* N* Y, L* B*, nymphs; June 30,
1939, L J* M* and L. B*, adults); 10 miles south of River Junction (July
1, 1939, L* J* M* and L* B*, nymphs)* Holmes Co* Sandy Creek (July 2,
1939, L* J* M* and L. B., nymphs)* Jackson Co. 3*6 miles north of
Altha (July 1, 1939, L J* M* and L* B*, nymphs)* Liberty Co* Hos-
ford (March 17, 1939, J* S* R, H* H* H,, F* N* Y*, L* B, nymphs; Nov-
ember 30, 1939, H* H* H*, W, M* McLane, L* B, nymphs); Sweetwater Creek
(May 7, 1933, J. D* Kilby, adult; June 10, 1938, L* 3., nymphs; November
4, 1938, L* B*, nymphs; December 1, 1939, H* H* li* and L* B., nymphs).
Okaloosa Co* < near Shoal river (December 12, 1937, L. B*, nymphs); 1
mile east of Crestview (December 12, 1937, L* B*, nymphs)* Walton Co* --
2 miles west of Freeport (April 3, 1938, Hobbs and Marchand, nymphs);
16*8 miles west of Ebro (June 7, 1938, L* B., adults); 2*1 miles west
of Walton county line (May 31, 1940, H. H. B* and L* B, nymphs and adults)*
Washington Co* Ebro (May 30, 1940, H* H* H* and L. B*, adults); Koines
Creek (April 2, 1938, H* K* H* and L* J* M*, nyiaphu and adults; June 9,
1938, H* H* H*, F* N* Y., L. B, adults; July 2, 1939, L* J* M. and L* B*,
nymphs and adults, some nymphs reared on the following dates July 5, July 7,
July 16, July 18, July 31, August 7, August 10, August 27, September 11)*
Bexagenia orlando Traver
TAXONOMY* In her paper on the species of Hexagenia occurring in the south,
Traver (1931) described two new Florida species, H* orlando and H. weewa.




187
it is found all the way to the state boundary and collections from southern
Alabama, i. e, Baldwin and Mobile counties, include a few nymphs of this
genus. Isonyohia is very poorly known from the Coastal Plain, the Florida
species and. the Mississippi species (i. rufa) being the only ones recorded
from the province.
much work nas been done on mayflies in the southeastern part of
Canada, yet Is onychia has not been found to be a predominant element of
the stream fauna as is true for the species of the mountainous sections
of the southeastern united States.
I collected mayfly nymphs in a stream in the northern part of the
Coastal Plain m Alabama during June, and found that, by far, Isonyohia
nymphs were the most conspicuous element, faunistioally, in the stream.
The opposite oecomes true as one travels southward, and in the Florida
streams Isonyohia is much less common than are the various B&etiue species.
The familial placement of Isonyohia is debatable. Spieth (1933s329)
considers that all of the affinities of tais genus lie with the heptageni-
idae the shape and number of the segments of the genital forceps, the
structure of the maxillae,and the structure of the gills. Traver (1935)
takes another view and places Isonyohia in the Baetidae, allying it with
the Ciphlonurinae, but she gives no evidence in support of her opinion.
In this paper, tae genus will be considered as one of the Baetidae,
although characters are simred in common with both the Baetidae and Hep
tageniidae. It is doubtful that Isonyohia is an intermediate between
these two families, but probably represents an offshoot somewhere near
the base of the stook. The shape of the genitalia, the forceps base, the
shape of the mandible and of the labium "all indicate modifications that


141
you have a variety of orlando or a new species." Subsequently, adults
were oollected which seem to be orlando, and they appear almost identi
cal with a specimen of orlando, from Albany, Georgia, sent to me by Dr,
Traver* Because the specimens which I am now calling H. limnophila(ms,
name)differ eoologioally as well as in maoulation from the true orlando,
I believe that the two should certainly be separated, but whether or not
limnophlla should be regarded as a subspecies of orlando must be determined
by further study of a much larger series of the latter than is now avail
able.2
Structurally, the species is not very different from the limbata
oomplex, and, in fact, specimens from Lake Harney, Florida were before
Eaton when he studied limbata (whioh he called H. variabilis ).** I have
been unable to find any reference to the identity of the other specimens
used in his description, but since his adults came from "tibah Lakej Texas!
Florida; St. Louis, Mo.; Galena and Rook Island, Ill.; Detroit, Mioh.;
New England; Philadelphia; and Vfashington, D. C." it certainly does
not seem logical that they should all be the same when there is suoh a
great amount of speoiation in the genus.
DISTRIBUTION! H. limnophlla is endemic to the Central Highlands of Florida,
and is entirely a lake species. Lake Harney, from whioh Eaton's specimens
of "variabilis" came, is on the edge of the lake region, and is an en-
2. Spieth considers orlando to be a subspecies of limbata (verbal communi
cation).
3. Ulmer (1921i 233-239) has cleared up the taxonomic confusion concern
ing H. limbata. His study of type material proved that H. variabilis
Eaton is identical with K. limbata(Guerin), and therefore the former
has no valid standing.


10
monta are somewhat hairy ant relatively short in the s ubi.nag but usually
lose this iiairy condition and become elongated in the imago; and in the
males which have divided compound eyes, t.iese are loss prominent and rat
her dull in the sub imago and very prominent and glossy in the imago*
The eggs of nearly all mayflies are laid in fresh water, where a vary
ing period is required for development to take place. The freshly hatched
nymphs possess no gills, out with_n one to three molts these structures
make their appearance; the mouthparts, ho.vever, are all present, though
generalized and simple in form, boon the nymphs assume the body shape
and structure which they retain over moat of their nymphal life. In the
few species, the life history of which has been completely worked out,
there are at least tv/enty-five preadult molts,and in most cases more than
tais number are thougl/to occur, some species requiring as many as forty-
five*
The nymphs of mayflies are adapted to their environments in many and
various ways, though they all share certain features in common, such as
gills, caudal filaments, and chewing mouthparts. (A species recently de
scribed by bpieth lacks the molar area on the mandibles). The burrowing
species exhibit some of the moot remarkable adaptive characteristics; in
these nymphs the legs have became flattened, digging structures the
fore legs are used for pushing the silt aside, the hind legs for passing it
back out of the burrow* The frontal process of the head and the greatly
elongated tusks, or rami, of the mandibles first encounter the silt in the
digging process, loosening it so that tue legs may complete the task of
excavation and removing tne material. The gills of theoe burrowers are
feathery and thoroughly penetrated by tracheae, so that there is a par-


32
the other; for nature preserves or eliminates species as wholes."
Mouthparts and head shape are the familial characters used to separ
ate the families of mayflies in the nymphal stages. The subfamilies,on
the other hand, are to a large extent separated by the structure of the
mouthparts and the structure of the gills, of which the latter are probably
the more important.
3ill shape and structure are extremely varied. They may be foliaceous,
six-gle or recurved; they may be highly traeheate or completely lack these
air tubes; they may be present on seven abdominal segments or they may
be absent from some of them; they may lie flat on the abdomen or they may
be so shifted that they serve as suckers on the venter of the insect;
they may be modified so that some fom protective covers for others or
they may be completely exposed; they may be strongly muscled so that they
can be vibrated very rapidly or they may be so flabby that such reactions
are out of the question; they may be entirely confined to the abdomen
or, in a few oases, gills may also ooour on the thorax or even on the
maxillae. In short, the gills are probably the most variable structures
to be found in the nymphal Ephemeroptera.
Since hind wings are absent in the adults of some species of mayflies,
naturally their iramaturee lack hind wing pads* The presence or absence of
these metathoraoio wing pads is used as a taxonomic character whenever
possible.
The caudal filaments, two cerci and one median tail, are very use
ful in studies of the nymphal forms. In some species, these are vexy
flexible organs, while in others they are sturdy swimming structures. The
cerci of many of the genera are densely clothed with hairs medially and


1G3
CAMPSURUS Eaton
Camp sums is a rather unique mayfly in that the legs (except the
fore legs of the males) have become weakened and aborted so that they
are no longer of any use to the adult insect as ambulatory organs.
This and other distinctive features make Campsurus taxonomically quite
distinct from all other genera of North American ephemerids.
In South America, Campsurus is one of the predominant mayfly genera.
Needham and Murphy (1924j 13) state that the genus includes nearly a
fifth of the described species of the entire neotropical region. In
North America, on the other hand, only four species of Campsurus are
known, all limited in their distribution to the Coastal Plain. £ primus
was described from Grand Tower, Illinois at the edge of this province;
C* deooloratus was described from Matamoros, Mexico just across the bor
der from Brownsville, Texas, and its range extends northward to College
Station, Texas, which is very dose to the Fall Line; C. puella is known
only from New Orleans; and C. incertus occurs in southern Alabama, south
ern Georgia, and North Florida.
Spieth (19331 347-348) considers that, because of the stuap-legged
condition, the genus stands distinct from the other burrowing mayflies
of North America and represents a separate phylogenetic branoh. His
arguments are clear, and seem in all respects conclusive.
The mating flight of Campsurus segnis in British Guiana has been
picturesquely described by Dr. Ann Morgan (1929* 62^63). The anatomy
and taxonomy of this species were also treated by her and also by Need
ham and Murphy (1924* 19-20).


BAETI5CA Walsh
Iloe genus Baetisca is not a particularly large one, being composed
of but eight species three of which wore described since 1934* These
insects are so distinctive that Ulmer (1933: 209) placed them, in a sep
arate family (Baetiscidae), Bpieiu (1953 367) in a separate superfamily
(baotisooidea), and Traver (1933: 535) in a separate subfamily (Baetiscinae)
Baetisca nymphs are the moot unusual looking mayfly nymphs in 'North
America. With their stout, spinous, humped-up bodies, they might yjoII
rival some of the most bizarre types of dinosaurs of the Mesozoic. The
following is talen from Walsh (1364 200-201) "I had sent a female speci
men [Baetisca obesa] of the above pupa to Br hagen in 1363, and subjoin
his remarks on it, translating from tne original French MS* 'The larva
No* 6S is the most extraordinary animal that x have seen, so that I asked
myself whether it really belonged to Insecta. But there is no doubt of
the fact of its being the larva of a hexapod insect. The large compound
eyes determine at once its position as belonging to those insects which
have an incomplete metamorphosis, and therefore to Orthoptera, or Hemiptera.
'..* On the whole, it is about the most extraordinary larva known
to science.' "
in general, the adults of the genus are not as readily identified
as are the nymphs. Needham (1935 235) makes a sage statement but one
which, carnot be taken too literally when ne says "In such genera [Baetisca
and Upbornereilaj differential characters are often better developed in
the nymphs than in the adult. In genera we believe that species are best
described in the state that is most differentiated, aad therefore, most


334
Although in south Florida no mayflies have been found which show
the characters of the north Florida Callibaetis, in the Gainesville area
I have taken insects which are very similar to the south Florida forms
From an examination of the specimens at hand it seems that two subspecies
of C. floridanus inhabit Florida with their region of intergradation probably
in central Florida. Since I have only nymphs from the region between
Highlands and Marion counties, the separation must be tentative; when adults
are secured from the intervening area, C, floridanus floridanus and C.
floridanus minor may prove to be distinct species The appearance of
C. f. floridanus in the Gainesville area may be only a further indication
of the racial character of the two populations; the region of intergrada-
tion may be in this more northern locale rather than in central Florida,
and the true C. f. minor may occur further north and west.
In the taxonomy of the genus Callibaetis, the males and nymphs are
much more difficult to identify than are the females In the Florida species,
the nale3 and nymphs are not exceptional and without females identification
must be tentative#
DISTRIBUTION: C. £, floridanus is distributed throughout the southern tip
of Florida and is known to spread as far north as Highlands county. Pro
bably with further collecting in oentral Florida, the species will be found
to have a much wider range. C. f. floridanus occurs throughout the Ever
glades, but is not found on the Florida Keys (I have seen no fre3h water
in which the nymphs might live, and there appears to be no brackish water
there which might be suitable for them).
C, f. minor occupies a range extending from Lake county north into
Georgia and northwest to Jackson county. The species most likely spreads


313
the young nymph lashes out with its csaudal filaments, then bends them
completely back, over the abdomen and lashes out again, producing a series
of jerky, somewhat undulatory, motions* During this process, the legs are
held widely spread and ready to grasp any support* Until the operoulate
gills are formed, the nymphs retain their whitish, opaque appearanoej
shortly after the formation of these giilB brown pigment begins to color
the immatures, and they are further concealed by the detritus which
adheres to the long hairs covering the body*
For same time I entertained the idea that this speoies was partheno-
geretio, but numerous attempts to hatch eggs fresa last stage female nymphs,
from subimagos, and from virgin imagos resulted only in disappointment*
For controls in these experiments I used females which were taken at the
campus light mentioned above* These had almost certainly mated, and their
eggs invariably hatohed*
Emergence of C# diminuta adults occurs late in the afternoon or at
night* The nymphs, when ready to emerge, float free at the surface in
shallow water from three to four feet deep just inside the limits of
attached vegetation* The subimago soons bursts free frem the nymphal skin,
but a great deal of difficulty seems to be experience in taking flight*
In many oases, the subimago is unable to rise from the water at all, and
during its struggles the wings become wet spelling the doom of the insect*
Frequently, the subimago will take off from the nymphal exuvium, but the
flight results in only a short hop and another attempt is made after the
insect has rested briefly on the surface film* Once free and safely in the
air, the subimago flies to the nearest support and very shortly molts* In
the instance of specimens reared in the laboratory, the molt occurred ap-


358
magos#
A# propinquus is very similar to A# ephipplatus and can be differentiated
from the latter only by the fact that ephippiatus has some dorsal markings
on the pale abdominal segments# I have found several speoimens of ephippla-
tus on which these markings are obsolescent, and b -cause of this and the
very similar venation and genitalia, the insects Which I am calling pro
pinquus may be only variants of ephipplatUB#
DISTRIBUTION! Aoerrfcrella propinquus has been recorded from three localities
in North America! Rock Island, Illinois (type locality)j Sheffield, Alabamaj
and Marianna, Florida# Each of these localities is in a different physio
graphic province, and the character of the streams must certainly be very
different, but, as mentioned elsewhere in this paper, many northern forms
find ingress into Florida by means of the Apalaohioola river drainage system.
In Florida, the species is now known from places as widely separated as
Blue Springs creek near Marianna and frcm the Hillsborough river near Tampa#
(Sec rr*.p ¡ 8).
ECOLOCrYt The adults which were all taken at streams that are definitely
basic are the only representative of propinquus in my collection* Beoause
of the scarcity of the species in Florida, I believe that the nymphs must
be confined to water in which the pH ranges aboye 7#0* The imagos from
Blue Springs creek were taken at a lighting sheet, the adults from the
Hillsborough river were found clinging to the wall of an old dam in oompany
with numerous subimagos of several other Baetinae and Stenonema#
SEASONS! This species probably does not differ in its period of emergence
from the other Baetinae, i# e# it is year round. Adults are known only
for July 1 and October 21, no other information concerning the Florida
insect is available


Needham, J* S* 1932. Three new American mayflies. Oan&d. Ent. 64: 273-
276, 1 text fig.
Needham, J. 6. and Christenson, R* 0* 1927. Economic insects in some streams
of northern Utah. Utah Agri. Exp. Sta. Bull. No. 201
Needham, J. G. and Murphy, E. E. 1924. Neotropical mayflies. Lloyd Library
Bulletin No* 24, Ent. Ser. No. 4.
Needham, J. G*,Traver, J. R., and IIsu, Yin-Chi. 1935. The biology of
mayflies with a systematic account of North American species* Comstock
Publishing Co., Ithaoa.
Rogers, J. S* 1933. The ecological distribution of the crane-flies of
northern Florida. Scol. Monographs. 3: 1-74, 25 figs.
Schock, G. 1387. Bphemerelia gnita, Poda, eine Paedogentisohe Ein-
tagsfleige. M. T* Schw. Snt. des. Vli, pp* 48-50.
Smith, 0. R. 1933. The eggs and oviposltion of mayflies. Abstract of
thesis presented to graduate school, Cornell Univ* (Enlarged in
The Biology of Mayflies).
Snodgrass, R* E.1935. Principles of insect morphology. McGraw-Hill Book
Co*, Inc. New York.
Spieth, E. T. 1933. The phylogeny of some mayfly genera. Jour. N. Y*
Ent. Soc. 41: 55-86, 327-390, plates 16-29.
1936. The life history of Ephemera simulans in Lake .Yarnsee.
Caad. Ent. 68: 263-266, 1 plate.
1937. An oligoneurid from North America. Jour. N* Y. Ent.
See. 45: 139-146, 1 plate.
...... 1938a. A method of rearing KexagerAa nymphs. Ent. News
49: 2932*
Two interesting mayfly nymphs with a description of a new
species. Amer. Mus. Nov* No* 970, pp. 1-7, 2 plates.
....... 1938c* Studies on the biology of the Ephemeroptera. I.
Coloration and its relation to seasonal emergence. Caad. Ent*
70: 210-218.
...... 1938d. Taxonomic studies on Ephemerida. 1. Description of
new North American species. Amer. Hus. Nov. No. 1002, pp. 1-11,
1 text fig., 1 plate.
...... 1940a* The North American Ephetmeropteran species of Francis
Walker. Ann. Ent* Soc. Am. 33: 324-338*


425
nymphs are placed in still water and stimulated, they move rapidly but
very awkwardly. The tails have undergone such extensive changes that they
are no long the efficient propelling organs of Baetis or Callibaetis, but
merely trail out behind the insect and act as sensory structures. If a
resting nymph be inoited to move, he may crawl a short distance, then come
to rest agRin. If the impulse is stronger, the nymph may attempt to
swim away from the source of annoyance. This act is accomplished by vigor
ous abdominal undulating and strong lashing of the almost useless caudal
filaments. The ivhole process is very awkward, and the insect does not
move far; as soon as swimming has ceased, the insect usually spreads its
legs, separates and raises its tails, arches its back, and settles slowly
to the bottom of the pan or dish.
Pseudocloeon nymphs have become highly specialized for life in running
water. Dodds and Hi saw (19241 142-143) pointed out that all such structural
modifications as those exhibited by Pseudocloeon nymphs adapt them to the
swiftest waters. In their discussion of Baetis bioaadatus (this will
certainly also apply to P. alachua, for it has undergone the same changes
as B. bioaudatus) these authors stated that n the important changes [adapta
tions for inhabiting Ter/ swift streams and torrents] are a great increase
in the relative size of thorax and legs, with a corresponding reduction
of the abdomen, including an almost entire disappearance of the hairs of the
caudal cerei. The decrease in absolute size of the body is probably also
of signifioanoe, inasmuch as a small body offers less resistance to the
current, than a large one. Within the genus Baetis, as illustrated by our
three species, the progressive adaptation to swift water follows the same
line as that which differentiates this type from the swimming type, namely


421
of coloration, in the gills*
DISTRIBUTIONS The distribution of P. alachua is rather interesting, for
the species is confined to that part of the state extending straight north
from Hillsborough county into Madison and Hamilton counties. Although
areas to the west of these counties have been thoroughly collected, only
parvnlum nymphs were t a Iran.
It is quite likely that P# alachua is one of the few endemic species
of mayflies in Florida,although until further collecting of Georgia streams
is carried out, this must remain conjectural* P* parr ulna, the most closely
related species, is known only from Ontario and Alberta and questionably
from Florida. (Jec ^ ^
ECOLOGY Ecologically, P. alachua nymphs are confined to streams of the
sand-bottom type, or to clear, moderately flowing streams such as Rain
bow Springs run. Nymphs have been taken from a creek of the former type
that was not over a foot wide and three to four inches deep (at low water),
as well as from Hatchet creek, which lias been previously been described.
The situations most preferred in these streams appear to bo the upper 3ides
of rocks or other solid structures in the BWiftest current* Here, the
nymphs cling with their heads facing the current and with barely perceptible
movements carry on their feeding activities* Figure V shows the positions
taken by the nymphs on the surface of a rock in midstream; the rock ms
partially embedded in sand,and was covered with about one inch of water*
On this stone, the Pseudocloeon nymphs were mostly on the upper surface in
very exposed placed, seldom taking to the crevioes, but Baetis spinosus
nymphs tended to remain in more sheltered areas, especially on the down
stream side of the rock# The number of nymphs on this one roek (about 12 x


234
nymph when it is plaoed in any sort of current.
The orientation of hexagenia variabilis adults to air ourrents was
discussed by Kreokar in 1915. H. brunneipennls exhibits this reaction
admirably. By blowing gently on the adult, the insect can be made to turn
in almost any direction, and it is only when the force of the air current
becomes excessive that the adults are forced to fly. In fact, the stronger
the current, the more firly the imago attaches itself. As Krecfcar mentioned
(1915384), orientation is normally with the head turned toward the air
c'orrent. From his experiments, he stated that "There is,therefore, evidence,
i believe, for concluding that Sphemeridae do not orient positively to a
breeze because of sensations derived from the breeze per se but that they
react positively to tension exerted on the muscles of attachment*"
LIFE HISTORY Development of nymphs from egg to adult probably takes six
to eight months but this developmental period is not definitely known* In
spite of numerous attempts to hatch eggs, all have failed* I have repeatedly
tried to bring about artificial fertilization and have attempted to induce
part henogenetio development, but without success* In addition, females
which I believed to have been impregnated were "stripped" of their eggs,
which were placed in small dishes some of which were unaerated, others well
aerated* At the endo of three weeks no development could be discerned in
any of the eggs. Clemens (1915) found that the eggs of Arnelet us ludens,
a parthenogenetic mayfly, took five months to incubate. He correlated this
long incubation period with the faot that the nymphs of this species live in
intermittent brooks and he explained this relationship by the assumption that
drying is necessary for development. This is certainly not the case with
H. brunneipennls for the streams which it ooouples are permanent. The eggs


200
channel can be detected which is entirely free of the -vegetation mats
and the bottom here is sandy This part of the stream is small, not more
than a few feet in width, and on the bed are many logs, sticks, and other
cebris. Collections have been made at Holmes creek subsequently but no
other Isonychia sp* B nymphs or adults were taken#
Holmes creek is a typical acid, swamp stream of the sort found in
northwest Florida, and the description of this type of creek in the sec
tion dealing with aquatic habits includes a fuller discussion of this
waterway*
Several other species of mayflies have been collected from the vege
tation and. submerged logs in olmes creek. These include baetis spinosus,
_B. spiethi, Cloeon rbropiotun, C. ayssa, Paraleptophlebla volitans, Caenis
hilaris, Ilexagenia wecwa, Ephemera11a trilineata, and Tricorythodes albi-
llneatus.
REASONSi Only mature and half-grown nymphs and a single adult are represent
ed in my collection. There appears to be no reason to doubt that emergence
in this species is identical Tilth that of the other Florida species of
Isonychia, and occurs, throughout the year#
HABITS AND LIFE HISTORY: Habits and life history are unknown, but probably
differ very little from other Florida species of Isonychia#
DERIVATION OF TUB SPECIES: Relationships with other species cannot be
derived without male specimens for study; however, the distribution of
Isonychia sp. B would seem to indicate an entrance into Florida by way of
the Apalachicola river drainage system#
LOCALITY RECORDS: Washington Co. Holmes creek (April 2, 1S38, H. H. H.
and L. J. M., nymphs and adult)#


A KEY TO THE MAYFLIES OF FLORIDA


THE MAYFLIES OF FLORIDA
(EPHEMEROPTERA)
By
LEWIS BERNER
A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
June, 1941

/> &
TABLE OF CONTENTS
C)
The mayflies of Florida
Historical review
The problem
The order Ephemeroptera
Primitive and specialized characters
The families of mayflies
The wing venation of mayflies
Taxonomic characters
A comparison of Florida mayflies with the northern fauna 33
Taxonomy 33
Comparative abundance 35
Comparative eoology 36
Comparison of life histories 38
Zoogeography 41
Dispersal of mayflies 45
Climatio divisions of Florida 49
The habitats of Florida mayflies 51
Descriptions of habitats ..# 52
Streams 52
Intermittent creeks 52
Permanent creeks .. 53
Sard-bottom creeks with little vegetation 53
Sand-bottom creeks choked with vegetation .* 54
Silt-bottcm creeks with little vegetation . 55
Silt-bottom creeks choked with vegetation * 56
129675
3
7
9
13
22
25
27

Rivers
56
Stagnant rivers #. 56
Slowly-flowing* deep rivers 57
Larger calcareous streams * 58
Ditches and puddles 59
Roadside ditches 59
Puddles
Ponds 60
Sink-hole ponds 61
Ponds with the surfaoe free of vegetation 61
Ponds with the surfaoe covered with vegetation 62
Fluctuating ponds 63
Temporary woods ponds 64
Sporadic ponds 64
Jerome sink . 65
Lakes 65
Sand-bottom lakes 65
Silt-bottom lakes .*.* 67
Disappearing lakes 68
larojpes* .. 68
The Everglades * 69
SWampS * 71
Cypress swamps * 71
Bayheads * 71
Springs 71
Acknowledgements

A key to the mayflies of Florida
75
Adults #
Nymphs
Stenonama
S* smithae
£* sffiS£
S# proximum *#
Hexagenla *
H. llmnophlla #.#
H# Treem ##
H. orlando .##
wp mmmmammmrnmmmmmtm
H* blllneata *
Ephemera simulans
Campsurus insertus
Oreianthus #
11 Oreianthus sp# No# lw
Siphlopleoton #
S# speoiosum
Isonychia #*
£ Perdido
I# piotipes *'
Isonyohia sp# 5 #
Isonyohia sp# 0
Blasturus #.*
B. internedius
Paraleptophlebia
76
87
100
101
123
127
138
140
151
157
162
165
169
172
173
179
180
185
189
196
198
201
202
203
215

P. volitans
216
P* bradleyl ***<
Habrophlebiodea
II* brunnelpennls .
Choroterpes
C. hubbelll ...*
Habrophlebla *.
H* vit*1*81118
Baetlsoa
B* rogorsl
Sphemerella ***
E* trilinsata
B* apalaohloola *
E ohootawhatohee
e* hirsufca
Tricorythodes
T_* albiliaaatus
Caenis *.
C* diminuta
C. hilaris ***
Braohyoeroue *..
B* maoulatum *
B* infrequent **
Callibaetis **
C* floridanus
224
229
230
244
244
252
252
255
257
266
268
276
281
284
288
290
299
301
318
322
326
330
332
333
C* pretiosus
345

Ace nt re lia
S50
A* ephippiatue t.351
A. propinquua 357
Baetis * 560
B# apinosus *. 362
B australis ** 375
B. interoalarls 361
B* spiethi 387
CentroptHum 396
£ -virldocularis 397
£ hobbsl 405
Cloeon rubropiotun * 409
Cloeon nyssa 414
Pseudooloeon 418
P* alachua 420
£ panrulun 429
_P. punctiventris ... 432
P* blmaoulatus 434
References * 439
Biography-
447


1
THE MAYFLIES OF FLORIDA
Few orders of inseots have been so little studied in Florida as the
mayflies, or Ephemeroptera. The fragile, delicate-winged adults, requiring
special methods of collection and preservation, have not been favorite
objects of entomological study* and the same is true of the small and
often inoonspiouous aquatio nymphs of these insects. The objects of the
present study have been to determine what species occur in Florida, where
they are found, where and how they live, and as much as possible concern
ing their life histories* Four years have been devoted to this endeavor,
in the course of whioh muoh of the state has been examined, about forty
thousand specimens have been collected, nunerous speoies of mayflies have
been reared, and muoh eoological information has been obtained about the
group.
Although the Ephemeroptera include no enemies of agriculture, and
at first glance would appear to have little or no economic importance, such
an impression is altogether erroneous. The entire economy of aquatic life
is intimately bound up with the presence and abundance of mayflies, and it
has been demonstrated time and again that these insects, in both immature
and adult stages, constitute an important item in the diet of many species
of fish, or in that of other organisms that in turn are eaten by fish.
The words of Frison (1935t 284-285) apply with particular force to the
study of the epnemerids. He says "The insect life of our inland streams
[and lakes] affords a most interesting and profitable field for investiga
tion* and the sooner we learn to place and evaluate this fauna correctly,
tne sooner we will be in a position to formulate conclusions and generali-

2
zations of importance in our efforts to understand our aquatic resources
and to fonward their intelligent use."
One of the most beautifully written descriptions of the life and
mating of these insects is given in poetic prose by ¡Villiam Bertram (1794)
in his "Travels through North and South Carolina, Georgia, Bast and West
Florida", in which he refers to the mayflies seen along the St. Johns river.
Nearly sixty years passed before Ephemeroptera were again noted in the
state, when Francis Walker, in 1853, described the tiny Caenis diminuta
from St. John6 Bluff on the St. Johns river. Not until 1900 was the group
once more reported from Florida; in that year Dr* Nathan Banks described
a new species, Callibaetis florid emus, from south Florida. In 1931 Dr. J.
R. Traver described Ilexagenla weewa and Hexagenia orlando from the state.
"Ureiantnus sp. No. 1" was recorded from Florida by Dr. Traver in 1935, and
in 1937 she gave a full description of the nymph. Four additional speoies
of mayflies were described by myself in 1940, bringing the total list in
the literature to nine speoies. In the present paper thirty-eight addi
tional Florida speoies are discussed, sixteen of which are considered to
be new forms. The descriptions of the new speoies must await future publi
cations.
Only a single paper dealing with the biology of Florida mayflies in
any other than a taxonomic sense has appeared. This paper (Berner, 1941)
describes and discusses ovoviviparity in the mayflies of the genus Calli
baetis, with particular reference to the Florida speoies.
The recent book, "The Biology of Mayflies" by J. G. Needham, J. R.
Traver, and Yin-Chi Hsu, has summarized our knowledge of the mayflies of
North America north of Mexico, and brought it up to date (1935). Naturally,

3
there must be limitations to a book of this sort, and a certain number of
criticisms have been leveled at it, some quite unjustified Without a
shadow of a doubt, the book is extremely useful and lias stimulated interest
in this formerly much neglected order The greatest gap is found in the
taxonomic section, which deals almost entirely with the adult insects
The majority of species are described only as imagos, and many of these
only in the male sex, although sexual dimorphism is frequently exhibited
among tixe Ephemeroptera. Nevertheless, the collection of this huge amount
of data between two covers has greatly lightened the task of persons be
ginning a study of this fascinating group of insects
HISTORICAL REVIEW
The history of work on the Ephemeroptera was very thoroughly reviewed
by Morgan (1913), and a brief paragraph alloted to eaoh worker who had
contributed to a knowledge of the mayflies up to 1911 Needham in "The
Biology of Mayflies" briefly disoussed the earlier Ephemeropterists, but
did not attempt any detailed analysis of the present trends in this field.
A large part of the work on North American mayflies has been of a
taxonomic nature, but several important studies on morphology, ecology,
embryology, and life histories have been made Taking tip the account with
the year 1911, to which date Morgans summary extends, the following im
portant contributions deserve mention
J S. Needham published an important study of the genus llexagenia in
1920, dealing with taxonomic as well as ecological problems Taxonomic
studies by this author appeared occasionally from the years 1924-1932,
until his interest in the Odonata came to fully occupy his time However,

4
the great quantities of ata on mayflies that lie had aecuaulated over a
period of thirty-five years were not to be lightly set aside, and these
were brought together in 1935 in "The Biology of Mayflies," of which
Needham is senior author*
Nathan Banks, at the present time, has completely given up work on
the Ephemeroptera, Taxonomic papers were published by him in 1914, 1918,
and 1924.
71 A, Clemens, no longer working with the mayflies, has published
papers dealing with a fairly wide range of subjects* In 1913, 1915, and
1924 he dealt with taxonomy and in 1913, 1915, and 1922 principally with
life histories* His most important paper, "An Ecological Study of the
Mayfly Chirotenetes," appeared in 1917, and is a thorough and very ex>*
lightening pieoe of work. Three other papers by this author disoussed
mayflies in relation to their availability as fish food*
Ann li* lorgan in her more recent papers has treated physiologioal
problems, mainly oxygen relationships* Her first paper in 1911 was tax
onomic with some ecological discussions, and in 1913 she published "A
contribution to the Biology of Mayflies." Her two other papers dealing
with mayflies include a study of venation (1911) and a description of the
mating flight of a South American species of Campsurus (1929)*
Helen E* Murphy has contributed but a single paper dealing with North
American mayflies,and in it she describes the complete life history of
baetis vagans (1922).
G* S* bodds and F. L* Hisaw in 1924 published "Adaptations of Mayfly
Nymphs to Swift Streams," a paper which has proven to be extremely important.
The former author also published a paper on the mayflies of Colorado (1923).

5
R* J. Tillyard (deceased), although publishing almost exclusively
on exotio Ephemeroptera, has contributed to the knowledge of North Amerioan
mayflies chiefly through his elucidation of wing venation and paleoento-
mological work.
F M. Carpenter has recently begun studies on paleoentomology. His
first paper relating to fossil mayflies appeared in 1933
J. A. hostage, of Belgium, has worked principally with European may
flies in a taxonomic sense j however, he has made etudes of certain fami
lies which also occur in North America, and has inoluded our forms in his
discussions.
Georg Ulmer, nearly all of whose publications have been in German,
has worked very little with the North Amerioan fauna. Eis studies have
been entirely taxonomic, and of these his paper listing the genera of the may
flies of the world in the form of a key is most useful. He has described
two genera of mayflies from North America, Habrophlebiodes and Irioorythodes.
Ferris Keave published an extremely interesting study on the migra
tory habits of Blasturus cupidus in 1930* His other work (1929, 1932, and
1934) has been of an ecological nature and has proven to be very enlighten
ing* He is no longer working with the Ephemeroptera.
J. McDunnough has described more species of North American Ephemerop-
tera than any other taxonomist. His first paper dealing with the group
appeared in 1921, and since that date numerous descriptions of new epeoies
have regularly been published. Through Dr. McDunnoughs work, the mayfly
fauna of the northern part of North America is now rather well known, and
its taxonomy appears to be established on a firm basis.
F. P* Ide first published a tsxonomio and ecological treatment of

6
certain Caruadian mayflies in 1930, and since has written two other papers
which are principally of a taxonomic nature* Hist most important contri
butions, however, are his excellent studies on the postembryonic develop
ment of mayfly nymphs and the effect of temperature on the distribution
of mayfly nymphs in a stream* At present, he is conducting quantitative
investigations on the insect fauna of streams with particular emphasis on
the ephemerids.
11. T* Spieth lias published papers of a taxonomic nature within the
last three years as well as studies on the coloration of mayflies and the
rearing of nymphs. His paper on "The Phylogeny of Some Mayfly Genera"
has been exceedingly useful to students of evolution and has aroused much
interest in phylogenetic work among the Ephemeropterists. At present, his
work is mostly taxonomio*
Jay R* Iraver is second only to Dr. MoDunnough in nuaber of species
she has desoribed* Her first taxonomic paper on the genus Hexagenia was
published in 1931, and since then numerous descriptions of new species have
appeared* Dr* Travers North Carolina work was particularly interesting
for it clearly showed just how poorly the fauna of the southeast is known*
One of her most important works is the taxonomic portion of "The Biology
of Mayflies." Her more reoent papers have dealt with exotic mayflies.
The present tendencies among the Ephemeropterists are still taxonomic
to a great extent, but phylogeny, distribution and ecological studies are
beginning to move into the foreground. Because of an awakening realization
of the fundamental importance of our natural resources, ecological studies
of the L'pheaneroptera, as well as of other aquatic insects, will probably
soon overshadow the present taxonomic research, but before such studies

7
can be mad a taxonomic system 7 erected. Such a system is within sight, but until many, many more regions
are thoroughly investigated, a sound and comprehensive classification can
not be attained* Particular emphasis needs to be paid the immature stages,
for it is in the nymplial form that the mayflies spend almost their entire
life, and it is this stage that is important in the economy of waters*
THE PROBLEM
In a study of this nature, it is rather difficult to point to one
particular phase and say, "this is the problem, rather it would be more
profitable to generalize by considering it not as a problem but as a pro
ject which can never be completed, hen one deals with organisms, the con
stantly changing environment and the constantly changing organ1 sms are
factors which are much too complex to be understood in all their inter
relationships. The understanding of the organisms is by far the more diffi
cult, and we, with our present moans, can hope only to secure a superfi
cial knowledge of the workings of living beings.
Go far as possible I have studied the Ephemeroptera of Florida as
living entities rather than as dead, picldod specimens; however, much of
the work necessarily involved the employment of dead insects. Because of
the far greater intrinsic interest in the living rather than the preserved
animal, I have tried to stress the ecology, life histories, and habits of
Florida mayflies. 1 borrow the following from Sells, Huxley, and #ells
"The Science of Life" who in turn borrowed it from Sir Thomas Browns
"Ants, Bees, and Spiders" to illustrate how wonderfully made insects really
ares "Ruder heads st nd amazed at those prodigious pieces of Hature

8
Whales, Elephants, Lromedaries and Camels; these, I confess are the
Colossus and ^ajestic pieces of her hand; but in these narrow Engines
there is no re curious matheaatioks*"
The epkemerids of Florida being so little known, it was certain that
a study of these insects would reveal much that was new The only other
region, in the south that had been at all intensively investigated was
North Carolina (principally frota a taxonomic viewpoint), and since the
fauna of North Carolina is, for the most part, characteristic of mountains
and hilly countxy, it gave little indication of what was to be expected in
tho lowland areas of the more southern Coastal Plain and the flat peninsula
of Florida*
The approach has been from the standpoints of taxonomy, zoogeography,
ecology, life histories, imbits, and phylogeny. All of these fields of
study viere kept in mind throughout the period of research, and in presenta
tion of the results uniformity of treatment of each species is attempted.
However, as would be expected, there may be much information on one species,
while another goes begging* This is the natural result of the relative
accessibility or inaccessibility of the species to a student working from
the University.
In order to determine just which species occurred in Florida, where
each lived, how it lived, and the various features of its behavior and
activities, much travel was necessary, for a relatively small percentage
of Florida species occur within easily available situations near Gainesville*
Great gaps still exist in the information gathered in the western part of
Florida, and only with much further work will these be filled in*
Sinoe the mayflies of tho whole state are included in the study, and

9
since large areas had to be examined in a relatively short time, but few
physical data were secured* This is naturally regrettable but unavoidable.
THE ORDER EPHEMEROPTERA.
The order Ephemeroptera is a natural grouping of primitive,pterygote
insects. In general, the fore wings are delicate, membranous, and triangu
lar in outline, and usually have intercalary veins and many cross veins; the
hind wings are much smaller than the fore wings and may sometimes be wanting.
The wings are normally held vertically over the back when the insects are
at rest* The mouth parts of the adult are vestigial and the alimentary-
tract lias undergone modifications fitting it as an aerostatic organ. There
are ten abdominal segments, and from the posterior end of the abdomen
either two or three caudal filaments arise. The inrush urea are aquatic and
undergo a hemimetabolous development. The mouth parts of the nymphs are
well developed for chewing; they possess two or three caudal filaments;
and gills are present on certain of the abdominal segments, iayflies
aro the only inseots which molt after they have attained functional wings;
prior to this final molt they are spoken of as subimagos.
The imago, or final adult form, can in most instances be easily differ
entiated from the subimago by several characteristics. The wings of the
subimago are dull and grayish, while those of the adult are normally
glistening and irridesceut; the hind margin of the wings of the sub imago
are ciliated while those of the adult (except in the daeninae and Triocry-
t Ixodes) are bare; the body of the sub imago is dull while that of the adult
is glossy; the fore legs of the subixaago are relatively short while they
become much elongated in the imago, particularly the male; the caudal fila-

10
monta are somewhat hairy ant relatively short in the s ubi.nag but usually
lose this iiairy condition and become elongated in the imago; and in the
males which have divided compound eyes, t.iese are loss prominent and rat
her dull in the sub imago and very prominent and glossy in the imago*
The eggs of nearly all mayflies are laid in fresh water, where a vary
ing period is required for development to take place. The freshly hatched
nymphs possess no gills, out with_n one to three molts these structures
make their appearance; the mouthparts, ho.vever, are all present, though
generalized and simple in form, boon the nymphs assume the body shape
and structure which they retain over moat of their nymphal life. In the
few species, the life history of which has been completely worked out,
there are at least tv/enty-five preadult molts,and in most cases more than
tais number are thougl/to occur, some species requiring as many as forty-
five*
The nymphs of mayflies are adapted to their environments in many and
various ways, though they all share certain features in common, such as
gills, caudal filaments, and chewing mouthparts. (A species recently de
scribed by bpieth lacks the molar area on the mandibles). The burrowing
species exhibit some of the moot remarkable adaptive characteristics; in
these nymphs the legs have became flattened, digging structures the
fore legs are used for pushing the silt aside, the hind legs for passing it
back out of the burrow* The frontal process of the head and the greatly
elongated tusks, or rami, of the mandibles first encounter the silt in the
digging process, loosening it so that tue legs may complete the task of
excavation and removing tne material. The gills of theoe burrowers are
feathery and thoroughly penetrated by tracheae, so that there is a par-

11
ticulary efficient mechanism for obtaining oxygen* Even the feeding habits
have become modified to such an extent that these nymphs, much like earth
worms, oat the organio materials encountered in their burrowing; however,
they seem to feed somewhat selectively, since surprisingly little sand is
found in their digestive tracts*
Numerous other distinctive modifications of form and structure are
encountered among those nymphs whioh do not burrow, and they are directly
related to the habits end habitats in whioh the nymphs normally live*
Dodds and Hisaw (1924) have shown that nymphs whioh live on the undersides
of rooks in mid-stream, where there is almost no current, have flattened
bodies, while the bodies of those inhabiting the swiftest waters are tor
pedo shaped* Still others with rounded, streamlined bodies dwell in ponds,
but here it is the ability to swim and dart about rapidly that is correlat
ed with the streamlined form*
I have found that there is a definite correlation between claw size
and habitat* Those species which dwell in ponds and in very slowly flowing
water have thin, attenuated claws whioh lightly touch the object to which
the insect is clinging, but they do not form a strong damp* A nymph
with suoh long claws would probably have difficulty in maintaining itself
in a strong current, for the claws could soarcely have sufficient leverage
to support the insect in this situation* The mayflies living in swifter
currents have short, thick claws whioh clamp firmly into the object on
which the insect i6 living* The stronger the current, in general, the
shorter and thicker the claws* Mayflies from rapids have very short thick
claws, often with strong teeth on the underside, and in one species that
I have examined this pectination has gone so far that the entire tarsal

12
claw has become a comb-like structure and the major claw is no longer
distinct* For the most part, the sise of the tarsal claws is fairly uni
form within a genus, but this is not always so* In one genus, Centroptiluna,
there are two Florida species, one of which (vlridocularis) occupies slowly
flowing, the other (hobbsi) swiftly flowing water* In viridocularis the
claws are three-fourths as long as their respective tarsi, while in hobbsi
the claws are only one-half as long as their respective tarsi*
The nymphal leg structure, even in the non-borrowers, is correlated
with the habitat* Those species inhabiting ponds and relatively quiet
waters have rather elongated limbs which stand out from the body, holding
it above the objeot to which the nymph is attached* The sprawlers have
shorter,thicker legs, the femora being somewhat broadened; the legs are
held out horizontally from the body and do not serve to lift the insect
from the surface on which it is crawling* The dingers of swift water
have thickened, shortened legs with a correspondingly greater development
of the muscles. Their legs are held horizontally with the femora close
to the body; the latter are thin along the anterior edge but relatively
thicker posteriorly, thus presenting lessened resistance to the current*
The caudal filaments show special features in the freely swinaaing
and darting mayfly nymphs* In these species, there is a great develop
ment of hairs medially from the lateral filaments and laterally from the
median filament so that these hairs overlap to form a paddle. By rapidly
flicking the abdomen and holding the tails stiffly, a very efficient swimming
organ is formed and the insects oan move rapidly through the water* Those
species which swim little or not at all have a correspondingly small develop
ment of hairs on the caudal filaments, and in some of these nymphs the

IS
tails are almost bare.
PRIMITIVE AND SPECIALIZED CHARACTERS
It is frequently said that mayflies are primitive insects, and it
is certainly true that many primitive characteristics are exhibited by
this order. Luring the Carboniferous period, or probably earlier, a group
of winged insects evolved a mechanism in the wing base for flexing the
wings horizontally over the back when not in use. The descendants of
this group (Neopterygota) include the majority of modern winged inseots,
while the more primitive nonwing-flexing inseots are represented today by
only two orders (Odonata and Ephemerida), both of which have descended
from Carboniferous times but are not closely related to each other. (Snod
grass, 1935 12). The earliest known fossil insects identifiable as may
flies were taken from Permian shales. These early mayflies were long-winged,
long-bodied inseots with slender lege and three long tails. The fore and
hind wings were of nearly equal size and the wing veins were very well
developed. Fossil mayfly nymphs taken from Jurassic beds in Siberia
seem to have gills on nine abdominal segments.
The fore wings of the more generalized mayflies possess nearly all
the veins of the archetype venation. The costal vein is rather short,
running only as far as the humeral brace, and from thenoe outwards to the
edge of the wingj the fore margin consists of a slightly thickened, folded
wing membrane beyond the costa. The suboosta extends from the wing base
to the apex of the wing, while the radius branohes a short distance from
the wing base to give rise to R^, which runs parallel to the subcosta, and
to the radial sector, which in turn divides. The radial seotor forms Rg

14
Eg, and R¡. plus H5J R4and Eg make up a single vein and the terminology
is used only to prevent confusion The media is represented by both its
primitive branches, the anterior media (lost in the Neopterygcta) and the
posterior media; and the cubitus is likewise represented by the anterior
and posterior cubituB The Ephemeroptera are the only modern inseots in
which both branches of the media presist The number of anal veins varies
from one to three according to the genus*
In the hind wings of the more primitive genera the venation is but little
modified from that of the fore wings; however, with the shortening of the
wing the area occupied by Rs lias become smaller and R3 has disappeared.
The genitalia of mayflies are likewise primitive Irams (1931: 41)
states that "a very primitive condition is found among Ephemeroptera, where
the penis lobes, instead of being fused to fora an aedeagus, are relatively
large and entirely free, with the parameros closely applied to them. A
styliger plate is borne on the terminal ond of the ninth sternum, and for
ceps arise from the posterior edge of the styliger plate The penes are
considered to arise from the ninth segment and protrude between the ninth
and tenth segments "The styliger plate of the mayflies is interpreted
by Crompton and Walker as representing coxites, which have fused together to
form a single struoture. This struoture, however, is separate from the
ninth sternite A parallel condition is to be found, acoording to 'Walker,
in the Phasmoidea and Acridoidea, except that in these groups the styli
are lacking. (Spieth, 1933; 73). The forceps of the male Ephemeroptera
are homologues cf styli, and in all mayfly genera, except Caenis, Brachy-
oerous, and Campsurus, are segmented. In the females, the oviducts open to
the outside or into a common vestibule formed as a fold of the thin membrane

16
joining the seventh and eighth segmente. The sternum of segment seven is
produced backward to form a structure known as an egg valve, but no true
ovipositor is formed} however, in some of the Leptophlebine mayflies there
is the beginning of such a structure (see fig. <3 ).
The abdomen of mayflies, although possessing only ten distinct segments,
is nevertheless considered to be quite primitive. The usual number of seg
ments in the abdomen of modern insects is ten or eleven, but enbryological
evidence incicates that the number of segments of the early insects tob
twelve. The generalized form of an abdominal segment.is approximately re
tained in those larval forms vidoh preserve rudiments of the abdominal
appendages. In mayflies each gill-bearing segment is distinctly divided
into a dorsum and a venter by large lateroventral lobes supporting the gill.
These lobes represent the bases of abdominal appendages. Snodgrass concludes
that there is little doubt that the gills of mayflies are appendicular parts
of abdominal limbs, of which the supporting lobes are the bases* The gill
stalk or gill plate, by its position on the basis and its basal musoulature,
suggests that it is the homologue of the stylus of the thysanuran abdominal
appendages. The gill basis is very evidently the equivalent of the stylus
bearing plates of the Maohllidae, though since it is immovable, there are
no body muscles inserted upon it." (Snodgrass, 1935s 273).
In order to arrive at any conclusions as to the primitiveness of the
moutliparts of the Epheraeroptera, it is neoessary to turn to the nymphal stages.
The mayfly mouthparts are of the mandibulate type throughout the order,
consisting of a labrum, hypopharynx, a pair of mandibles, a pair of maxillae,
and a labium. The mandibles of most mayflies are very generalized in possess
ing a ventral incisor area and an inner or dorsal molar surface. Between

16
the incisor and molar areas there is a small structure called the lacinia
mobilis, the function of whioh is unknown.* This structure has been inter
preted by some as a mandibular palp and a prostheca, but according to
Crampton it cannot represent a true palp* This author has suggested that
the mandibles of mayflies in some respects approach those found in the
Crustacea. Attached as lateral lobes of the hypopharycs, are a pair of super
linguae* Supsrlinguae are best developed in apterygote insects and in some
of the more primitive members of the Pterygota. The galea, lacinia, stipes,
and palpifer are fused in the maxillae of all modem mayflies, and form a
structure called the galea-lacinia* In some of the more primitive genera
it is though that & line of separation can be seen between the galea and
lacinia* On the whole, the maxillae of mayflies must be considered as rather
specialized*
The primitive condition of the tarsus of adult pterygote insects is
thought to be five-segmented; tarsi having fewer than five segments have
probably been specialized by the loss of or fusion of some of the segments*
In the adults of some of the more primitive mayfly generea, the tarsi are
composed of five freely movable segments, but in most mayflies there is a
certain degree of fusion* The legs, therefore, cannot be used as reliable
indicators of phylogenetic position of the Ephemeroptera among the other
insects*
The gills of mayfly nymphs are thought to be homologous with abdominal
legs appendages which have been modified for respiratory purposes. Snod
grass states that there is no question but that the gills arise from limb-
libs rudiments of the embryo, and that their structure and musculature suggest
that they are parts at least of true abdominal appendages* The most primi-

17
ti ve of the modern mayfly genera bear ills on the first seven abdominal
segments* and the earliest fossils known had these structures on the first
nine segments. The retention of these abdominal structures appears to in
dicate primitivenese, even though they are present in highly modified and
variable forms.
A consideration of the characters discussed above will also show that
mayflies, while generalized in many respects, are at the same time highly
specialized in oertain features* As Needham (1935s 207-208) has said, "The
group as a.whole, while retaining a good many primitive characters, has
gone a long way in specializing on lines of its oiwn There arc no very
primitive mayflies. There is no one genus or species that can be set down
as nearest to the ancestral form in all particulars. The lines run criss
cross here as elsewhere, and do not lend themselves to a serial arrangement."
One of the principle modifications and specializations undergone by
the wings has been the oephalization of the flight mechanism, with relative
enlargement of the fore wings and corresponding reduction of the hind wings
until, in scsie genera, the latter have entirely disappeared. In the specializ
ed genera venation tends to become reduced, and oertain of the longitudinal
veins become detached and may even be shifted at their bases and reattached.
Paralleling this modification of the longitudinal veins, there is a tendency
toward reduotion in the number of cross veins in the fore wings, until
in tiie highly specialized genera they may be almost completely absent. At
the same time that the cross veins are becoming reduced in number, a series
of marginal veinlets develops, occupying the interspaces between the longi
tudinal veins. The presence of these veinlets is a mark of greater specia
lization than the irregular marginal network (the remains of the archediotyon)

18
found in the most primitive mayfliesj in the higher genera even the vein-
lets may he lost*
The hind wings indicate degree of specialization very clearly, for in
the Ephemeroptera there exists a whole series of species ranging from
those with well developed metathorado wings to those showing complete
absence of such structures* In certain of the highly specialized groups
the hind wings are reduced to tiny threadlike rudiments, sometimes so small
as to be difficult to find, and which could hardly be of any use as organs
of flight. The venation of these threadlike wings consists only of one to
throe longitudinal veins*
The form of the fore wings in the primitive genera of Ephemeroptera is
somevrhat triangular# With increasing specialization, they have become more
elongate and narrower, but in those genera with greatly reduoed hind wings
there is a tendency for the secondary development of a triangular wing with
a well developed anal angle, perhaps in compensation for the partial or
complete loss of the hind wing* The return to a triangular wing shape reaches
its culmination in the highly modified Caeninae, which completely laok
metathoracic wings*
Mot only is there a correlation between specialization and reduction
in size of the metathoracic wings, but closely linked with it, body size
likewise seems to have decreased* It is very likely that as wing size de
creased a diminution in body size was a natural consequence, or the reverse.
The amount of wing surfaoe for support of the insect being lessened, the
necessity for less body weight or an increase in wing surfaoe of the other
pair of wings was encountered. Both conditions have resulted. A diminution
of body size parallels the diminution in size of metathoraoio wings, with

19
concomitant changes in shape of the me sot horade wings but no relative in
crease in resulting wing surface# In Gaonis, which lias entirely lest the
hind wings and in which the body is thick and heavy by comparison with that
of the Baetinae, the fore wings have become enlarged and broadened consider
ably at the anal angle# Although certain other genera of mayflies have
lost their metathoracio wings (Pseudooloeon and Cloeon), there has been no
such relative increase in sise of the fore wings, but the body is lightened
to accomodate the lessened wing surface#
There are few specializations in the genitalia of mayfliesj however,
in the more advanced genera there appears to be a fusion of segments of
the forceps, and in Caenis and Braohycercus this has reached its culmination,
the claspers consisting of but a single segment# The males of the more
specialized species also show a fusion of the paired penes, although the
vasa defferentia still open to the outside separately, and in the Lae time
the penes have become internal#
Although the Leptophleblinae are not the most highly specialized may
flies, certain of the females have the sternites of the seventh, and eighth
segments modified to form a simple ovipositor. The ovipositor is really
nothing more than a prolongation of the egg valve of other mayflies, arid its
value in oviposition is entirely unknown*
All mayflies supposedly have ten abdominal segmentsj however, in Baetisca
and the European Prosopistoma there seoms to be some amalgamation of the
segments, although it is claimed that ten segments can be distinguished*
The first abdominal segment of Baetisca is intimately related to the meta
thorax, and it is only with difficulty that this segment can be differentiated#
Spieth (193T) considers that in the nymphs of Baetisca gills are found on

20
segments one through five, but Traver (1935) claims that these structures
occur on segments two through six. The latter author stttes that segment
one is almost completely fused with the thorax, a statement with which I
am in agreement. Thus this condition of lessening of number of abdominal
segments, although indicating specialization, is found in a genus which has
many primitive characters.
Specializations are not pronounced in the mouthparts of immature may
flies, but the degeneration evinced by adults is oertainly a highly modified
condition existing in relatively few insects. The mouthparts of the adults
are reduced in size, asymmetrical in form and lack chitirdzaiion. Internally,
the lusoulature degenerates. As a whole they are shrunken very closely
together in a single whitish mass beneath the clypeus. The greatest modi
fications in tlie nymphal mouthparts occur in the burrowing spe oies, where
each mandible gives rise to a long tusk used in digging (fig. 1The
fusion of the parts of the maxillae indicates a specialization in these
structures. Spieth states (1933: 81) that "even the most primitive maxilla
of the mayflies (as is patent from the nature Of the lacinia-galea) is
specialized a3 compared with more generalized insect types."
one of the most interesting specializations undergone by mayflies is
in the enormous development of the eyes of males. In the Baetidae the
compound eyes of the male have become completely divided into two parts,
a lower rounded structure and a much larger "turbinate" portion capping
the smaller part. The oramatidia of the turbinate eyes have become greatly
elongated, and the shape of these eyes is gre tly varied, ranging from a
cap-like, flattened structure closely hugging the lower eye tc one which
extends vertically from the head for some distance. In many species the

21
turbinate eyes are brightly colored in shades varying from yellow to
orange to brown. It is thought that this exceptional growth of the eyee
of the males is correlated with the habit of aerial mating, for in this
flight the male approaclies the female from below* It has been pointed out
by Cooke (1340) that the specializations have reached such a state of devel
opment that if a male (of btenoneua vioarium) be approached by a female
from below, she will be completely ignored, probably because she is in
visible to the male; however# if the female is above the male, she is
ira -: diately seized and copulation ensues*
The legs of mayflies, although primitive in some respeots, are really
highly modified organs* Adult mayflies do very little walking and no
running whatsoever* In certain groups, i. e* Campsurus, the legs (except
the fore lags of the male) have became vestigial, and the adult can no
longer alight but xaust remain on the wing during its entire ia&ginal life*
horgan (1923: 63), in her description of the mating flight of C segnis,
states that "in the extreme specialization which Campsurus segnis has at
tained the brevity of its aerial life has been a necessary parallel to the
abbreviation of its legs. The adults are entirely dependent upon their
wings for existence* Since they have no legs to rest upon neither males
nor females can alight upon anything and if they are forced down there is
little chance that they can ever fly again*" The forelegs of male mayflies
are elongated and have been provided with a reversible joint at the base
of the tarsus as specializations for seizing the female during the mating
flight. The mere specialized mayflies show a tendency toward a reduction
in number of tarsal sequents in the two posterior pairs of legs by fusion
of the basal segments with the tibia.

22
The alteration of the alimentary tract to suit it for its aerostatic
functions is a character common to all mayflies, and it is one which in
dicates a specialization throughout the order# The modification of the
raouthparts, the tremendous development of the ovaries, the enlargement and
emptying of the alimentary canal, the enormous development of the eyes of
the males, the elongation of the fore legs of the males, and the develop
ment of elaborate oopulatory organs all fit the adult mayfly for efficient
mating and the certitude of continuing the species#
THE FAMILIES OF MAYFLIES
There have been many arrangements of mayflies in various families
and much buffeting back and forth of the genera# As yet, there 6 no
general agreement as to what constitutes a family and what constitutes a
subfamily in the Ephemeroptera# For the sake of uniformity, I shall follow
the taxonomic system set forth by Needham, Traver, and Hsu (1955) in which
three families of mayflies are recognised to occur in North America, north
of Mexico#
Family Ephemeridae^
Subfamily Ephoronlnae
" Ephemerinae*
n Potamanthinae
" Gampsurinae*
" ~> Neoephemerinae*
Family Heptageniidae
Subfamily Heptageniinae*
1# An asterisk after the subfamily name Indioates that representatives are
found in Florida#

23
Family Baetldae
Subfamily Ametropinae
" ~ Metretopinae*
" Siphlonurlnae*
" Leptophlebiinae*
" Baetiacinae*
" Epheme re11inae*
Caeninao*
" Baetinae*
Ulmers key (1933) to the Ephemeroptera of the world lists three sub
orders, Ephemeroidea, Baatoidea, and Keptagenioidea and these in turn are
divided into fourteen families* These families of Ulmer* however* in some
oases* do not coincide with the subfamilies of Needham and Traver* Spieth*
also in 1933* used superfamilies in his discussion of the phylogeny of
North American mayflies, and included his genera under the following: Super-
family Siphlonuroidea* including the families Siphlonuridae* Heptageniidae*
Baetidaej Superfamily Ephemeroidea, including the families Leptophlebidae,
Sphemeridaa, Ephemerellidaej Superfamily Caenoidea, including the family
Caenidae} and Superfamily Baetiscoidea* including the family Baetiscidae*
Chernova recently (1938) described a new family of mayflies from Russia* but
I have been unable to secure a copy of this work and can give no information
about the groqp*
The usage of the terms suborder, superfemily, family* and subfamily as
higher categories appears to be merely a matter of convenience subject to
the whims of eaoh particular worker* However* consistency in usage would
seem to be desirable, and whether the tern family or subfamily is used to

24
designate these categories is a matter of choice. The taxonomic system,
i. e. the higher categories, set up by Needham and Traver appears to be
adequate in the present status of our knowledge.
As far as the inclusion of genera within the families and subfamilies
is concerned, muoh more phylogenetic study is necessary before the positions
of several of these groups can be satisfactorily determined. Certain genera
exhibit characteristics which would plaoe them in either of two subfamilies,
and in such cases it is desirable to indicate this overlapping in discussions
of these genera. In reality, there are no genera of North American mayflies
which cainot be placed rather definitely in the higher categories, except
perhaps Isonychia, which has been included both in the Heptageniidae and
Bastidae* In this paper, Isonychia is considered as blonging to the
Baetidae, but the placement is debatable.
Ulmers 1933 key to the Ephemeroptera of the world included one hundred
fifteen genera, and sinoe the publication of this work several generic changes
and additions have been made. At present, forty-nine genera are recognized
as oeourrlng in North America, north of Mexico. Sinoe the publication of
"The Biology of Mayflies", Aoentrelia has been re-erected, and Oligoneuria
has been discovered in the drainage of the Mississippi*
When Traver wrote her taxonomic review of the mayflies of North America
in 1935, she included five hundred seven species. Since the publication
of tide work, forty-two additional speoies have been described from the
region. There are still numerous areas on the North American continent
which have barely been touched, and when these are finally worked many more
undescribed species will, without doubt, be discovered*

25
THE WING VENATION OF MAYFLIES1
The wing venation of mayflies has recently been reviewed by Spieth
(1933) and by Needham (1935) These two authors disagree in their inter
pretation of one important set of veins* Needham and his followers con
sider tne radius to be divided into R1# Rs, Rg, Rg, and Rg, and that
the anterior media is missing from the wings of modern ephemerids. Till-
yard, Carpenter, Spieth, and others adopt the view that the radius is
divided into R^, Rs, Rg, % and % plus Rg, sind that the anterior media
is present* The essential difference between these two views rests upon
the interpretation of the homologies of one vein in the mid-wing,which
divides to produoe two branches* Needham has named this branched vein
the outer fork of the posterior branch of the Rs (OF), while Tillyard
and his supporters consider it to be the anterior media* In the present
paper the term anterior media is used to designate the vein in question*
In all other respects, there is full agreement between the two groups of
workers concerning the generalised nature of the venation of mayflies*
Mayflies are unique among pterygote insects in completeness of fluting
of the wings* There is a regular alternation of high and low veins, or
convex and concave. A very important feature of the mayfly wing is seen
in the relations of the veins as shown by Spieth, all convex veins
belong to the dorsal surface of the wing and the oonoave veins to the ven
tral surface. "The cross veins blong principally to the dorsal surface,
i* *, at the base where they join the concave veins a stump of the cross
vein is attached to the main vein, while on the dorsal surface the cross
veins are always complete and vigorously developed...* It is important to
note that veinlets at the edge of the wings are always restricted to the
1* The names of wings veins of mayflies have been disoussed on page* P'tf

26
dorsal surface." (Spieth, 1933; 60).
The triadic type of branching is also a characteristic feature of
mayfly venation. When a longitudinal vein forks, there is interpolated
between the two branches a third vein of opposite position, which does
not reach the base of the fork. For example, the anterior media, a convex
vein, forms a fork just beyond the middle of the wing (called the outer
fork [OF] of the radius by Needham). The two branches of this fork are
convex} however, the intercalary vein lying between the two branches
is oono&ve. This system of fluting is primarily an adaptation for radial
strengthening of the wing, and the cross veins serve chiefly to hold the
ridges and furrows in place. In the more specialised mayflies, which have
small hind wings or none at all, there is a decrease in the number of
cross veins while in those speoies which have large wings with prominent
fluting, the oross- venation is well developed. This system can be seen
to reach its maximum in Ephoron in which there are several hundred cross
veins in the fore wings*
The origin of the various wing veins lias been studied principally by
proponents of the Needham system* hr* Ann Morgan (1912) conducted a
rather intensive investigation into the origin of the definitive adult
venation} but in the light of further research by Tillyard and others,
some of her results have been found to be erroneous. One of the most
outstanding pointB of disagreement is that while Morgan interpreted the
radial sector and media in the same manner that Needham had interpreted them
in Odonata, showing Rs crossing the media, more recent studies lend no
support to this interpretation. There is a complete review of wing traohea-
tion in "The SicJogy of Mayflies*"

27
TAXONOMIC CHARACTERS
Perhaps taxonomists have not been sufficiently thorough in their
treatment of mayflies* All structures or features that have been used
taxonomically are external; until students of mayflies overcome their
inordinate desire of preserving perfect specimens, the approach study
of internal anatomy will not be used* Of course, the difficulties involved
in an investigation of the internal anatomy of small organisms must also
be taken into consideration, and when large numbers of individuals are to
be examined such studies would obviously be out of the question* Further
more, although it might be thought that taxonomic studies carried on for
so long a time as has been the oase in Ephemeropteran work would have
resulted in a very thorough knowledge of the external morphology of the
insects j however, there are structures which are still imperfectly known,
even though they are used to a great extent in taxonomic work.
Of primary importance in the separation of families, genera, and even
species, the wing veine of mayflies are even now not satisfactorily under
stood from the standpoint of homologies* The problems of venation have
been discussed above in the considerations of phylogeny and venation* The
wing veins of each genuB of mayflies, and in particular the longitudinal
veins, air very constant in struoture and position so much so that only
in few groups can specific differentiation be found, and then only by re
ference to minute details* Eaton (1883-1888} 4), in his monograph, has
clearly summed up this situation "Unstable in minutiae, so closely is the
essential plan of the neuration adhered to by nearly related Mayflies, that
the general facies of the wings is an important aid to their classifica
tion, affording characteristics as easily recognizable as the style of

28
branching in the case of trees." The highly modified hind livings are very-
useful in differentiating genera -Hithin the various subfamilies and,in many
oases, the shape of the costal angulation, the number of longitudinal veins,
and the general wing shape and relative proportions of these wings are
helpful even in distinguishing species.
The structure of male genitalia has been widely employed by taxonomists
throughout the field of entomology and even in the study of other animals*
These reproductive structures are particularly useful in the differentia
tion of ephemerid species, and have been widely applied, Many of our
present species have been established on genitalio differences alone, but
there are usually other characters which parallel such genitalio diver
gences. haoh genus has its own peculiar penial shape, and within the
genus there may be much variation. Lne of the best examples of this is
seen In Paraleptophlebia, where eaoh species has a distinctive type of
penes* The shape, number of segments, and relative proportions of the
forceps or claspers are also very useful in differentiating genera, and
in some cases species* The reproductive apparatus of the female mayfly
is so poorly developed externally that it is of no use taxonomioally,
except in those few genera which possess a rudimentary ovipositor*
Dr* Osgood biaith made a study of the eggs of a number of genera of
mayflies, and found that within a genus the sculpturing and accessory struc
tures are very uniform. From his study, he was able to construct a key to
the known eggs of Forth American mayflies, and this key has been incorpor
ated in "The Biology of Mayflies*"
The number of tarsal segments in the posterior pair of legs of adult
mayflies is a character which has proven useful as a familial differentiator*

28
Within some families, the length of tarsal segments of the fore legs of
the males is used to distinguish between genera, and in some oases this
character has been relied on to suoh an extent that it is impossible
to identify a female to genus, unless males can be definitely associated
with her* It seems that much further work is needed in these groups
in order to clarify the situation* Within the genera, leg structure
is little used taxonamically, although 1 believe that relative proportions
of the various parts will prove useful when measurements are made*
Another character frequently used, and rightfully so, is eye struc
ture, but tills character again is applicable only to males* Sexual
dimorphism in mayflies is so very pronounced that unless one is familiar
with the group, males and females of the same species might easily be
mistakenly placed in different genera* Among the male ephemerids, there
are all gradations in structure of the oompound eyes from a simple type
to those which are completely divided and enormously enlarged into bizarre
shapes* Whether or not the eyes are divided is used as a criterion for
separating the Baetid&e from the Heptaganiidae, and in some oases the
character is also used as a generic differentiator* There appears to be
a definite correlation between eye sise and shape and the night- or dagr-
flying habit8 of the species* Those mayflies mating at dusk or after
dark have small eyes which are approximately of the same size in both
sexes, or but slightly larger in the males* In Palingenia (European)
the female is approached by the male as she floats on the surface of the
water, and in this genus, the eyes of the male are a little smeller than
those of the female* The males of the day-flying species have huge eyes
which are far larger than those of the females*

29
The colors found in mayflies vary from white through yellow, orange,
red, brown, to black. All these colors are rather drab, and aid in
making the mayflies as inconspicuous as possible. Spieth has pointed
out that the more primitive species have particularly dull and subdued
colors. This author found that in the greater number of mayflies the
entire exoskeleton is transparent, and if oolor is present in the chitin,
it is always ecrne shade of olive brown. The tissues immediately under
lying the exoskeieton are often impregnated with pigments whioh are the
principal cause of the distinct adult color pattern. Dr. Spieth found
that the wnite oolors in the Ephemeroptera are due to two distinct fac
tors: (1) in all adults, a chalky white substanoe is present underneath
the exoskeieton and the epidermis but external to the musculature (2)
certain speoies have a milky appearance whioh ooours not only in the body
but also on the wings of some species. This is a physical oolor, whioh
disappears when the insect is immersed in liquids of the same refractive
index as that of the white structure. The two types of white combine to
form the color pattern of those adults showing this seoond type of color
ation* He also points out that some of the oranges, bright yellows and
greenish yellows present in certain species are probably chlorophyll
derivatives, since they deteriorate in dried specimens and are completely
destroyed by preservatives.
The disposition of pigments in sexually dimorphic speoies is par
ticularly interesting. The wings and body of both sexes of these forms
are brilliant* In the males, however, the pigments are no longer evenly
distributed in each abdominal segment but are concentrated in the first
and the last four, with the intervening ones hyaline white. There may be

30
a definite color pattern overlying the white of segments 2-6, but this
is never conspicuous* In nearly all cases, this strongly localized
coloration is limited to specialized genera of mayflies which are less
than ten millimeters in length* It is probable that the glistening wings
and the hyaline sequents help to render the insects inconspicuous because
there is euoh a great reduction in the amount of dark color exposed to
the view of predators* The females of these species have uniformally
colored abdomens, but it has been suggested that if the entire exoskele
ton of these insects were transparent, the light colored musoles as well
as the egg masses would show through and the females would be easily seen*
Differences in maoulation are reliable, in general, for distinguish
ing species, biit the great degree of variability in some species causes
misgivings whenever color pattern, unless it is absolutely distinctive, is
used* The genus Stenonama is one of the chief groups in which color has
been used for the establishment of new species; however, it should be
employed with caution* In Florida,a species of Stenonema occurs which by
its color pattern might fit into any one of three species, S. proximum
(the name used for it in this paper), S* pallidum, or interpunctatum.
Probably (just as was found to be true of S* tripunotatum, described below)
S* proximum and pallidum will prove to be local variants or seasonal forms
of S* interpunotatum*
To distinguish between species, oolorationai differences have probably
been employed more than any other character or group of characters*
Spieth (1938) made a study of coloration and its relation to seasonal
emergence in the Ephemeroptera, and from his study it appears that some
of the species, which have been described solely on the basis of maoulation-

SI
al differences, are really only seasonal forma of the sane species
I have been told by Drs Spieth and Lyman and Mr Jenkins, who have
worked in the Great Lakes region, that,as an example of this,Stenonema
tripunctatun shows seasonal variation in coloration exceptionally well
Dr* Traver has described several species differentiated from S tripunc-
tatum by ooloratlonal variations, but the other workers mentioned above,
through observations during the entire emergence period of the mayflies
of a particular region, have found that all of these are seasonal forms
cf the one speoies*
Size of adults, including both wing length and body length, has been
used to some extent for species determination; however, so many factors
modify 6ize that it is not considered a safe criterion by itself for the
erection of species Wing length within a population is much less variable
than is body length, for the latter is subject to shrinkage, elongation,
swelling, etc when the insect is killed There has been very little use
of relative proportions of wings fresa a taxonomic standpoint, but this
may be worthy of future study*
The families of mayflies as they are set forth in this paper appear
to be natural groupings, for the evidence from the adults is substantiated
by the structure of the immatures. Needham (1935* 208) states in this
order the struggle for existence has fallen largely upen the nymphs, which
are better equipped to meet competitors These show greater divergences
in adaptation to their several types of habitat These have differentiated
on lines of their own, independently of the adults, and tell their own
story* It goes without saying that out interpretations of nymphal and
adult evolution will, when correct, be in agreement On must corroborate

32
the other; for nature preserves or eliminates species as wholes."
Mouthparts and head shape are the familial characters used to separ
ate the families of mayflies in the nymphal stages. The subfamilies,on
the other hand, are to a large extent separated by the structure of the
mouthparts and the structure of the gills, of which the latter are probably
the more important.
3ill shape and structure are extremely varied. They may be foliaceous,
six-gle or recurved; they may be highly traeheate or completely lack these
air tubes; they may be present on seven abdominal segments or they may
be absent from some of them; they may lie flat on the abdomen or they may
be so shifted that they serve as suckers on the venter of the insect;
they may be modified so that some fom protective covers for others or
they may be completely exposed; they may be strongly muscled so that they
can be vibrated very rapidly or they may be so flabby that such reactions
are out of the question; they may be entirely confined to the abdomen
or, in a few oases, gills may also ooour on the thorax or even on the
maxillae. In short, the gills are probably the most variable structures
to be found in the nymphal Ephemeroptera.
Since hind wings are absent in the adults of some species of mayflies,
naturally their iramaturee lack hind wing pads* The presence or absence of
these metathoraoio wing pads is used as a taxonomic character whenever
possible.
The caudal filaments, two cerci and one median tail, are very use
ful in studies of the nymphal forms. In some species, these are vexy
flexible organs, while in others they are sturdy swimming structures. The
cerci of many of the genera are densely clothed with hairs medially and

33
the media tail of these genera has heavy growths laterally; in many
others, the three tails are almost bare, having only a light covering of
short hairs*
Color pattern, while frequently used for species determination, is in
no wise as frequently employed as in the adults* Often when suoh charac
ters are found to distinguish species, sturctural differences parallel
them*
A COMPARISON OF- FLORIDA MAYFLIES WITH THE NORTHERN FAUNA
Taxonomy
The genera of mayflies ooourring in Florida, except Oreianthus, are
found over the entire eastern part of North Amerioa, and even Oreianthus
is known as far north as North Carolina* It is of interest to note that
many of the genera suoh as Ephemera, Choroterpes, Habrophlebia, Kabrophle-
biodes, Pseudooloeon, and Trioorythodes have never before been reoorded
fresa the Coastal Plain, but all of these are now known to occur in Florida*
Trioorythodes was previously taken no closer to Florida than Texas and West
Virginia, while Choroterpes me recorded only as close as Texas and northern
Ohio*
Thirteen of the Florida speoies are found also in southern Canada,
Chio, and New York as well as other areas in the north* In addition, there
are several other speoies which are very similar to those described from
the northern region but which differ in minor oolorational or genitalial
characters# It is to be noted that all but one (Bexagenia bilineata) of
these wideranging species are small forms* This conforms with the general!

34
tion (for which no explanation is at present forthcoming) that the smallest
mayflies are, on the whole, the most widely disseminated a generaliza
tion that seems to be world-wide in application
Fifteen species hitherto unknown are here recorded from the state, but
nine of them are known only fresa the nynphal stage. In addition, four
new Florida speoies have recently been described making a total of nineteen
species discovered during the course of this investigation. The total faunal
list of forty-seven species from the state seams large for such a small arid
(from the standpoint of mayflies) ecologically limited region.
Actually, Florida is poor in number of species compared to those areas
which can boast of mountainous, hilly, and coastal regions all within
relatively small boundaries. Traver, investigating the mayflies of North
Carolina, found more than one hundred different species in the state, but
her collections included specimens from three physiographic provinces*
Ide (1935) working in Ontario found fifty-five speoies in on stream, and
I have been informed that subsequently he has taken more than one hundred
species from a single stream. No suph concentrations of species are found
in any Florida stream; conditions do not compare in favorability, in these
streams, for mayflies with the rapid, rocky, and well-aerated streams of
Ontario. In our most populous streams the maximum number of species found
is only nineteen, and even this is exceptional (Sweetwater Creek, Liberty
county).
In summary, it appears that the Floridian Ephemeropteran fauna is
mostly of southern origin; however, there are certain northern elements
which have entered the region and which have there succeeded remarkably well.

35
Comparative abundance
In Florida the actual number of individual mayflies that are pre
sent in a given situation is smaller than that found in northern streams*
This faot finds a partial explanation in the relatively small number of
suitable mayfly habitats in any particular stream; however, there is a
difference in abundanoe even in corresponding situations* I have examined
mountain crooks in the southern part of North Carolina, and on the undersides
of roces the number of mayflies found greatly exceeded the number 'which
might be found in analogous situations in Florida* It is necessary to
employ the tena "analogous situations" because in Florida the rook habitats
are only rarely present, and the insects use as substitutes submerged logs,
boards, etc*
In the smaller rivers and streams descending from the mountains along
the east cqast of Mexico, the number of individual insects on a single
rock is amazing* Nearly two hundred mayflies were taken from one rocls^
approximately 15 x 15 x 8 inches, and one the same rock the caddisfly oases
and blaokfly larvae literally covered the surface* Ihen a Florif tre-r-
is compared with such a river, it can be seen that, even though mayflies
are the predominant inseots, they are so much less abundant that they can
in no wise be as important in food chains as those of the rooty streams
of the north and of Mexico*
Adults of the great majority of Florida species emerge throughout the
year, and for this reason there are no great swarms (except in some of the
burrowing forms). The flights are small, composed of Inconspicuous Insects
which gather in groups to mate* The literature indicates that many of the
small northern forms collect in very large swarms to carry on their mating

36
flight, but in the areas where such flights occur, the emergence of those
species forming the large swarms is limited, to a short period. It has been
stated that those species which emerge over a long time the entire sum
mer vri.ll not form large flights, ajad from these accounts it would seem
that in size the flights resemble those of the Florida aphemerids.
The burrowing species,being more or less seasonal, emerge in great
numbers in Florida hut not in swarms ocmp&rable to those described as
occurring in the more northerly parts of the oountry. The lake species, in
particular, during their emergence period do form a conspicuous part of the
insect fauna in the Central Highlands of Florida, and at this time very
likely are Important in the food chains of lakes. The number of individuals
in the lakes approaches more closely the abundance characteristic of northern
regions, than does the number occurring in ary other situation in Florida.
However, the anta Fe river might perhaps compare favorably in this respect
with some northern streams.
Comparative ecology
Naturally, the eoological factors are the most important conditions
affecting the distribution of ephemerid species. As indicated above, those
habitats suitable for northern mayflies are, for the most part, absent in
Florida. Temperature is probably the most important single factor determin
ing the presenoe or absenoe of a species, and current is tied up very closely
with this. The great majority of mayflies are rheooolous, and, as Ide has
shown, the entire stream fauna is very much affeoted by thermal conditions.
This author has stated that the number of speoies inoreases downstream due
to the higher temperatures which prevail in the lower parts of the stream,
and the addition of speoies in this way is more rapid than the elimination

37
of species by high temperatures. His analysis of an Ontario stream in
terms of temperature is very interesting; but although no such tempera
ture studies have been made on Florida streams, Ides results are not
applicable to them because the temperature is uniform throughout the stream.
Iiis conclusions might also lead to the idea that the greatest number of
mayfly species should be found in the southern part of Forth America, where
higher temperatures occur throughout the year, but,as was pointed out above,
the reverse is true.
The rate of flow of water is also an important factor influencing
the distribution of mayflies, but even though there are numerous streams
in northwestern Florida which have a constant and fairly rapid movement,
many species wliioh occur in Forth Georgia and North Carolina are not found
in them. The interpunctatum complex of Gtenonsma is represented in Florida
by a single species, and this complex (perhaps even the same species that
occurs in Florida) also is found in the mountainous streams of North Caro
lina. Iron likewise is found in these North Carolina streams in identical
habitats with the Stenoneraa nymphs. Yet, for some unknown reason., ~;-"r
does not seem to be distributed south of the Atlanta region in Georgia.
The degree of tolerance may be greater in the Stenoneraa species, or per
haps there may be certain differences in feeding habits which would pre
vent the spread of Iron.
Habitats v/ithin Florida streams are apparently more limited in extent
and variety than in northern ones. A great many of the northern streams
*
N \v
are filled with rooks and pebbles, and this condition evidently affords
the optimum circumstances for great numbers of mayfly species. Combined
with the rocks are, of course, pools, vegetation, debris, and many other

36
situations -which offer refuges to the mayfly nymphs* Florida streams,
)
devoid of rooks and with much barren, sandy bottom can offer little in
comparison, even though in these streams all available habitats are utilized
Perhaps the greatest barriers to the wide dispersal of northern may
flies in Florida are the wide areas in which there are no constantly flowing
stream8* Thousands of square miles of the state, particularly in the
coastal regions, are low and flat, and the grade of the lowlands is not
sufficient to maintain permanently flowing creeks and rivers* Typioal
meotropic species cannot exist for long in standing water, and even if
a species were accidentally introduced while there was some flow, &s soon
as the flow ceased, the :.ymphs would probably die The dry, sandy scrublands
of southwest leorgia and of Florida also offer a serious barrier to less
vagile species, and this has probably helped to keep the number of mayflies
in Florida less than that of neighboring states and the northern part of
the continent. Rogers (1S33) found that the save conditions affected the
distribution of craneflies he states "one of the most important barriers
to the northern groups, the ranges of which extend into the Piedmont Province
of Georgia and the Carolinas, is the monotonous, low pine-lands of the
southern coastal pla in with their dearth of clear fairly rapid, pebble-
bottom streams*"
Comparison of Life Histories
Many differences in behavior would be expected between the mayflies
of the north and those of the south, but the most striking are found in
life histories. Those species of Ephemeroptera which are known to oocur
both in Canada and in Florida show wide variations in emergence period, and
sight in consequence be considered different physiological subspecies. In

39
Cenada and the northern states, all of those species have a rather limited
period of emergence during late spring and summer* but in Florida such is
not the case* Here* every one of the species common to both north and south
emerges throughout the year except during the cold spells, and mating
takes place at any the of the year, unless cold -weather is encountered,
when the insects become lethargic*
Although Spieth had no definite information on the point, he stated
rather accurately (1938cs 214) that "in the southern paid: of the United
States, the length of the emergence period of the group is much longer*
There seems to be no reason why in the tropics and subtropics there
should not be some species merging during each month of the year. The
greater part of Florida cannot be considered subtropical, yet Spieths
conjecture holds true for the whole area*
This author (Spieth, 1938cs 214) mates one statement whith which I
cannot agree* "Regardless of the time of emergence during the year, each
species has a definite limited period of emergence. In those species
which have more than one generation each year, naturally there is more
than one emergence period* Usually the period of emergence is relatively
short." In Florida, the period of emergence of the great majority of
species is not at all limited, although there may be many broods emerging
during the year* I do not believe that results obtained in the north, upon
which Spieth based his conclusions, can be accurately applied to the species
inhabiting Florida.
Not only are many of the mayflies non-seasonal in Florida, but this
has beer, found true of otter groups of animals as well. Professor J. S*
Rogers has told me that the life histories of many craneflies are not

40
seasonally limited in Florida whereas tney are definitely so in the north;
tais uas been found to be particularly true in the southern part of the
peninsula.
Reference to the accompanying temperature map (fig* 1) will show that
average temperatures in Florida are suitable, even in winter, for the adult
stage of insects which are primarily of northern origin*
There are very few Florida mayflies which are definitely seasonal and
those few are probably southern in origin, while those speoies emerging
uiroughout the year are northern forms which have immigrated into Florida*
This agrees with observations in other groups, being true not only of the
mayflies but also, in general, according to H* 2* Wallace of the Lycosid
spiders, according to C* £* dyers of tne dragonflies, aoeording to J* S*
Rogers of the crareflies, and according to I* H* aubbeil of tne Grthoptera.
This unique behavior appears to be linked with the temperature factor* It
has been shown that in the case of the mayflies the odder the water inhabited
by the immatures, the shorter the period of emergence dnce, in Florida,
the lowest winter temperature of the water is probably equal to, or slightly
l^Low, that of the nortnem waters during the summer period of emergence,
mayflies in Florida are seldom,or never, confronted with conditions which -
are unfavorable for transformation* For this reason a species (Paralepto-
phlebia volitans for example) which in Canada emerges only for about two
weeks during the summer, can emerge throughout the year in Florida* The
generalisation that species of northern origin are non-seasonal in Florida,
and that seasonal forms in this state are all of southern origin, holds good;
but this is not a complete statement of the facts* Most of the species be
lieved to be southern in origin are non-seasonal like the northern fonts

41
in this area But this too may be explained on the basis of temperature,
if these southern forms arose in the cold -waters of the southern Appalachians
or the hilly regions of the Piedmont. The only truly seasonal species
are Oreianthus sp# lio# 1, Baetisoa rogersi, Camp sums incertus# Iexagenia
vreem and probably the other species of Hexagenia, Ephemera simulans. Ephem-
ore 11a trilineata, and perhaps a few others#
ZOOGEOGRAPHY
The topography of Florida has recently been described by Cooke (1939)
in his "Soenery of Florida." He divides the state into five natural areas
(see map 1) and these have been found to be olosely correlated with differ
ences in mayfly fauna* A discussion of the divisions of Florida can be
found under the section on ecology#
Since mayflies are so limited ecologically# introduction into a new
area is subject to many obstacles# The many factors influencing drainage
are the dominant elements directing the movement of primarily aquatic in
sects# It has recently been suggested (Hubbell and Stubbs in Carr, 1940)
that i
1* An area in central Florida has persisted, in the form of large
islands or a group of keys, at least since the beginning of the
Pleistocene# and probably since Fliooene times*
2* The bridging of the gap to the mainland on one or more occasions
(perhaps first in the Pliocene), followed by renewed insular iso
lation*
3* Final establishment of peninsular conditions during the Pleistocene*
More or less extensive marginal submergences in late Pleistocene,
4

42
reducing much of the eastern margin of the peninsula to a coastal
archipelago.
5* Persistence of a salt-water barrier between florida and the best
Indies at least since pre-Cenozoic times, and certainly through
out the t>eriod of derivation of the modern biota of the state#
It is unnecessary to hypothesize or theorize that such islands have
existed in order to derive the ephemorid fauna* The winged stage of mayflies
and the methods of dissemination of the insocts would allow for rapid pene
tration of an area should ecological conditions become satisfactory for
the raalntenance of that species* On many of the hahaman islands, conditions
would not allow a very extensive development of mayflies because there
are relatively few or no streams* It is net at all unlikely tuat when
Florida m.3 rising from the sea as isolated islands these islands were
very similar to the Bahamas of today. If such conditions persisted until
land connections were formed, the introduction of mayflies into the region
has been very recent, and, as is hypothesized below, the fauna was derived
mainly through the larger river drainages* Quite lilcBly, there were sane
nayflios inhabiting the Florida islands, but they must have been pond fonos
and species which could withstand wide variations in ecological conditions.
Those species which may be endemic to Florida could oasly have arisen since
the establishment of the peninsula in the Pleistocene*
As Florida rose, the streams draining the southeastern portion of the
continent were extended onto this now area carrying with them their northern
faunae. In the western part of Florida, the Chattahoochee, which drains
the foothills of the Appalachians, and the Flint, which drains the Piedmont
of Georgia, came together to fora the new Apalachicola river* As the

43
Florida tributaries of this great stream began to erode back into the up
lands, the conditions in their valleys tended to approach those of the
more northern reaches of the river, and, as conditions in these tributaries
became suitable, the mountain and piedmont species came to occupy all avail
able habitats within the small, rather rpaidly flowing but sand-bottom
streams.
The Apalachicola river drainage has without doubt been the main high
way of ingress to Florida for the great majority of animals which require
flowing water or hardwood forests, Rogers (1933) found that the ecological
conditions existing in the Apalachicola drainage would admirably explain
the distribution of many northern craneflies in Florida, Carr (1940) re
ports that the most extensive invasion of Florida by the northern element
is encountered in that portion of the panhandle which is drained by the
Apalaohicola river, Hbbell (1936* 354) states that "in this peouliar en
vironment [the deep ravines of the Apalachicola region] a great many northern
plants occur, evidently the remnants of a northern flora left as relicts
from Pleistooene times in these deep, moist, cool ravines ,,," It has
also been noted that many northern plqnts raob their southernmost limits
in these ravines and that many typically southern plants intermingle here
with the northern species. Not only is this true of plantb, but such has
proven to be the case in the craneflies, the Odonata, the Opilionids, the
Grthoptera, the crayfish, the amphibians,and the reptiles.
Many of the species of Florida mayflies which have entered the state
have spread out from the Apalaohicola drainage and now occupy rather wide
ranges in Florida, but there are certain forms which seem to be more or
less confined to this region.

44
Not only has the Apalachicola served as an entry for the ephemerid
fauna, but also the Suwannee and its tributaries may have brought in cer
tain elements fresa the north such as Braohyoerous. Very likely, in addi
tion, there lias been some migration along the more easterly Coastal Plain
region -where the streams descend from the higher Piedmont. However, the
forms which may have entered Florida over these or abhor routes are few in
comparison with those that have come in by way of the western path. Per
haps some species have entered by more than one route, moving in from the
east and from the west and meeting to form a unified population in northern
Florida.
Travers recent paper on the Ephemeropteran fauna of Puerto Rico and
infrequent records of other species from the West Indies show that those
speoies of mayflies found in Florida have but few affinities with the insular
fauna. No species are shared in common, and the genera which occur in both
regions are very widely distributed. Although other species of insects
have become established both in Florida and the West Indies, the mayflies
have been unable to do this principally because of the ecological conditions
of south Florida. The great majority of forms described from the islands
are inhabitants of streams, particularly of mountain streams, and even if
these mayflies were accidentally introduced into Florida, establishment
would be impossible in the south. If,by some rare ohanoe,a female which had
been fertilized were carried to one of the permanently flowing sand bottom
streams, it is barely possible that the speoies might gain a foothold, but
this has apparently not occurred* The only Florida speoies that might be
supposed to have been derived from the West Indian fauna are Callibaetis
floridanus and Caenis diminuta, but the former shows affinities with continen-

tal forms and the latter speoies is also probably of northern origin*
Hobbs (1940) has hypothesized that the crayfish now occurring in
Florida have been derived from migrants from the north or from the west}
his evidence indicates that the western element is much the larger* A few
of the nortnern species of mayflies do appear to have swung westward around
the southern Appalachians and thence into the Gulf Coastal Plain and Florida*
In this sense only* can any part of the Floridian fauna be considered of
western origin*
Among the factors that may be used in explaining the present distribu
tion of rheotropic mayflies in Florida, temperature may have exercised a
considerable influence* In west-oentral peninsular Florida that is,
in the Tampa region the mean annual temperature of the air is 60 degrees
F1-, while in the northwestern part of the state, where the principal part
of the continental fauna is oonoentrated, the average temperature is nearly
ten degrees lower* Since temperatures in streams are less subjeot to varia
tions than those in air, it is likely that average annual temperatures are
more important to aquatic organisms than to terrestrial forms, for which the
extremes of temperature are more likely to be the critical factors* It
seems reasonable to suppose that the score or so of mayfly species common
to peninsular Florida and the western part of the state must have relatively
wide limits of temperature toleration* Those speoies having more restricted
temperature toleration have remained confined to the northern and northwestern
parts of the state*
Dispersal of mayflies
The two most important factors involved in the dissemination of may-

43
flies are wind and water* Of these, the latter, as far as the actual
establishment of species is concerned, is by far the more important, for
the immature stages of all Ephemeraptera (except a very few brackish water
species) require fresh water*
The ability to fly allows for the greatest amount of movement of
ephemerid species, although the adults are more or less oonfined to moist
situations* The relatively short life span of the imagos must necessarily
limit the flight range of the insects; however, the area ocoupied by a
species can be extended somewhat through voluntary flight of the adults*
Such small, feeble inseots as mayfly imagos are easily carried by the
wind* This can be seen in the present distribution of the moire diminutive
genera, Caenis, Baetis, and others, whioh are found throughout the world*
Dr* P* A* Glick, of the D* S* Bureau of Entomology, has made a thorough
and very interesting study of the distribution of insects, spiders, and
mites in the air* By means of traps suspended from the wings of an airplane,
he collected many thousands of insects from various strata of the air* His
results as far as the Ephemeroptera are concerned are listed below:
Caenis
Caenis sp*
Hexagenia
Ephemera
Undetermined
sp*
hiiaris
sp.
sp*
Over 5000
ft*, day
5000 ft.,day
night
4000 ft*,day
night
3000 ft*,day
night
1
2000 ft*,day
1
1
- ... ^Sht
1000 ft*,day
1
night
2
500 ft*, day
night
2

47
Caenis
hi laris
Caenis
sp*
Hexagenia
sp*
Ephemera
sp*
Undetermined
sp*
400 ft*,day
200 ft*,day
1
1
50 ft*, day
The above figures illustrate the fact that mayflies can be carried to
extreme heights, and, by means of horizontal air currents, doubtless to
considerable distances* Perhaps the greatest obstacles to be surmounted in
aerial distribution at great heights are the short adult life and the
necessity for the fertilized female to reaoh fresh water* Even when these
two obstacles are overcome, the chance of the oological factors being satis
factory are but slight; current-loving species could hardly develop in a
pond, and vice versa* The possiblility of distribution through wind currents
at great heights, therefore, seems to be somewhat remote, but the chance
nevertheless exists and must be considered*
From his study, Click concluded that size, weight, and bouyancy of an
insect bear direotly upon the height to which it may be carried by air
currents. He found that many species represented at high altitudes were
small insects* Temperature was undoubtedly the most important factor re
gulating the numbers of insects to be found in the air at any given time,
and he found that the optimum range was from 75 degrees to 79 degrees F*,
surface temperature*
Lr* Click points out that the intensity of air currents is a great
factor in the distribution and dispersal of inseots* most insects were
taken at the lower altitudes when the eurfaoe wind velocity was from five
to six miles per hour, and fewest when it was calm.
Viands at low altitudes are probably of importance in transporting
adult inseots from one region to another but their effedts are probably

48
local; however, such local spreading continued over a long period would
eventually greatly increase the range of a species. A combination of strong
winds at low altitudes, flight, and proper ecological situations -would
allow rapid distribution of mayflies*
Within the continental area as a whole, stream piracy porbably has
acted, and is acting, as one of the principal agents for the dispersal of
mayflies* By this means, speoies may spread from one drainage system to
another and from one region to another, gradually coming to occupy very
wide ranges* This would be particularly important in the case of those
species which as adults have but limited powers of flight and those whioh are
relatively unable to withstand dessioation*
Flood conditions also operate as an influence in the spread of a
species during the immature stages* At the times of flood, stream velocity
is greatly increased, and due to this increase rocks, logs, pebbles, and
other objects to which the immatures cling are moved violently downstream.
Doubtlessly, the greater portion of the animals on these objects are des
troyed, but a few may survive to carry the species far from its original
home. Fran the lower reaches of the stream to which the nymphs have been
carried, the speoies may extend its range into new drainages by the flight
of the winged stages*
It is barely possible that wading birds might play a part in transporting
mayfly nymphs from one body of water to another* Many water dwelling
organisms have been transported successfully on the legs of such birds and
if the flights of the birds were short, necessitating only little time
out of the water, it is possible that certain mayfly nymphs might survive
a journey of this nature*

49
vihen the various possible distributional agencies are subjected to
analysis, it can be seen that mayflies are principally disseminated by
means of flight, by winds near the earth*s surface, by floods, and rarely
by high air currents and stream piracy*
CLIMATIC DIVISIONS OF FLORIDA
C. H* Merriam divided Florida into two regions which appear to be
useful in a general way for differentiating, ecologically, the flora and
fauna of the Nearctic and Neotropical regions* He considered that part of
Florida north of the St. Luoie inlet on the east coast to Fort Myers on
the west coast to be continuous with the Austral zone of the continental
portion of North America, while the remainder of the state lying below
\
this line was Neotropical*
P* P* Calvert, likewise, has differentiated two zones in Florida, separ
ated by differences in the mean annual temperature* Most of peninsular
Florida falls into his Zone III,which has a mean annual temperature ranging
from 68 degrees to 77 degrees F*, while the western region is in his Zone
II,with a temperature ranging from 59 degrees to 68 degrees F*
Rainfall in the Nearctic region of Florida is to seme extent confined
to a mid-summer rainy season, which in the southern tip of the state becomes
more distinct. In the northwestern area, although there is same demarcation
of a rainy season, the rairfall is more evenly distributed throughout the
year* Byers (1930) has given in tabular form the average rainfall and tempera
ture in various regions of the state in July and January, and this shows
fairly well the tendencies described above*
The distribution of mayflies in Florida is, for the most part, dependent
on the presenoe of running water, although temperature probably also exeroises

Fig* 1* Normal annual temperature and precipitation, as compiled
from all available records to 1917 inclusive* Lines with numbers
and the degree mark () at the end indioate temperature; shaded
portions indicate inches of preoipitation during the year*
(From "The Climate of Florida" by Mitchell and Ensign)

bl
no little influence, ¡since great areas of the state are characterized by
swamp-like and sandy conditions and pine barrens with no development of
streams, their Epheraeropteran fauna is extremely limited. This is par
ticularly true of that portion which lies at the southern tip of the state
*
and commonly designated the Neotropical region. The mayflies found here
are not Neotropical in origin, but are true Hearctic species distributed
throughout Florida; in fact, Caenis diminuta is just as common throughout
the eastern part of much of the Hearctic as in this unique, southern,
biological area*
THE HABITATS OF FLORIDA MAYFLIES
It is generally recognized that the mayfly population of a region
is intimately related to the aquatic conditions of that region. From the
standpoints of both the ecological distribution of mayflies and physiography,
Florida can be divided into five natural areas (see map 1). The boundaries
of these areas shown on the map are rather arbitrary. The aquatic con
ditions in the ooastal lowlands overlap to a great extent those conditions
found in the other areas, but these boundaries are useful in delimiting
in a broad way the iresh water situations as they occur in Florida.
The ooastal lowlands almost everywhere lies less than one hundred feet
above sea level; the height above sea level of the other regions varies
from one hundred to about three hundred feet. The drainage of these various
subdivisions of the state is closely linked with the topography.
The ooastal lowlands is a swampy and marshy area,including, in its
southern roaches, the great expanse of the Florida Everglades, and con-

>
tinuing northward into th mucklands of th Lake Okeechobee region, which
in burn is continuous northwards on the oast and west with the lowlands
of the coast*
The central highlands may be divided into two areas* The southern
half is entirely a lake region where almost every depression has its own
pond or lake; the northern part of this division not only includes lakes
ponds, but there are also numerous surface as well as subterranean streams
of all sises*
The Tallahassee hills and western highlands are rolling areas composed
of red-clay hills, well drained by many small streams* The Marianna low
lands, on the other hand, is made up for the most part of flatwoods, swampy
areas, and rolling sandy hills oovered by pine forests with few permanently
flowing streams*
Several large rivers arising in Alabama dnd Georgia flow through north
western Florida and empty into the Gulf of Mexico* In the east, the large
St* Johns river flows north along the border of the central highlands and
the coastal lowlands*
DESCRIPTIONS OF M3ITATS
Streams
Intermittent Creeks
In Florida, there are relatively few intermittent streams* These few
are, for the most part, merely connecting canals between swamps, ponds
or other bodies of water the level of which fluctuates continually according
to the amount of precipitation* As far as mayflies are concerned, they
are rather poor situations, and only the very tolerant Callibaetis and

Caers nymphs can withstand the alternating conditions in the creeks pro
duced by the continual changes in level of the bodies of water connected
by the intermittent streams* Vegetation is usually abundant, but it is
not of the type found in constantly flowing waters* Also, the drying of
parts of the canal bed produces conditions which the stream inhabiting
mayfly nymphs cannot for long endure, and even if, by chance, a species
should become established during the period of flew, the cessation of this
flow would bring about the death of the immatures*
Permanent Creeks
Permanently flowing streams are the most important of the mayfly
habitats in Florida* The oreeks of this area may be divided arbitrarily
into the following categoriess
(1) Sand-bottom creeks with little vegetation*
(2) Sand-bottom oreeks choked with vegetation
(3) Silt-bottom creeks wrch little vegetation*
(4) Silt-bottom creeks choired with vegetation*
(1) Sand-bottom oreeks with little vegetation: These are small, shallow,
gently flowing streams with sandy beds* The oreeks vary from as little as
one foot to forty feet in width, and in depth from a couple of inches to
as much as five feet. The bottom is composed of loose, rolling sand which
builds up, in mid-stream, into small ridges behind which small masses of
debris accumulate* Large rocks almost never occur in Florida streams, but
pebbles may be found imbedded in gravelly riffles where the water becomes
quite siiallow. There are occasional pools, but they are not a conspicuous
element of the streams* The pools are usually small, quiet areas near the

64
banks or at curves* debris accumulates to a rather marked degree in some
of the streams, almost any obstacle forming a nucleus for tne accumulation
of much leaf drift, sticks, etc* Tree brunks frequently form dams and give
rise to riffles, while the tangle of branches and twigs provides a network
in which, much detritus becomes entangled tilt accumulates near the shore
and in places may produce rather thick deposits, in some streams even forming
a layer more than two feet in thickness; however, for the most part, the
silt deposits in the sand-bottom streams are sparse and of little consequence*
Near shore, leaf drift becomes a fairly important habitat, for many insects
are harbored in this material, and in the almost stagnant shore pools the
leaf debris may be several layers thick, interspersed with silt* The flow
of water in the sand-bottom streams is never rapid in the sense in which
a nortliern stream is said to be rapid; rather, the flow is gentle with the
surface seldom breaking* Most of these streams are oiroum-neutral to slight
ly acid, butt some may be pronouncedly acidic* Nearly all of them have
tinted waters which vary in shades from almost colorless to a strong tea
color according to the area drained and to the amount of rainfall* Most
of the streams drain flatwoods, hammock lands, or swampy areas, and are
fed by springs or diffuse seepage areas. Vegetation is almost completely
absent from the streams except for a few scattered Orontium plants and an
occasional dump of her si caria near the quiet shore zone; however, these
plants are not particularly important from the standpoint of furnishing
habitats for mayflies*
(2) band-bottom creeks choked with vegetation: This sort of stream occurs
mostly in the northwestern part of Florida beyond the Apalachicola river.
The beds of the creeks are composed of fairly loose sarad, but instead of

65
bein' almost bare, as in the type of stream mentioned above they are
covered with dense growths of Vallisneria, Sagittaria, and Potamogetn
and these plants in turn are thickly covered with algae There may be some
debris collected in the sloxver areas near shore, but in mid-stream the vege
tation is swept quite clean, although an occasional partially submerged log
may lie among the plants. These streams are usually not much more nor
less than twenty feet across and may be as much as five feet in depth at
the odnter. In their deeper parts, the vegetation tends to disappear, and
may be entirely absent from exceptionally deep stretches. The rete of flow
is moderate, but seldom strong enough to cause any marked disturbance of
the water surface. For the most part, the creeks drain scrub lands and
high pine and hammook country, and the water is much lighter in color
than that of the streams described under (1); however, the water is usually
definitely acidic, with a pH approximating 6,0. Silt deposits are not as
pronounced in these streams as in those of class (1), and debris along the
shore is likewise less in quantity,
(3) Silt-bottom creeks with little vegetations Silt-bottom streams are
rather common in the northern part of the central highlands of Florida*
The stream bottom is covered with a layer of silt overlying the sand and
varying from a few inches to several feet in depth. The rate of flow is
comparatively slower than that of the sand-bottom streams, but is is
steady and quite perceptible. The water is definitely acidic and usually
rather strongly tinted, often approaching a strong coffee color. The silt
bottom is frequently overlain by layers of leaves and strewn with much
ether debris, but there are few cr no plants in the stream proper. Near
shore Persicaria and various sedges and grasses may be present, but they

56
are not especially abundant# This type of creek averages about twerty
feet in width and from a few inches to three feet in depth.
(4) Silt-bottom creeks choked with vegetation: These streams are not
i mmamw6^#.
particularly common in Florida, and are confined mostly to the northwestern
part of the state# The streams are shallow, one to three feet in depth*
bub they may bo quite wide and very meandering in their courses, and are
sometimes braided. The vegetation is quite dense, and may include plants
which are characteristic of more slowly flowing or even stagnant water,
such as Isnardia, Persioaria, and Pontederia. Other plants also found
in the course of the stream include Vallisneria, Potamogetn, and Saglttarla
as well as many algae. The silt in the streams is very loose and maybe
as much as tliree to four feet in thickness# This material is soft, fluffy
and somewhat sticky, and at the slightest disturbance stirs up and clouds
the water# There is usually a broad flood plain, and dur'ng igh water the
streams spread out widely over it until all vegetation is completely sub
merged (except larger bushes and trees). There is a constant flux of channels
due to this flooding. In the shallower sones, the rate of flow of the water
is negligible and during a rather severe cold spell, I noticed that the
surface of one of the streams was frozen over in the shallow zones.
Rivers
(1) ot a grant r ive r s: htagn&rsfc rivers are, for the most part, confined to
the southern portion of the Floridian peninsula, and many of them have
been dredged within the last few years to serve as drainage oanals for the
Uverglades. These rivers are not, strictly speaking, stagnant but the flow
is so slight that only those rheotropio organisms which are very tolerant

57
to stagnation can exist in these waters, ihe Miami river furnishes an
ideal example of such a waterway. Until the drainage plans were carried
out the Miami river was, in places, a shallow, moderate to swiftly flooring
stream cutting through the limestone which. forms the bedrock for south
Florida. Charles £ Cory in nis book "hunting and. Fishing in Florida" des
cribes and illustrates the Miami river as it vas in 1895, and paints a
picture which certainly differs enormously from the present states "The
Miami river, which runs from the Everglades into Biscayne Bay, is probably
the cn~y river in Florida which has a fall or rapid worthy of the name*
For about a half a mile at the head of this stream there is considerable
fall* At this point the river is shallow and not navigable for boats,
and has a very rapid current, in which CavaHa* (Caroux hippus) are
numerous and may be taken with an artificial fly." Dredging has completely
eliminated all rapids from the river and flow is not perceptible, even during
the rainy season. The salt water of Biscayne flay backs up into tne river
and produce a brackish condition some distance from the mouth of the canal.
These stagnant rivers have fairly heavy growths of aquatic vegetation
near their 3nores, but they become deep rapidly and in the deep regions the
plants are quite limited. The rivers vary from one hundred to two hundred
foot in width in the widest places, and in depth usually range from fifteen
to twenty feet* borne of the rivers do show a pronounced flow during the
rainy season and may even be subject to floods, but since the digging of
tae drainage canals, tnis is the exception rather than tiie rule. There is
very little deposit of silt in these streams axid the bottom is mostly bare
limestone.
(2) Slowly-flowing,deep riverst This category includes nearly all of the

53
larger rivera of Florida such as tas Suwannee and the Apalachicola* These
streams are large and deep, and drain very extensive areasj the Suwannee
drains the Gkefenokee Swamp and the Apalachicola arises in the foothills
of the Appalachians and the Piedmont of Georgia and Alabama* The larger
rivers have continuous flow, and during oxeesgive rains they spread cut
over their flood plains* In those largo rivers, vegetation is limited and
occurs principally near the shores in protected places where the current
is slow* This vegetation is more characteristic of standing water than of
streams* There may be some rocks near shore in the shallow water, and
silt may be deposited in protected areas, but for the most part the bottoms
are hare clay or limo rook. The Apalachicola river is frequently very muddy
due to the heavy burden of silt it brings down from the Georgian highlands*
The btrarcui: ee is muohP'Slearer, although the water may bo strongly colored
by the various organic acids ooming from the swamps drained by the river*
The Jt John's river has a much slower current than the other two streams
just named, and north of Lake George the flow is slight and affected by the
tides. This river has masses of water hyacinths growing at the shore, and
conditions are not very different from those found in the lakes of the
central highlands which support growths of this plant* Hearer its head
waters, there is Vallisneria and Sagittaria in the stream and the flow is
more noticeable. Much of the water of the St* Johns is of swamp origin,
and this is reflected in the brownish coloration of the stream*
(2) Larger calcareous streams; This category includes streams which are,
in general, smaller than those included above and which arc definitely basic
in their reactions* Most of these streams arise from springs and form
small rivers such as Silver river, Wakulla river, the Santa Fe river, etc*

59
They are clear, cool, and moderately flowing with rather dense growths of
vegetation in the stream proper. Vegetation is composed ohiefly of
Vallisneria, Sagittaria, Nais, Isnardia, mosses, many algae, eto. which
in the shallower zones form dense mats completely covering the floor of the
stream. The water may be oolorless if the source is confined to springs,
but if swamp waters also contribute to the stream the water may be tinged
with brown* Many of these rivers have sand-bottoms, and there may be thick
deposits of silt in the quieter shallow zones. Leaf drift and other debris
becomes entangled in fallen trees and other catch-alls, and such debris
forms an important habitat for many mayflies and other organisms. In some
of the rivers, there are outcrops of limestone, and in the Santa Fe river,
specifically, there are many loose rocks which are of great importance as
habitats for aquatic organisms. The depth of these streams varies from
three feet to twenty feet or more, the width from seventy-five to three
hundred feet, Faunistically, this type of stream is the richest found
within the boundaries of Florida, both in number of individuals and in
species. Carr (1940 25) states that Optimum conditions [for fluvial
organisms] apparently exist in those rivers which run over ledges of ex
posed limestone, or which receive most of their water from calcareous springs.
Ditches and Puddles
(l) Roadside ditches: These are extremely rich situations for aquatio
organisms if there is permanently standing water in them. The ditches
are quite varied in appearance but the fauna is fairly constant. In some
of them, there are dense growthB of Pontederia which is the predominant
plant. The water is shallow in the zone of pickrel weed, but may become

so
much deeper beyond this region; in the deeper parts other vegetation
which can stand greater degrees of submergence is present* The bottom
of the ditches is usually covered with grasses and may have heavy growths
of Globifera umbrosa, Isnardia, and Persicaria* Algae form dense mats
in some of the ditches along with Ubrioularla, Geratophyllum, Potamogetn,
and Myriophyllum. At times the water may become very warm, in fact hot,
during the summer; in winter it is often quite oold, with ice sometimes
forming over the surface* The water in these ditches is usually acid but
may be basic; the lowest pH recorded was slightly above 4*0. The depth
of the water varies from a few inches to as much as four or five feet, and
the width of the ditch (that part containing the water) may be from one
to fifteen or more feet*
(2) Puddles In this category are placed those small and transitory bodies
of water left by the retreat of a stream or formed by heavy rains* There
is no, or very little, aquatic vegetation in such puddles, and it is
only by remote chance that organisms are found in them* Such animals are
stream relicts which soon perish, for the puddles dry up rapidly during
dry weather; however, I have found mayflies in such places and for that
reason I am including this situation* In some of the puddles there may be
several layers of leaf debris. Silt accunulates between the leaves and
algae begin to grow, continuing as long as the water remains*
Ponds
The ponds of Florida may be divided into several types, but nearly all
of them share one characteristic in common they seldom have streams
draining into or from them*

61
(1) Sink-hole ponds; These ponds are formed by the dissolution of under
lying limestone. Rainwater, percolating downward to the water table, dis
solves vertical chimneys in the limerock into which the surface cover may
l\
collapse gradually or suddenly, producing a steep-walled, open sink. Where
the oover is thicker or less oompact a saucer-shaped or funnel-shaped depres
sion may result. There are many of these ponds of sink-hole origin in
Florida, and in particular around the Gainesville area. Some of them are
dry but the great majority have standing water, which maintains a fairly
constant level because the water table is high enough to supply the ponds
continually. The sides of the ponds both above and below the water level
are steep and the zone of rooted aquatic vegetation is very limited. The
sides of the sink-holes above the water are usually covered with vegetation
which extends from the edge of the water up to the rim of the depression*
In many of the sink holes a narrow sand beaoh may be fomed where the slope
of the sides levels off, but the shore zone exfcendint into the water from
this beaoh is very narrow, and the drop to deep water rapid. There are
two ohief types of sink-hole ponds*
(a) Ponds with the surface free of vegetation* This is one of the
common types of sink-hole ponds encountered in peninsular Florida.
The margin of the pond has a fairly rioh growth of both submergent and
emergent vegetation, which extends outward to the region where the drop
off occurs. This is oomposed principally of Saocrolepis striata, Per-
Be paria, Mayaoa fluvitalis, Juneus, and some Typha as well as numerous
species of algae. This sudden drop to deeper water begins at a depth
of about four and extends to a depth of about ten feetj thence the drop
continues more gradually to about twenty feet. In many of the ponds

62
there may be deeper holes such as that found in Late Mize, discussed
by Harineas (1941), which over a very small area reaches a depth of
nearly eighty feet. In the shallower portions the bottom is sandy and
covered with patchy growths of Utrloularia. There are only small deposits
of silt in the shallower zones, but in the very deepest parts the bottom
may be thickly covered with black, dense silt, in which practically
anaerobic conditions exist and in which living organisms are almost
entirely absent* The water varies from odorless to a strong tea color,
depending on the type of region drained by the pond* Many of the ponds
are rather turbid, and this turbidity combined with strongly tinged
water allows little penetration of light to the deeper parts. The water
varies in reaction from pond to pond, being acidic, circumneutral, or
slightly basio*
(b) Sink-hole ponds with the surface covered with vegetation: There
are two principal varieties of this pond type (l) those covered with
water hyacinths (fiaropus crassipes); (2) those covered with duckweed
(Lemna minor), mud-marys (Bruneria punctata), Azolla carolinlana,
Salvinia aurloulata, etc*
The first variety of pond may have a marginal ring of open water
with t he water hyacinths concentrated over most of the remaining area,
or the entire surface may be covered with these plants* If there is some
open water, submergent vegetation may take root and beoame fairly well
established, but for the most part the water hyacinths are the only
plants of any importance in the ponds* The duckweed covered ponds
seldom have any submergent vegetation growing in them, for the entire
surface is oovered with a single layer of these plants outting o^f

S3
light from any vegetation which might attempt growth on the pond bottom,
when there is any wind the duok weed piles up and leaves clear areas
on the water surface, but as soon as the wind dies down, the plants
again spread evenly over the surface. Amphipods (liyallela azteca)
are exceedingly numerous in these pends living among the duckweed, but
bottom organisms are scarce probably because of the small amount of
oxygen. The bottom of this type of pond has rather thick accuaulat ions
of black silt, heavily loaded v.-tth hydrogen sulphide, covering the
sandy bottom, and almost anaerobic conditions exist there* The sink
hole ponds are usually about one hundred to three hundred feet in
diameter, and are mostly round in shape. Some of the larger ponds
are formed by the coalition of two or more sink-holes.
(2) Fluctuating pondsi These constitute one of the more frequently encount
ered types of Florida ponds. Water fills shallow basins some mere
depressions in the original sea-laid sands, the majority produced by solu
tion of underlying limestone or by wind action. The level of the water in
these hollows varies with the amount of rain and surface runoff. There is
a great fluctuation in the area occupied by the water beoause a slight
rise or fall causes marked spread or retreat of the margins, but the depth
usually does not change greatly because of the shallowness of the pond. True
aquatic vegetation follows the rise and fall of the water to some extent,
but it is chiefly confined to the region below the more permanent water level.
"These periodic and sporadic fluctuations [due to the rainfall] prevent the
development of any permanent vegetation within the broad zone of fluctuation*
As the water recedes in the dry season, it leaves a belt of saturated earth
in which some grasses and sedges spring up among mats of stranded algae and

64
other aquatic vegetation .... The permanent water is usually filled with
submerged, floating, and emergent aquatic plants and may support extensive
floating mats of green algae." (Sogers, 1933)* The vegetation includes
many true aqu&tios such as Pontederia, Utricularia, Persicaria, Slobifera,
lypha, eto. as well as Hydrocotyl, maiden-oana (Juncus), and other semi-
aquatios. Many of the ponds have coverings of Castalia, and seme support
Nymphaea, bub very few are covered with water hyaointhe* Plants are not
confined to a shore zone, as in the sink-hole ponds, but may extend much
further out and in some instances may completely penetrate the ponds.
The bottom of the fluctuating pond6 is mucisy, but the layer of silt is not
deep* The water is subject to rapid changes in temperature and is much
influenced by external weather conditions. There is normally a slight tint
to the water and it is usually acidic.
(5) Temporary woods pondst These ponds are foxmed in depressions in ham
mocks and are of a more or less temporary nature; however, the vegetation
present is such as to indicate its habitual occupation of the depression*
In these ponds and around their margins are frequently found black-gum
(ifyasa biflora), button bush (Cophalanthus occidentalis), willow (Salix
ni ;er), bladderworts (Utricularia sp*), etc*, and if the water remains
for a sufficient length of time other more succulent vegetation will beoome
established* niter the water has been standing in the depression long
enough to allow growths of algae, many of the usual pond animals begin to
migrate to and become established in the pond*
(4) Sporadic ponds: The sporadic ponds are of a rather temporary nature,
and during the dry seasons may completely disappear not to reappear for
some time, perhaps they may even disappear permanently* If they remain for

35
a time, vegetation and animals may become established, but frequently they
dry up in such a short period that such does not take place* The ponds
are shallow and may be large or small depending on the depression and the
drainage of the region*
(5) Jerome sinks Because of the unusualness of this situation, it deserves
special classification* A descriplton of the sink is included in the dis
cussion of the ecology of Choroterpes hubbelli on page V6 *
Lakes
According to the recent investigations of Mr* S. Stubbs of the Florida
State Geological survey, nearly all lakes in Florida are the result of
solution of underlying limestone} however* suoh lakes as Late Okeechobee
seem rather to occupy basins which are natural depressions in the surface
formed as the land rose during the last geologic period. "Many Florida
lake basins are simple sinks that have always been tributary to the ground-
water supply and never have had a surface outlet. Others at one time or
another formed part of the surface drainage and. therefore were connected
with the river system. Their history is complicated, for the fluctuations
of sea level and the consequent fall or rise of the water table gave
opportunity alternately to deepen the basin or to flood them. Some of them
appear to have been estuaries during higher stages of the sea, for the
sand-covered terraces around them stand within the limits of altitude of the
coastal terraoes*" (Coote, 1939: 100-101). Cooke concludes that Late
Okeechobee, Late Istokpoga* Late Xissiranee, Crescent Late, Late George,
and others originated as hollows in the sea bottom*
(1) Sand-bottom latea By far the commonest type of late found in Florida,

es
the sand-bottom lakes form the most conspicuous bodies of water in the
central highlands. There are literally thousands of these lakes in this
region and they are particularly numerous in Late oounty. The lates vary
in size from a quarter of a mile to nine or ten miles in width, but the
depth is not correspondingly great and most of them are sliallow, not more
than forty or forty-five feet at their deepest holes. There is little
vegetation except at the margin, and this is chiefly Saocrolepis striata,
Utrioularia, and algae. Wave action is slight but it is probably suffi
cient to prevent the growth of more usual aquatic vegetation along the
sandy shore. The dacorolepis extends out into the lates to a depth of five
or six feet and beyond this zone vegetation is limited to submergent plants
such as Utrioularia, which lies on the sand bottom as far out as there is
sufficient light penetration for normal photosynthetio processes to take
place* In this region, some silt is intermingled with the sand, but much
of the sand is bare, beyond a depth of about twenty feet, silt accumulates
and covers the bottom sand with a layer several inches deep; with increase
in the depth of the lake there is a direct increase in the amount of silt.
In the very deep parts of the lakes, the silt may reach a depth of a foot
or more, and in this region it is a very thick, black, fine, and oozy mud
in which almost no organisms live# Along the shore some debris colleots,
but is not abundant; this debris forms an habitat for many insects which
are normally found in streams. Probably the wave action in this region is
sufficient to oxygenate the water and produce conditions whioh simulate
those of moderately flowing streams. The water of the lates varies from
very clear to strongly tea colored and the turbidity is also very variable
according to the late. Most of the lates are oircum-neutral, ranging not

67
much more than *5 on either side of a pH of 7.0*
(2) Silt-bottom lakes This type of lake is well exemplified by Lake
Newnan near Gainesville. The lake is quite large, being about ten miles
in length and about three miles wide. It is bordered by a ring of eypress
which extends from dry land into the water. Also margining the lake, water
hyacinths form dense growths between the bases of the cypress trees and
extend out into the lake as far as there is a protected zone. V/ith every
shift in the direction of the wind, water hyacinth plants break free and
float across the lake, pushed onward by the wind. Frequently, during a
period of sustained moderate winds, the lake is dotted with numerous floating
"rafts of water hyacinths; eventually these plants pile up along one
shore until the wind again changes and sends them sailing back to the opposite
3ide. The continual rain of dead water hyacinths onto the bottom of the
lake has given rise to a thick layer of loose fluffy silt which completely
covers the bottom to a depth of two or more feet* almost no living organ
isms can be found in these bottom deposits for conditions are not conducive
to life. The lake is shallow; in the middle it is not much more than ten
feet in depth, and over most of its area it is shallower than this. The
water has a definite brownish tinge and is rat her turbid*
Numerous other lakes in the central highlands also belong in this
same category. Orange lake, one of the larger lakB3 of this region, is
similar to Late Newnan in its type of bottom, bub is is deeper, has much
rooted vegetation in the form of water bonnets, and is somewhat exceptional
in having numerous floating islands of vegetation. Some of these floating
islands are large enough to support trees, but the great majority are small
clumps of vegetation which float about,changing location with each change

68
in direction of trie wind*
These lakes show great variations in their aquatic vegetation; in
many, the succession is directly toward swamp conditions with extensive
development of cypress along the muddy shores; in others there is a distinct
development and sonation of marsh vegetation before the shallow water is
invaded by cypress or hardwood swamps." (Rogers, 193b).
(3) i-isappearing lakes certain large lakes in the northern part of Florida
go dry during periods of drought* Lake lamonia near Tallahassee is an
ideal example of a disappearing lake, and went completely dry in 1938.
There is one near Lake City which is said to go dry periodically, "once
every seven years." These lakes are shallow, and inmost respects are
similar to the silt-bottom lakes in having an abundant growth of water
hyacinths and a ring of cypress bordering them. Although at their maximum
extent the disappearing lakes are fairly large, they vary greatly in size
with seasonal fluctuation in depth*
Marshes
(l) Larshes are very oommon in peninsular Florida, particularly in the
lower regions* They may be very limited in extent or quite large according
to tne size of the origxnal basin, itony ponds and lakes have become con
verted into marshes, and many others are in the process of transition.
The water is shallow and vegetation extends throughout, growing very pro
fusely. The most predominant plants are emergent and include cat tail,
pickrel weed, maiden cane, saw grass, water lillies, 3martweed, and various
grasses* Submergent plants are quite prominent including Isnardia, G-lobi-
fora, Lyriophyllu, and many algae. The water is rather m.m during the

69
summer and may freeze over during prolonged, periods of cold The filling
of lake and pond basins is rapid and the great amount of decaying vegetation
quickly builds up deposits of peat, which finally replaces the water of the
marshes. The level of the water is subject to great fluctuations accord
ing to the amount of' rainfall, and at times the marshes go completely dry,
but over the greater part of the year, water remains in them* The marshes
are definitely acidic, some having a pH ranging below 3*Sj but this con
dition is local, and at different points in the same marsh the pH may range
frcoi 3*6 to 6*0 or higher* The organisms found in the marshes are not
essentially different from those occupying similar habitats in ponds and
along lake margins, for conditions in these marshes are very much like
those of the pond margins* The principal differences lie in the facts that
emergent vegetation occurs throughout the water rather than being confined
to a shore zone, and in shallowness, the marshes being not much more than
three feet deep at their deepest point*
(2) Another type of marsh found in the central part of Florida is very
similar to the above except that vegetation is principally Persicaria and
saw grass (Hariscas jam&icensis), with the fontederia much more limited in
extent and with no Kymphaea present however, the organisms inhabiting
these marshes are identical with those found in the other types.
(3) The Everglades > The Everglades are so distinctive that they require
discussion under a speoial category. "The Everglades occupy a nearly level
plain, which slopes from 1-5 feet above sea level at the south shore of Late
Okeechobee to sea level at the tip of the Peninsula, a distance of more than
one hundred miles. One the west the Everglades merge into the Big Cypress
Swamp, which presumably is a