Title: Species abundance relationships of aquatic insects in monotypic waterhyacinth communities in Florida
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00099130/00001
 Material Information
Title: Species abundance relationships of aquatic insects in monotypic waterhyacinth communities in Florida with special emphasis on factors affecting diversity
Physical Description: x, 166 leaves : graphs ; 28 cm.
Language: English
Creator: Balciunas, Joseph Kestutis, 1946-
Publication Date: 1977
Copyright Date: 1977
Subject: Aquatic insects -- Florida   ( lcsh )
Insects -- Florida   ( lcsh )
Water hyacinth -- Florida   ( lcsh )
Entomology and Nematology thesis Ph. D
Dissertations, Academic -- Entomology and Nematology -- UF
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
Thesis: Thesis--University of Florida.
Bibliography: Bibliography: leaves 152-163.
Statement of Responsibility: by Joseph Kestutis Balciunas.
General Note: Typescript.
General Note: Vita.
 Record Information
Bibliographic ID: UF00099130
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000012411
oclc - 03982982
notis - AAB5202


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Dedicated to my father. Jurgis,

whose support made this possible.


This study would not have been possible without the

contributions from many authorities. I would like to

acknowledge the following for verifying my identifications

of aquatic insect groups for which they are the acknowl-

edged authorities: Dr. Lewis Berner, Dr. Oliver Flint,

Dr. Dale Habeck, Dr. John Hellman, Dr. Jon Herring, Dr.

A. S. Menke, Dr. Paul J. Spangler, Dr. 11inter J. Westfall,,

and Dr. Frank Young. My special thanks to Mlr. William

Beck for identifying all thousand-odd chironomid larvae.

I would like to give special thanks to Drs. Minter J.

Westfall and Archie Carr, during whose courses this project

was conceived, and to my major professor, Dr. Habeck, whose

support and perseverance allowed completion of the study.

I would like to thank Dr. Ramon Littell and Mlr. Walter

Offen of the University of Florida Department of Statistics

for their help w~ith- statistical analyses of my data. I would

also like to thank my former roommate, Mlr. Roger Jones, pres-

ently at the Dartmouth Department of Physics, for his guid-

ance concerning the mathematical portions of this study.

I also acknowledge Florida Collection of Arthropods

andi the Northeast Regional Dat~a Cent-er (NE1RDC) for use of

their facilities and Florida Department of Natural Resources

for Lheir partial support of this study.

Also wish to acknowledge a special debt of gratitude

to L~inda M. Barber for her editing and typing of the manu-

script and for her general support during the analyses and

documentation stages of this project.


ACKN.~OW~EIGLEDGENT . . . . . iii~~ii


LIST OF FIGURES .. . . . .viii

ABSTRACT . . .. . .~~~ ix



Eichhornia cr-assipes (M~artius) Solms-Laubach . . 3

Description .. . . ~ 3
Taxonomy 3
Distribution--Flori~da .. 5
Productivity and Reproduction . . . .. 7
Environmental Requirements . . . .. 8
WJater Quality . . . 10
Economic Importance . . . 12
Habitat for Aquatic Insects . .. . 15

HIETHIODS . .. ... 19

Samnple Site Selection . . . . 19
Collection Methods .. . .. .. . 21
Water Quality . . . . . . 21
Identification . ... . .. 24
Analyses . . . . .. 28


General . . .. 41

Comlments on Species List . . . . 41
Physical and Chemical Variable
In terre lat ions hips . . . 119
Regression Analyses . . . .. 120



Comparison of Study Sites .. .. . 120

Description . .. . . . 120
Species List Comparisons . . .. . .. 123
Estimation of Total Number of Species . .. 128
Factors Affecting the Numnber of Species
and Genera . .. . . 140

Diversity Studies . . . .. . 141

General . . .. . .. . . 141
Dependence on Sample Size . . . . .. 142
Relations to Plant Part Size, Depth~and
Time of Year ... .... 144
Relationships to Water Quality Parameters . 146
Conclusions--Choice of Indices . . . . 147

SUMMIARY ..... ..~~. 150

REFERENCES CITED . .. . . .. 152

APPENDIX A . . . . 164

Fortran program for Sh~annon's and Simpson's
diversity indices (and Brillouin's, whefn possible)

APPENJDIX B . . . 165

Fortran program for rarefaction diversity index

BIOGRAPHICAL SKE~TCH . .. . ... . 166



Table 1. List of collection sites .

Table 2. Annotated list of insects

Ephemeroptera ....
Odonata ...
Htemi-ptera ....
Trichoptera ....
Hlegaloptera ...-
Coleoptera ....
Lepidoptera ....
Diptera .....

Table 3. Ten most abundant insects

Table 4. Ten most frequent insects

Table 5. WJater quality correlation

Table 6. TIen most abundant insects,

Table 7. Ten most frequent insects,

Table 8. Ten most abundant insects,

Table 9. Ten m7ost frequent insects,

Table 10. Ten most abundant insects,

Table 11. Ten most frequent insects,

. . . 20

. . . 42

. 2
. 45
. . 56
. . 67
. . 68
. . 69
. . 101
. 102

. . 117

. . . 117

. . . 121

Camps Canal . . 124

Camps Canal . . 124

Lake Alice . . 125

Lake Alice . . 125

I-75 ditch . - 127

I-75 ditch . . 127

Table 12.

Table 13.

Mean values for diversity indices ....

Order of entry of variables into diversity
models . .. .

. . 143

. .148


Figure 1. Generalized species accumulation curve . .. 34

Figure 2. Preston's species abundance curve . ... 34

Figure 3. Species accumulation curve, Camps Canal .. 130

Figure 4. Species accumulation curve, Lake Alice . 131

Figure 5. Species accumulation curve, I-75 ditch . .. 132

Figure 6. Species abundance curve, Camps Canal . .. 136

Figure 7. Species abundance curve, Lake Alice . . 136

Figure 8. Species abundance curve, I-75 ditch .. .. 137


Abstract of Dissertation Presented to the Graduate Council
of thle University of Florida in Partial Fulfillment of
the Requiremnents for the Degree of Doctor of Philosophy



Joseph Kestutis Balciunas

December 1977

Chairman: Dale H. Habeck
Mlaj or Department: Entomology and Nematology

Collections of aquatic insects beneath mionotypic water-

hyacinth communities, initially standardized by collecting

effort, later based on a standard sampling area, were made at

37 different sites in 18 Florida counties. Identifications,

verified by authorities for respective groups of the 5485

specimens collected, indicated 147 species of aquatic insects

were present. Comparison of this species list with those from

2 other studies more limited in scope indicated several mis-

identifications by previous workers and a much greater range

of aquatic entomofauna. Although the low level or absence

of dissolved oxygen (DO) has been frequently reported, DO-breathing

forms were abundant and frequent in my collections.

The importance of the relative abundances of each species

at the collection sites was demonstrated by discriminant

analysis which showed that the 3 repetitively sampled sites

were significantly different bansed on the abundances of only

the 10 most frequently collected insects. Species abundances

were also used in 2 methods of estimating the total number of

species present at each of the 3 study sites. Statistical fit-

ting of an exponential species accumulation curve revealed

that approximately all species present at each site had been

collected. The fitting of a lognormal distribution curve to

the plot of the species abundance data indicated that approxi-

mately 70% of the total species present at each site had been


Reducing the species abundance distribution for each

collection to a single statistic often helps in elucidating

the effects of plant morphometric, water quality and other

parameters. Diversity indices, especially those which combine

species richness and species evenness, are the most common method

of reducing the species distribution data to one statistic,

and 3 different diversity indices were calculated for all my

collections. All 3 indices indicated an increase in diver-

sity with decreasing values of alkalinity or some parameters

strongly correlated with it. Higher levels of iron in the

water increased the diversity at least for the Camps Canal

study site. However, none of the diversity indices were

able to distinguish between the 3 study sites, indicating a

loss of informlation due to the reduction to a single statis-

tic. TLhe use of diversity indices would thus appear to have

more limitations than might b~e inferred from their popular-

ity in ecological literature.

Although waterhyacinths cover an estimated 200,000 acres

of water in Florida, the aquatic entomofauna beneath them has

scarcely been studied. Some researchers believe that the

water beneath waterbyacinth mats is relatively devoid of life

due to a reduction of dissolved oxygen. Of the two previous

studies of aquatic insects beneath waterhvacinths, one was

restricted to canals in South Florida, the other to a single

reservoir in Central Florida; neither identified the aquatic

insects to species level. By collecting and identifying

aquatic insects beneath waterhyacinth communities at 37 loca-

tions in 18 Florida counties, I hoped to provide a better

picture of the variety and extent of the aquatic life in

this common Florida habital-.

MIany studies of a particular habitat are surveys, re-

porting only the presence of a species. By standardizing my

collecting methods, I hoped to determine if the abundance of

individuals in each species was also important. By taking

measurements of the waterhyacinths and a number of water

quality parameters, I hoped to elucidate the environmental

factors affectinge species composition and abundance. Repeti-

tive sampling of 3 study sites also would allow detection of

seasonal changes in the co~mposition of the aquatic entomofauna


and determination of whether the abundances of different

species could be used to differentiate between the sites.

The utility of species abundances for determining the

estimated number of species present at a sampling site was

demonstrated by 2 different methods. By comparing the re-

sults of the estimated total number of species, as calculated

by fitting an exponential species accumulation curve, with

the estimate obtained by fitting a loginormal distribution

curve to the species abundance plot, I gained a knowledge of

these techniques and their relative value.

Several diversity indices which reduce the number of

species and their relative distributions to a single statis-

tic were calculated. Their utility in describing a collec-

tion could then be tested, as could the effects of environ-

mental factors on these indices.

The use of various multivariate statistical techniques

and numerical ecological methods not only illustrated their

utility for ecological research but also helped define the

important parameters and their interactions in these water-

hyacinth cormmunities and the methods which could be used to

detect them.


Eichhornia crassipes (Martius) Solms-Laubach


The waterbyacinth, Eichihornia crassipes, is a widespread

aquatic weed. The most recent botanical treatment of this

species is probably by Agostini (1974, p. 305), whose descrip-

tion of the species, as translated by Center (1976, p. 5), is:

Plants floating or sometimes fixed to the
substrate, the leaves in the form of a
rosette with the stem reduced and the plants
connected by an elongated horizontal rhizome;
numerous plumose roots issue from each plant.
The aerial leaves are variable in shape;
petioles of 2 to 30 cm long are more or less
inflated; stipules 2-15 cmi long with a small
apical orbicular-reniform lamina with a
lacerate [serrate?] margin; submcered leaves
never evident. Inflorescence variable,
internodes between the spathes nearly ab-
sent; inferior spathe within lamina 1-5 cm
long, thle sheath 3.5-7 cm long. Flower 4-6
em long; perianth light purple or rarely
white, tube 1.5-2.0 em long, lobes 2.5-4.5
cm long, with entire margins. Stamens all
exserted, filaments villous-gladular. Cap-
sule elliptical, trigonous, 12-15 mm long;
seeds oblong-elliptical 1.2-1.5 x 0.6-0.6
mnm with 10 longitudinal ridges.


Eichhornia is one of 9 genera, all aquatic, of the

pickerelweed family, Pontederiaceae, all but 2 of which are

considered endemic to the NowJ Uorld (Cook et al. 1974). The

waterbyacint~h is the most widespread of the 7 species of

this mainly neotropical genus. E. crassipes is the only

member of the genus found in the United States, although

there are reports of E. azurea (Sw.) Kunth in South Flori-

ida (Burkhalter 1974).

Waterbyacinth first received the attention of European

taxonomists during the beginning of the nineteenth century,

and Bock (1966) has an excellent historical review of the

taxonomy of this species. Center (1976, p. 3) cites Agostini

(1974) for the following synonomy for Eichhornia crassipes:

Eichhornia crassipes (MTart.) Salms in DC., Monogr.

Pontederia8 cassipes Mart., Nov. Gen. 1:9.

Parops crass pes (Mart.) Raf., Fl. Tell. 2:

Eichhornia speciosa Kunth, Enum. Pl. 4: 131.
Eichhornia cordifolia Gandog., Bull. Soc.
Bot. France TREETT 1920.

The scientific synonyms E. spcis and Piaropus cras-

sipes are especially common in the literature even 50 years
after Solms-Laubach's revision.

WJhile the binomial Eichhornia crassipes has gained wide-

spread acceptance in the last 30 or 40 years, the authorship

of the name is often confused, sometimes being mistakenly

attributed to Kunth. The correct form for the scientific

name with the authors abbreviated is "Eichhornia crassipes

(THart.) Solms'

E. crassies_ has a variety of common names in different

parts of the world, with Bock (1966) listing 48 names from

18 countries. In the English language the name waterhyacinth

is commonly used. The structure of the name varies, however,

sometimes being written as one word (waterhyacinth), as a

hyphenated word (water-hyacinth), or most frequently as two

words (water hyacinth). Although most modern authoritative

botanical works (e.g. Cook et al. 1974, Muenscher 1967,

Stodola 1967) use the two-word form "water hyacinth," I will

use the single-word form "waterhyacinth," as recommended in

Kelsey and Dayton's (1942) list of standardized plant names

and in the Composite List of Weeds by the Subcommittee on

Standardization of Common and Botanical Names of Weeds (Anon-

ymous 1966).


Waterhyacinth, now generally believed to be a native of

South America, is widely distributed throughout the tropical,

subtropical and, occasionally, temperate regions of the world

(Holm et al. 1969, Bock 1966, Center 1976). Although some

earlier workers consider waterhyacinth a native of Florida

(Buckman 1930, Small 1933, Muenscher 1967), most agree that

it was introduced. Goin (1943) cites a University of Florida

botany professor with crediting the U. S. introduction of

w~aterhyacinth to the Venezuelan delegation to the 1835 Cen-

tennial Exposition, with waterhyacinth subsequently being

introduced about 1840 into Florida by cattle-growers. There

is an amazing reference (Gowanloch 1944) that waterhyacinth

was introduced to South Almerica from Japan. This report is

probably due more to wartime emotionalism than scientific

fact. Penfound and Earle (1948) mention that it may have

been cultivated as a greenhouse plant as early as shortly

after the Civil War. As Bock (1966) points out, it is dif-

ficult to believe that a species as large and showy as water-

hyacinth was overlooked until the late 1880's by all the

early botanists in the state. M~ost authorities agree that,

directly or indirectly, the waterbyacinths in Florida came

from those brought from Venezuela by the Japanese delegation

for distribution as souvenirs at the 1884 International

Cotton Exhibition (sometimes referred to as the 1884 Cotton

Centennial Exhibition) in New Orleans (Klorer 1909, Buckman

1930, Penfound and Earle 1948, Tabita and wJoods 1962).

Although the precise time and area where waterhyacinths

were introduced into Florida is not surely known, the earli-

ast reports place it in the St. Johns River near Palatka in

1890. A New York newspaper account (Anonyvmous 1896) quotes

a N~r. J. E. Lucas of Palatkca that th~e waterhvacinths were

introduced by a M~r. Fuller [in 18911 into the St. Johns

River- seven miles north of Falatka at EdgewJater Grove from

plants brought originally from Europe. Webber (1897) places

the point of introduction ". . about 1890, at Edgiewater,

shout four miles north of Palatka" (p.11), while Tilghman

(1962), an old resident of Falacka, states "Florida's first

water byacinthl was placedl in the St. Johns River by a winter

visitor, Mlrs. W. F. Fuller, at San Ilateo, five miles south of

Falatka" (p7. 8). Most subsequent workers (Buckman 1930, Penfound

and Earle 1948, Tabita and Woods 1962, Seabrook 1962, Zeiger

1962, Raynes 1964, and many others) give similar versions of

thle introduction based directly or indirectly on the above


In 1897 waterbyacinth distribution in Florida was thought

to be confined to the St. Johns River and its tributaries and

a f~ew landlocked lakes (Webber 1897). In 1930 waterhyacinths

seemed still to be confined to the 42-square-mile (26,800

acres) St. Johns River drainage (Buckman 1930). By 1947 the

estimated area of infestation increased to 63,000 acres and

to approximately 80,000 acres by 1962 (Tabita and Woods 1962).

In 1964 an estimated 90,000 acres were infested (Ingersoll

1964), while by 1972 the estimated area of infestation had

increased to 200,000 acres (Perkins 1973). The 1975 estimate

is also 200,000 acres (Center 1976).

P'ro ductivity and Regraduction"

This increase in the area infested, despite massive con-

trol measures dating backed over 75 years, points out the re-

markanble reproductive ability of this plant. Considered

one of the world's most productive photosynthetic organisms

(WJestlake 1963), waterbyacinth-s under optimal conditions

may~ double in number in 11 to 18 days (Penfound and Earle

1948). Center (1976) presents a table on waterhyacinth pro-

ductivity an-d SLanding crop comp~iledl from many different


Such rapid increase in new plants is due primarily to

vegetative r-eprodluction (Hitchcock et al. 1950), with one

plant producing many offsets, or suckers, on stolons (Pen-

found and Earle 1948). New plants are also regenerated

from broken portions of the rhizome (ibid.).

Unlike California and some other parts of the world

(Bocke 1966), in Florida reproduction from seed definitely

occurs, with about 5% germinating under normal conditions

(Zeiger 1962). Seeds are considered important in Florida

chiefly as propagules for infesting new areas or for rein-

festing areas where waterhyacinths had been controlled.

Environmental Requirements

Although it is frequently believed that the absence of

waterbyacinths in a suitable body of water is due to the lack

of introduction of a propagule (Penfound and Earle 1948),

this is probably an over-simplification As Morris (1974)

points out, an invading organism's success is due not only

to favorable physical factors such as nutrients, light and

temperature, but also to the competitive ability of plants

already present in the area. He demonstrated that waterhy-

acinths would not become established when introduced to an area

with abundant native vegetation. However, man frequently

alters these natural, balanced, aquatic systems, sometimes

by increasing the nutrient level. A good colonizing species

lilke w~aterhyacinth can easily become established and out-

compete the native flora in such disturbed aquatic systems.

L~ight. Waterbyacinths require reasonably high light

intensities for growth, at least 60% full sunlight according

to Bock (1966). Penfound and Earle (1948) found that the

light intensity in July above a waterhyacinth mat was 420

footcandles and noted that plants at 130 footcandles were

dying. Knipling, et al. (1970) foundl that photosynthesis

increased fromm 7.8 mg CO2/dm" leaf surface/hr to 16.1 mg/
dm2/hr when light intensity increased from 1450 to 8000


Air temperature. W~aterbyacinths can easily survive

freezing temperatures for short periods of times, Webber

(1897), Buck (1930) and many subsequent workers observed re-

growth of shoots from the submerged rhizome after the tops

of the plants had been killed by frost. Survival at 21oF

for 12 hrs has been recorded, with lower temperatures killing

the rhizome and preventing regrowth (Penfound and Earle 1948).

I could find no literature on optimum or maximum air tempera-

tures for waterhyacinth; however, it is undoubtedly fairly

high,, as most prolific growLh usually occurs during summer

when daytime temperatures are frequently in the uppier 80's

and low 90's oF. Balciunas (unpublished data) observed lux-

uriant growth in a greenhouse where daytime summer tempera-

ture wJas consistently about 1000,.

later temperature. Knipling et al. (1970) determined

that the optimum water temperature for waterhyacinth was

28-30"C (82.4-86.00F) but that growth was relatively high

over the range of 22-350C (71.6-95.0"F'). Waterhyacinths

w~ill survive a water temperature of 34"C (93.2oF) for 4 or

5 weeks (Penfouind anid Earle 1948), but higher temperatures

are detrimental, with negative growth occurring at 40"C (1040F)

Wat-er dyth.l' Waterb!yacinths can g:rowd on land; P'enfound

and Earle (1948) noted survival of plants for up to 18 days

out of water. A high soil moisture content seems necessary

for prolonged survival (Webber 1897, Bock 1966).

There seems to be no good correlation between increasing

water depth and waterbyacinth growth (Mlorris 1974).

Water Quality_

Hydrogen ion concentration. w~aterbyacinth seems tolerant

to pH values normally encountered in aquatic systems. Haller

and Suitton (1973) found that optimal growth occurred in acid

to slightly alkaline conditions (pH 4-8) and some growth oc-

curred from pH 8.0 to 10.0. Bock (1966), citing various

sources, gives a pH range of 4 to 9. Ponfound and Earle (1948)

found that the pH of water beneath waterbyacinths usually

ranged from 6.2-6.8 but th~at wvaterhyacinths could tolerate

extremes of 4-5 and 9-10. Chadwick and Obeid (1966), in com-

paring growth of waterhyacinths and wjatertectuce (Pistia

stratiotes L.), found that optimal growth for waterhyacinths

occurred at a pH of 7.0 while 4.0 was optimal for waterlettuce.

Center and Balciunas (1975), comparing water quality at vari-

ous locations having waterbyacinths, alligator weed (Alter-

nanlthera ILhiloxeroides (Mart.) Griseb.), or neither weed,

found there was little difference in the pHI preferences of

the plants and that the pHI of areas with waterbyacinth was

slightly lower (7.06 + 0.84t), though not significantly, than

the pH of areas having no arlu~atic weeds (7.55 + 1.06).

NTutrients. Dymond (1948a) and Hlitchcock et al. (1949)

found that wYaterhyacinths grow well in nutrient-poor as well

as in nutrient-rich water but that added nutrients favor

growth. Haller et al. (1970) found that less than 0.01 ppm

phosphorus was limiting to waterbyacinth growth and that above

this level phosphorus was absorbed in luxury amounts. Haller

and Sutton (1973) found that maximum growJth occurred in water

with a phosphorus concentration of 20 ppm and that levels

greater than 40 ppm were toxic. Boyd and Scarsbrooke (1975)

added fertilizer at 4 different levels to waterbyacinth ponds

and found that the lowest waterhyacinth biomass yield was

from unfertilized ponds while the highest yields came from

ponds with the intermediate level of fertilization.

Wahlquist (1972) compared yields of waterhyacinths grown

with no fertilizer, with fertilizer containing phosphorus,

and with fertilizer containing both nitrogen and phosphorus.

He found that fertilized ponds had much higher yields (550.4

and 590.9 metric tons/ha) than unfertilized ponds (174.5 metric

tons/ha) and that ponds fertilized with nitrogen and phos-

phorus had a slightly higher (but statistically insignificant)

yield than ponds fertilized with phosphorus only.

Salinity. Although plants can survive up to 13 days in

100i: seawater (Bocke 1966), waterbyacinth~ is intolerant to salt

water, with Buckman (1930) listing a survival time of only

24 brs. Penfound and Earle (1948) found that waterhyacinths

did not tolerate more than slightly brackish water and were

not found in lakes or streams with an average salinity greater

than 15% seawater.

Alkalinity. Center and Balciunas (1975) found the alka-

linity of water containing waterhyacinths or alligatorweed was

higher than that: of water without either species.

Metallic ions. Sutton and Blackburn (1971a, 1971b)

found that 3.5 ppm copper for 2 weeks inhibited waterbyacinth


Center and Balciunas (1975) found waterbyacinths more

tolerant of low fron levels than alligatorweed. Morris (1974)

found no correlation between waterbyacinth growth and the

levels of copper and iron at his study sites.

Economic Importance

Problems. The explosive growth of waterbyacinth has

caused it to be ranked as one of the 10O most important weeds

and the most important aquatic weed (Holm et al. 1969). The

massive amount of literature on the problems caused by water-

hyacinth is well reviewed by Del Fosse (1975) and Center

(1976). A list of the maini categories of problems is:

(1) Interference with navigation;

(2) Clogging of water drains, irrigation canals, spray

equipment and pumps;

(3) Interference with fishing, swimming and other aqua-

tic recreational activities;

(4) Oxygen depletion caused by heavy infestations,

making water inhospitable to many aquatic organisms;

(5) Increased evapotranspiration rates in an infested

area (1.5 to 5 times higher than evapotranspiration from ad-

jacent open water);

(6) Reduction of fish populations by destruction of

spawning beds, competition for nutrients and space, depletion

of dissolved oxygen, and by preventing predators from finding

small organisms;

(7) Creation of deep beds of organic sediment;

(8) Reduction of open water available to waterfowl;

(9) Creation of ideal breeding places for certain mos-

quitoes, some of them disease vectors;

(10) Increased flooding due to obstruction of waterways;

(11) Occasional destruction of bridges, trestles and

other structures during flooding;

(12) Shading out and otherwise out-competing beneficial

aquatic vegetation;

(13) Hionetary and ecological costs of control;

(14) Rendering unsightly and aesthetically unpleasant

the water surfaces which they completely cover.

Control. The U. S. Army Corps of Engineers estimates

that a total of $76 million was allocated for aquatic weed

control in Florida during fiscal year 1976, with almost

$5 million being allocated Eor waterbyacinth control (Center

1976). Mlorris (1974) cites a USDA source for a $12-$16 mil-

lion estimate of the costs of waterhvacinth control in Flor-

ida in 1973.

The literature on waterbyacinth control is enormous.

There is even a Hyacinth Control Journal (renamed in 1975

the A~quatic Weed Management Journal) which- began publication

in 1962. Pieterse (1974) provides a good review of the most

important literature on waterhyacinth control. Del Fosse

(1975) has a more detailed review of the various aspects of

waterhyacinth control.

There are also good, recent review articles for each

particular aspect of waterhyacinth control: methods of

mechanical control have been reviewed by Robson (1974); chem-

ical control and the various compounds available were re-

viewed by Blackburn (1974); biological control of aquatic

weeds has been reviewed by Bennett (1974) and by Andres and

Bennett (1975). The use of plant pathogens was reviewed by

Zettler and Freeman (1972), Freeman et al. (1974) and by

Charudatt~an (1975). Mlitchell (1974) reviewed habitat manage-

ment as a means of aquatic weed control.

Utilization. Possible beneficial uses of waterhyacinths

have been a concern of even the earliest reports (Webber 1897,

Buckman 1930, Penfound and Earle 1948). Bock (1966), Pieterse

(1974), Del Fosse (1975), and Center (1976) all review the

abundant literature regarding the beneficial aspects of water-

h-yacinths, th-e main ones of which are:

(1) Removal of nutrients from water, including use of

w~aterbyacinths in sewage treatment;

(2) Protection of shorelines from erosion;

(3) Use as mulch and fertilizer;

(4) Use as a source of production of natural gas;

(5) Increase in aquatic organisms utilizable as fish


(6) Use as fodder for cattle, pigs, catfish or other


(7) Shading out of nuisance submerged plants like


(8) Decrease in breeding habitat for certain mosquito

species (Barber and Hayne 1925);

(9) Use in construction of a large variety of objects,

e.g., chair bottoms, cigar wrappers, ice chests, paper;

(10) Aesthetic appeal of beautiful blossoms and luxuri-

ant green foliage.

Habitat for Aquatic Insects

The insects found beneath waterbyacinths have received

little attention. Most of the literature about insects assoc-

iated with waterhyacinths deals with those which might have

potential as control agents through their feeding activity

or transmission of pathogens. Fred Bennett of the Common-

wealth Institute for Biological Control in Trinidad has

published many papers on insects and mites on waterhyacinth

and their possible use as biocontrol agents (Bennett 1967,

1968a, 1968b, 1970, 1972, Bennett and Zwolfer 1968). Others

who have providedl lists of insects attacking waterhyacinth

are Gordon and Coulson (1969), Coulson (1971), Perkins (1972,

1974), and Spencer (1973, 1974). None of these investigators

mentions any aquatic insects except the weevils, Neochetina

spp., which build their pupal case in the root hairs of water-

hyacinths (DeLoach 1975).

Waterbyacinths' extensive root systems, sometimes over a

meter in length, create a vast new habitat for a variety of

aquatic insects where previously a few larger, predaceous,

open-water forms dominated. Weber (1950) estimates the area

of the roots of one small waterhyacinth is 7.31 square meters.

O'Hlara (1968) believes that wYaterbyacinth has a greater inter-

face area than any other aquatic plant.

Although Goin (1943) thought that the root length of

waterhyacinth plants was dependent on the depth of the water

beneath them, it has been demonstrated that root length is

a function of the nutrient content of the water: the longest

roots occur in nutrient-poor waters, the shortest roots in

nutrient-rich water (W~akefield and Beck 1962, Haller and Sut-

ton 1973, M~orris 1974). The blue color frequently seen in the

roots, often cited as a diagnostic aid, is also due to water

quality. Plants grownI in phosphorus-deficient water have

iridescent blue roots, indicative of anthocyanin production

and phosphorus deficiency, while roots of plants grown in

nutritive waters are a normal, gray-black color (Haller and

Sutton 1973).

While fishermen (Tilghman 1962) frequently praise the

waterhyacinth for producing an abundance of aquatic insects

and other organisms desirable as fish food, most investiga-

tors disagree. They believe the apparent abundance of

aquatic organisms occurs only on~ the edge of a mat, with the

water under the center of the mat being ". . unsuitable for

the existence of most forms of plankton and aquatic insect

life." (Lynch et al. 1947, p. 64). Many agree, citing low

levels of dissolved oxygen beneath a solid mat (Lynch 1947,

Ultsch 1971, 1973). Wahlquist (1969) believes the reduction

of fish yield in waterhyacinth-infested ponds is due to

shading out of phytoplankton by waterbyacinths.

Few workers have actually surveyed the aquatic entomo-

fauna of waterbyIacinths. Goin (1943) surveyed the lower ver-

tebrate forms of waterbyacinth communities but he mentions

only one insect, the midge Chironomus. O'Hara (1961, 1968)

surveyed the invertebrate fauna of waterhyacinth-covered

canals in South Florida and lists the insects collected, most

of which are identified only to family. Katz (1967), in her

study of the effects of chemical eradication of waterhyacinths

on the associated aquatic fauna, provides lists of insects

on and below waterhyacinths. Most of the insects are identi-

fied to the generic level, but I suspect there are many

erroneous identifications. Hansen et al. (1971), in studying

the food chains of aquatic organisms beneath waterbyacinths,

mentions several different aquatic insects. Lynch et al.

(1947) collected a relatively small number of aquatic insects

from beneath waterhyacinths, most of which were identified

to family or order. Wahlquist (1969) also mecntions some in-

sects, identified only to Eamil~y or order, which serve as

food for fishes living in wzaterbyacinth-covered ponds.

The only group of aquatic insects whose relationship

to waterhyacinth has been investigated more thoroughly is

the mosquitoes (Culicidae). Barber and Hayne (1925) list

4 species of Anopheles collected among waterhyacinths, A.

crucians being the most common. Seabrook (1962), in his

study of correlation of mosquito breeding to waterhyacinths,

mentions 2 species of Aniopheles and all 3 species of Mansonia

as being associated with waterhyacinths. He, along with

Barber and Hayne (1925) and Lynch et al. (1947), believes

that waterbyacinths increase mosquito production. However,

Viosca (1924; cited by Barber and Hayne 1925), Mulrennan

(1962) and Ferguson (1968) believe that waterbyacinths re-

duce mosquito production by shading out planktonic food and

the submerged plants which serve as refuges.

The only other references I found to aquatic insects

associated with waterbyacinths are casual references by ento-

mologists to the habitat where a certain species was col-

lected, e.g., Blatchley (1914, 1925), Young (1954).


Aquatic insects were collected 88 times in 37 different

wzaterbyacinth communities in 18 Florida counties. In addi-

tion, 3 study sites in Alachua County (Camps Canal, Lake

Alice, and a drainage ditch at Interstate 75) were sampled

repeatedly in order to ascertain seasonal and other temporal

changes. Twenty-nine collections were made at Camps Canal,

including regular samples at 2- to 3-week intervals during

all of 1974. The first collection was made 12 Aug. 1972,

the last on 5 Dec. 1974. Table 1 presents a list of collec-

tion sites and dates.

Sample Site Selection

The exact sampling point at a given collection site was

selected on the basis of several considerations. An area

containing an essentially pure stand of waterhyacinths was

chosen in order to eliminate complicating effects which

other aquatic or successional plants might have on the biota

beneath a waterhyacinth mat. The w\aterhyacinth communities

sampled were essentially monotypic, although almost all con-

tained small amounts of duckweed, Lemna and Spirodella spp.

and/or some water fern, Salvinia and Azolla spp. Watermeal,

Wolfia spp. and Wolfiella spp., was sometimes present mixed

with the Lemna. These floating macrophytes were seldom






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abundant except in a few places where waterhyacinth growth

was poor and the waterbyacinth plants widely separated from

each other. Emergent, rooted aquatic vegetation such as

cattails, Typhus sp., and grasses was sometimes present along

the shoreline, but submerged aquatic plants were almost never

present beneath the waterbyacinth mat, although they were

sometimes within the sampling area.

Within a mat a sampling point which was some distance

(2-20 meters) from the shoreline was usually chosen in order

to eliminate ecotone and emergent vegetation effects. The

sampling point was reached by wading if water depth and bot-

tom configuration permitted; otherwise, 2 Styrofoam billets

allowed me to reach and sample the interior of the mat by

alternately standing on one billet and moving th~e other.

Accessability was another consideration. Since a con-

siderable amount of equipment, e~g. Hach test kit, Styrofoam

billets, sampler, collecting and recording equipment, had to

be transported, suitable sampling areas near roads were usu-

ally favored.

Collection Methods

The collections made in 1972 (#1 #'7) were strictly

qualitative, with no attempt at standardization.

Standardized collection time. The 1973 collections,

along with those from the early part of 1974 (#11 #58),

were made on a standard-time basis, i.e., a waterbyacinth

mat was sampled for approximately 1 hour, usually divided

into 2 half-hour subsanpl~es.

If the waterbyacinth mat was not too thick, a triangular

dip net was placed well under the plants and a clump of water-

hyacinths was lifted inside the net out of the water. The

contents of the net and the waterbyacinths were washed in a

pail of water, then small portions of wrater from the pail

were poured into a white enamel pan and searched for insects,

which were placed into a vial of 70"% alcohol. Each vial had

a collection number placed inside and also written on the

stopper. Once all the water in the pail had been searched

for insects, the entire procedure was repeated until the

time period elapsed.

The entire contents of the pail were searched even if

the time period ended before all the water had been examined.

Actual time spent collecting the insects, as wjell as number

of plants and petioles searched, their height above the water,

root length and water depth were recorded. Offsets were con-

sidered plants if a root system had developed; petioles were

counted only if they had a portion of a green leaf.

If a mat was too thick, i.e., the numerous stolons and

petioles prevented passage of the dip net, then a clump of

waterhyacinths would be quickly pulled out of the water into

the pail, the roots washed and the water examined as previously

outlined. This standardized collection time method or "catch

per unit effort" is a valid way of estimating insect popula-

tion density (Morris 1960), however, preliminary analysis of

my data showed that extension of these type data could lead

to spurious conclusions.

Standardized area. A~ sampler which would cut through

a waterbyacinth mat and capture the organisms underneath was

designed and constructed. It consisted of a rectangular
aluminum box, 80 x 40 x 50 cm, open at both ends, reinforced

with an external frame and with strips of sharpened stainless

steel attached to the bottom edge. The sampler, when brought

down vigorously in a vertical position on top of a waterbya-

cinth mat, cut a 1/5-square-meter (0.2 m2) section out of the

mat. A 10-cm high aluminum drawer with a double mesh bottom

was then quickly inserted into a slot 15 cm from the bottom

of the sampler, thus enclosing the waterbyacinth mat sample

and aquatic organisms beneath it in the sampler.

The sampler was then lifted out of the water, the water

was drained through the screen drawer, and the drawer was

searched for aquatic organisms, washed and searched again.

Roots of waterbyacinths trapped inside the sampler were washed

vigorously in a bucket of water and the water was searched

for aquatic organisms. Although some active organisms might

have eluded capture by swimming straight dlown before the

drawer could be inserted in the sampler, the presence of

numerous fish, crayfish and other active swimmers inside the

sampler indicated that it was reasonably effective in cap-

turing the organisms beneath the waterbyacinth mat. As with

the standard-time sampling method, plant height, root length

and water depth as well as number of plants and petioles in-

side the sampler were recorded. Water temperature at a depth

of approximately 15 cm was also recorded.

WJater QualityL

Water quality data for each collection site were taken

in the following manner. Three water samples were drawn

from a depth of about 15 cm in pint-sized Whirl-pakR plastic

bags labelled with the collection number. Total alkalinity,

total hardness, pH and specific conductance of one sample

were tested immediately, using a portable H~ach DR-EL/2 test

kit. At the laboratory, the second sample was tested with

the Hach kit for chlorides, total nitrates and nitrites,

total phosphates, and sulphates. The third water sample was

refrigerated until delivered to the University of Florida

Soils Laboratory, which conducted a variety of tests, of

which those for copper, potassium and iron were the most im-


The methods applied to the water samples were:

alkalinity (total)--tieration;

chloride--titration, mercuric nitrate;

cop~per--atomic absorption spectrophotometer;

hardness (total)--titration, Titra Ver;

iron--atomic absorption spectrophotometer;

nitrates and nitrites (total)--cadmium reduction;

pH--calorimetric, wide-range ;

phosphates--ascorbic acid, P'hos Ver III;

potassium--flame emission spectrophotometer;

specific conductance--direct measurement, conduc-

tivity probe;

sulphlates--turbidimetric, Sulfa Ver IV.


Identification, labelling and cataloging of the thou-

sands of specimens collected took place in the laboratory.

Of the organisms collected, only aquatic insects were iden-

tified. Aquatic insects were defined as those having at

least one life stage which spent time in or on the water.

This definition excluded insects living inside the water-

hyacinth plant and those found on the emergent portion of

the plant.

I identified the specimens using taxonomic keys and

referring to identified specimens at the Florida State Col-

lection of Arthropods and to the original species description

and other taxonomic papers. Although most groups lacked keys

to nymphal stages, I was able to identify the nymphs of al-

most all groups after examining many specimens and construct-

ing life series.

Since there are few keys for larval forms (especially

to species level), I originally attempted to rear many of the

larvae collected. However, the lack of adequate facilities

and time to rear these many aquatic larvae with their diverse

requirements, andi the subsequent loss of some specimens and

poor quality of others caused the termination of this approach.

Subsequently all larvae were preserved in the field along with

the other insects. Some larvae were identified by experts on

the groups.

I identified the mayfly (Ephemeroptera) nymphs using

Berner's (1950, 1968) keys, and Dr. Lewis Berner of the

University of Florida kindly checked the identifications of

some representative specimlens.

Dragonfly (0donata:An~isoptera) nymphs were identified

using the keys of Wright and Peterson (1944) and Needham and

Westfall (1955). Damselflie~s (0donata:Zygoptera) were

especially difficult to identify since no comprehensive key

to species exists, but by using Walker's (1953) descriptions

and other species descriptions as well as characters provided

by Dr. Mlinter J. Westfall of the University of Florida, and

by constructing life series, I was able to identify all speci-

mens, including very early instars. Dr. Westfall examined

and verified all my odonate specimens.

Aquatic Hemiptera were identified using the keys of

Herring (1950a, 1950b, 1951a, 1951b) for most families.

Velvet water bugs (Hebridae) were identified using Chapman's

(1958) key; water-crawling b~ugs (Naucoridae) were identified

using La Rivers' (1948, 1970) keys and by construction of

life series of nymphal stages. Dr. Jon Herring, USDA Syste-

matic Entomnology Laboratory, confirmed my identifications of

representative specimens of different species of aquatic and

semi-aquatic Hemiptera except for the giant water bugs

(Belostomatidae), which were checked by Dr. Mencke at the

Smithsonian Institution.

Caddisfly (Trichoptera) larvae were determined using

W~allace's (1968) kev. Dr. Oliver Flin= at the Smithsonian

checked all my caddisfly identifications. Species level

determination was frequently impossible.

Dobsonfly (M~egaloptera: Corydalidae) larvae were iden-

tified with the keys of Chandler (1956) and Cuyler (1958).

Adult water beetles (Coleoptera), except Hydrochidae,

were identified by using Young's keys (1954, 1956, 1963).

Hydrochidae were identified by Dr. John L. Hellman of the

University of Mlaryland. The larvae of aquatic beetles could

not be easily identified, though Leech and Chandler's (1956)

keys in Aquatic Insects of California were of some value in

identifying larvae of some families to the generic level.

Species level determination was possible only for genera

monotypic in Florida. Dr. Paul J. Spangler of the Smithson-

ian Institution graciously identified or confirmed my iden-

tifications of all aquatic beetle larvae except Helodidae.

Helodidae larvae are very poorly known and even the identi-

fication of adults was very difficult. I was successful in

rearing some larvae to adult stage. Dr. Dale Habeck, Univer-

sity of Florida, and I wJere then able to find characters to

discriminate the different genera. Dr. Frank Young at the

University of Indiana checked all of my aquatic beetle adults

except the adult: Hydrophilidae, which were checked by Dr.


Dr. Dale Habecke also identified the aquatic Lepidoptera


Mosquito larvae (Culicidlae) were readily identified to

species using Carpenter and LaCasse (1955). Dr. William Beck

of Florida A & M graciously identified all thousand-odd of

my midge (Chironomidae) larvae specimens. Other families of

Diptera larvae could be identified to the generic level using

keys of Wirth and Stone (1956), while a few (17 specimens) of

Diptera larvae and pupae could be placed only at the family


After all specimens had been identified and recorded,

comparison of the species composition of different collec-

tions was desired. With the number of species in a collec-

tion ranging from 1-31 and the number of specimens in a col-

lection from 3-373, direct comparisons of species composition

of collections was difficult. In ecological studies it is

common to represent the numbers of species and their relative

distribution by a single statistic, an index of species


The choice of diversity indices is enormous, with much

confusion about terms and applicability (Hlurlbert 1971, Peet

1974). Mluch of the confusion results from the dual concepts

which~ most, but by no means all, authorities believe an in-

dext of diversity should embody. Almost all agree that species

richness, the number of species in a sample (sometimes re-

ferred to as species number or species count), should be re-

flected in the species diversity index used. Many research-

ers, especially outside the field of ecology, in fact tend to

equate diversity with species richness, i.e., a collection

has "high diversity" because many species are present. How-

ever, this reliance exclusively on species richness does not

take into account the relative abundances of each species.

T'he species evenness or equitability concept of diversity

stresses these relative abundances, equating high diversity

(more properly, high equitability) with~ an even distribution

of individuals among the species present, while low equit-

ability implies a few abundant species, other species being

relatively rare. MIost authorities in this area agree that

a proper measure of species diversity includes both species

richness and species equitability components (Margalef 1969,

Pielou 1969, Peet 1974). H~urlbert (1971), among others, would

restrict the term diversity to this dual concept.

Because of the preponderance of authoritative opinion

favoring a diversity index with both richness and evenness

components, classed by Peet (1974) as heterogeneity indices,

my investigations were limited to this type.

Peet (1974), in his excellent review article on diversity

indices, lists 4 commonly used heterogeneity indices. E. H.

Simpson proposed a diversity index in 1949 which recognized

the dual concept of diversity and which bears his name. Simp-

son's index, with slight modifications, is extensively used

and is recommended, at least for certain applications, by many

authorities (W~illiams 1964, Whittaker 1965, 1972, Sanders

1968, Pielou 1969). Pielou's (1969) restatement of Simpson's

index as adjusted for finite sample size is frequently used:

D = 1 E ng1
i=1 N(N-1)

where N is the total number of specimens in the collection,

n. is the number of specimoens in the ith species, and s is
the number of species in the sample.

MIcIntosh (1967) suggested another index:

Mc~ntosh's index, while receiving attention in review arti-

cles on diversity indices (Pielou 1969, Peet 1974), does not

appear to be frequently used. Peet (1974) considers it a

variation of Simpson's index, while Bullock (1971) criticizes

its applicability and sensitivity.

By far the most popular and widely used index is Shannon-
Weaver's diversity index:

H' = -.1l p. Log p ,

where pi is the proportion of the total specimens comprised

by- the ith species of p.=n./N. Based on information theory,
diversity is equated to uncertainty. As Pielou puts it:

Diversity in this connexion means the
degree of uncertainty attached to the
specific identity of any randomly sel-
ected individual. The greater th~e
number of species and the more nearly
equal their proportions, the greater
the uncertainty and hence the diversity.
(1966a, p. 131)

Although the most popular diversity index, the Shannon-

Weaver~ index is also the most widely criticized. Monk (1967)

and Sager and H~asler (1969) believe this index to be insensi-

tive to rare species whereas Peet (1974) suggests it is most

sensitive to rare species. Fager (1972), Whittaker (1972)

and Poole (1974) believe Shannon's index most sensitive to

species of intermediate importance. Pielou (1966b) believes

it is used frequently in situations where it is not appli-

cable and questions the validity of equating uncertainty with

diversity (1969). Both Pielou (1966a, 1966b) and Peet (1974)

agree that the Shannon-Weaver index is applicable only when

the collection is a random sample drawn from an infinitely

large population pool. For finite collections, such as

light-trap collections, Pielou (1966a) suggests the use of

Brillouin's (1960) index:

H = 1/N log (N!/n,!n,!..ns '

Unfortunately, this involves computing very large numbers.

Any integer factorial greater than 69! results in a number

larger than 10'oo, which exceeds the capacity of even large,

modern computers. Thus, direct calculation of this index

for larger collections is laborious unless a simplifying

method such as Sterling's approximation to the factorial is

employed. Howrever, the substitution of the Sterling's approx-

imation for the factorial results in this index becoming

equivalent to the Shannon-Weaver index (Peet 1974).

Hlurlbert believes that ". . the recent literature on

species diversity contains many semantic, conceptual and

technical problems", so many problems, in fact, that he con-

cludes ". . species diversity has become a nonconcept."

(1971, p. 57 ) He would possibly retain the term if the

meaning of species diversity were restricted to those terms

which combine both species richness and species evenness,

I.e., heterogeneity indices. He believes that there are 2

useful indices, one of which is modification of the rarefac-

tion index E(Sn) proposed by Sanders (1968). This index

calculates the expected number of species, E(S ), the sample

would contain if the number of specimens were scaled down,

i.e., rarefied, to some common number which would allow com-

parison with other samples. The scaling, which was done in-

correctly by Sanders (Hurlbert 1971, Fager 1972, Simberloff

1972), is necessary because larger samples would contain more

species than a smaller one even if they were drawn from the

same community. Hurlbert (1971) and Simberloff (1972) pro-

vide similar, correctly "scaled", calculating formulae for

the rarefaction index:

s~~ -1 n."j "
E(S ) = [ /
n i=1

WThile this results in a scaled estimate of species richness,

and Feet (1974) classifies this as a richness index, I be-

lieve it can be classified under the heterogeneity indices

since the species composition, i.e. the evenness, was used in

the scaling.

I chose the following species diversity indices:

Shannon-Wveaver index, HI', since it is the most commonly used

index in recent ecological literature; Simpson's index, D,

since it overcomes some of the sh-ortcomings of H'; and the

rarefaction diversity index, E(S _), because of its inherent

rationality and ease of interpretation. I wrote a small

Fortran program, shown in Appendix A, which calculates

Shannon's H', Simpson's D, and also Brillouin's H when the

collection is small enough. For these diversity indices,

the choice of the base for the logarithm is left up to the

researcher. Since no particular base seems to have become

standardized, I chose to use natural logarithms, although

the base 2 and base 10 logarithms also are frequently used.

For calculating E(Sn) I modified slightly a program cited

in Simberloff (1972) and Heck et al. (1975) and provided by

Dr. Heck of Florida State University. As a check on the

sensitivity of these 3 indices, I also used a fourth, ex-

tremely simple index, the number of specimens per species,

in all my analyses of diversity.

Efficiency of sampling method and determination of the

total number of species in the community sampled are usually

unanswered questions in ecological studies. A relatively

crude, frequently employed estimate of sample effort (Wilhm

1972, Heck et al. 1975) is the graphical plotting of a species

accumulation curve. The cumulative number of new species is

plotted versus the cumulative number of specimens, with each

collection being added sequentially, hopefully resulting in

a curve such as that shown in Figure 1.

The resultant points initially form a straight line,

as each collection adds a relatively constant increment of

species per specimens collected. However, with increased

sampling only rare species remain, and the line rapidly

curves to become asymptotic at the value of the total number

of species in the community and produces the typical exponential

i /

Tlllllllllli~e spcLii~~n~

Figure i. Generalized species accumulation curve.

1 (ICIS~~11 Per 5venesr

1_ i
) ii II
~i:1* I~

Figure 2. Lognormal species abundance curve
(from Preston, 19148)

sp~ecies accumulation curve. Unfortunately, this asymptote is

frequently attained only when the total number of individuals

sampled is very large, sometim-es only when nearly every in-

dividual in the community has been collected and identified.

In general practice, most researchers use this method to deter-

mine if future sampling will be worthwhile, i.e., whether the

crest or some other previously determined point on a species

accumulation curve has been reached. This is usually done

through simple visual inspection of a graph. The asymptote

level, i.e. total number of species, is not usually calculated.

For my data from my 3 repetitively sampled study sites, I

refined this procedure. A curve such as the one shown in

Fig. 1 can be represented by the general exponential equation:

y = a(1 e-bn)

where a is the asymptote for the curve. Rew~ritten in terms

of thie species notation previously used, this equation be-


s = S* (1 e-bn)

The estimated total number of species in the collecting area,

S*, and the constant, b,, can be determined from a curve fitted

to theP data. Although the computer program SAS PROC NLIN

will fit this general curve to the data, it requires estimates

of both S* and b. While a very general approximation of the

value for S*' can be obtained fromn inspection of the data, the

approximate value for b is not readily apparent. However, I

was able to devise a graphical method for obtaining an esti-

mate for the value of b, which- in turn allowed an estimation

of S*. First rewriting the equation as:

s = S* S~e-b

thien taking the derivative results in:

ds = bS~e-bndn

or, in terms of the slope, ds/dn, of the curve:

ds/dn = bS~e-b

Taking the natural logarithm of both sides results in the

express sion:

In(ds/dn) = In(bS*) + (-bn).

Thus the logarithm of the slope fits the general equation for

a straight line:

y = ~o + ti,x,

where the intercept 00 equals In(bS*), and the slope B, equals

-b. The slope ds/dn of the original equation can be approxi-

mated by AS/An, the increase in the n-umber of cumulative

species over the number of specimens added with each additional

collection. Tihus, plotting In(As/an) against the cumulative

number of specimens, ni, approximates plotting In(ds/dn) versus

n. Fitting a straight line to the rLesultant points by using

the least squares procedure provides the value B,, which is a

good approximation of b. I'ugging this value of b and the

values of a pair of s and n back in to the original equation

results in a point estimate of S*. Using these crude esti-

mates of S* and b allows the use of PROC NLIN to fit the curve

to the data point, which then gives precise estimation of S*

and b. The goodness of fit of the curve to the data points

can be demonstrated by noting the level of significance for

the F' value, calculated by dividing the mean square of the re-

gression by the mean square of the residual. Sampling effi-

ciency was then simply the actual number of species collected

(s) over the expected number of species (S*') or:

sampling efficiency = s/S*,

Another semigraphical method for determining the total

number of species (S*) is by plotting what is termed a species

abundance curve. F. Wi. Preston first presented this method

in 1948 and elaborated on it in 1958 andi 1962. The data are

first arranged according to abundance of individuals in each

species. The species are then grouped, each successive group

representing species with twice as many individuals as the

preceding group or, in other words, on a base 2 logarithmic

scale. The third "octave," Preston's term for the groups,

represents species which have between 4 and 8 individuals.

Any species which falls on an interval boundary is split

equally between both ocen7ves, thus a species containing 4

specimens is counted as contributing one-half to the second

octave (2-4 individuals) anid one-half to the third octave

(4-8 individuals). Thus thle first octave contains half of

the species having a single specimen and half of the species

having 2 specimens. The number of species per octave is then

plotted against the octave, resulting in a curve such as that

shown in Fig:. 2, representing, the species and abundances of

moths caught in a light trap, as presented by Preston (1948).

Note that the left-hand portion of the curve ends abruptly

at the y-axis, called the "veil line" by Preston. The species

to the left of the veil line are those which would be repre-

sented by less than a single individual if collected in the

same proportion as they exist in the sampling area, and they

are, therefore, "hidden by the veil line," to use Preston's

terminology. The general equation of the Gaussian curve

which Preston fits to this and other data is:

s= soe BR)2

where so is the number of species in the modal octave, Ro

(the octave containing the most species), s is the number of

species in an octave which is R octaves from the modal octave,

and a is ". . a constant calculated from- the experimental

evidence" (p. 258). In practice, a is extremely difficult to

determine. It is derived by solving the equation for the

curve which has been fitted to the data. Unfortunately, fit-

ting a truncated Gaussian curve is a very difficult task. The

statisticians in the Departmlent of Statistics at the Univer-

sity of Florida are awaiting arrival of some special statis-

tical. tables to enable themm to do this. Although most texts

dealing with mathematical ecology (Cody and Diamond 1975,

Pielou 1969, Price 1975, Poole 1974) mention Preston and

present his graphs, I have found very few authors (Good 1953,

Patrick 1954) who are able to apply his techniques to their

own data. However, the value of a has been found to be very

close to 0.2 for all data analyzed by Preston (1948, 1958,

1962). The total number of species in the sampling area S*

can then be found from the relation:

S* = so"F/la

As Preston (1948) carefully points out, this theoretical

total number of species is really the total number of species

in the sampling universe, which differs from the total number

of species in the sample area. It represents the total number

of species which would be found if all individuals collectible

by the sampling methods used were collected during the sample

period. For example, the number of species estimated from

light-trap data represents only those species which are in the

vicinity of the light trap and are attracted or blunder into

it. It does not represent the total number of species of all

moths in the collecting area, just the collectible species.

For purposes of comparison, species abundance curves were

fitted by eye to the data for my 3 study sites and the value

of a was assumed to equal 0.2. While extremely rough, the S*

derived by this method can be compared to S* derived from the

species accumulation curves.

For other analyses of my data 1 used the 76.4 version

of a variety of statistical computer programs which collec-

tively are knownm as SAS (Barr et al. 1976). The most commonly

used statistical procedures were standard descriptive sta-

tistics (PROC MZEANr), correlation (PROC CORR), linear regres-

sion (PROC GLM), stepwise multiple regression (PROC STEPWISE),

nonliniear regression (PROC N~LLIN), and discriminant analysis

(PROC DISCRIM). Standard printing and plotting programs

(PROC PRINT and PROC SCATTER) were also used. All computer

analyses were done by the IBMI 370/165 computer (later replaced

by an AMIDAHL 470 V/6) at the Njortheast Regional Data Center

(NERDC) on the University of Florida campus.

Because of the great variety of analyses, the results

will be discussed under three separate headings: general,

study site comparison, and diversity studies.



Comments on Species List

A total of 5485 aquatic insects were found in 88 collec-

tions from 37 sites in 18 Florida counties. Table 1 presents

a list of collections, locations and dates. Some immature

forms could be identified only to genus level, while 17 speci-

mens of immature Diptera could be placed only to family level.

Represented in the collections were at least 147 species of

aquatic insects belonging to 44 families in 8 orders. Of

these 147 species, 38 were represented by more than one life

stage. These immature frorms were treated as separate classes

in all analyses except those involving species counts. An

annotated list of all species collected is presented in Table

2. The species are arranged according to taxonomic groups;

the orders are arranged in the same evolutionary sequence as

in Usinger (1956). Within the orders the families are ar-

ranged alphabetically, as are the genera and species within

the families. For each species the number of specimens col-

lected, the number of sites and counties, as well as a list

of collection numbers is presented. Any significant correla-

tions with physical or chemical parameters as well as associ-

ations with other insect species are noted. Maximum densities

(text continued p. 116)


Table 2. An annotated list of insects collected in
wjaterbyacinth roots in Florida.

Note: All correlations were computed using normalized
(log transformed) data. For each species under the cate-
gories "water quality preference" and "insect associations"
is listed (1) the factor or species with which the species
being discussed is correlated; (2) the correlation coeffi-
cient, r; (3) p, the probability that the correlation coeffi-
cient observed would occur by chance alone; and (4) n, the
number of times the pair of factors or species being con-
sidered occurred together. Only associations with a prob-
ability less than 0.05 (52) of occurring by chance are men-
tioned. WLhile the probability p takes into account the
number of observations, it is overly sensitive at low values
of n. Correlations which have less than 5 Daired observa-
tions (n<5) therefore have not been included. Maximum den-
sity per square meter is given for species collected using
0.2 square meter sampler.

Ephemeroptera (Mlayflies) --N;ymphs

Only 150 mayfly nymphs of 4 different species were

found. Constituting only 2.7%/ of the total insects col-

lected, they were never very numerous except in collection

#87, where 31 specimens of 3 species made up 41.9% of the

specimens collected there. Katz (1967) mentions collecting

the genera Brachycerus, Cloeon, and Hexaeia in addition to

Caenia from h~yacinths in the Withlacoochee River. The first

two genera are probably misidentifications due to their dis-

tribution and ecological requirements. O'Hara (1961) col-

lected Callibaetis floridanus and Caenis diminuta from

waterbyacinth-covered canals in South Florida.


1. Callibaetis floridanus Banks--45 specimens from

12 collections at 8 different locations in 6 counties.

Collections: 2, 20, 21, 45, 48, 50, 75, 82, 87, 88,

98, 102.

Haximumm density: .6/plant or 30/m2 at #87.

Water quality preference: nitrates, r=-.859, p=.028,


Nrymphs of C. floridanus, known to inhabit brackish water,

". . have the widest limits of toleration of any mayfly

nymph in North A~merica" (B~erner 1950, p. 196). Although

this species was collected numerous times in waterhyacinth

roots by myself and by O'Hlara (1961), Berner (1950) does not

believe them common inhabitants of waterh~vacinths due to low

oxygen levels.

I collected the majority of nymphs of C floridanuss

during the summer, especially August. Some were also col-

lected in November through January. The absence of nymphs

during the other six months may indicate a bivoltine life


C. floridanus' high correlation with Shannon-weaver's

diversity index (r=.666, p=-.018, n=6) may indicate that it

is especially sensitive to conditions which help increase

the diversity of species at the site. This is supported

by the highly significant correlation to number of species

(r=.745, p=.006, n=12). The high negative correlation to

the nitrate level, one of the chief causes of eutrophication,

and the high negative correlation to number of plants per

square meter (r=-.963, p-.002, n=6) also points this out.

The relative numbers of this species might, therefore, find

use as an indicator of water quality.

2. Callibaetis pretiosus Banks--14 specimens in 4

collections from 2 different locations in Alachua Co.

Collections: 36, 42, 50, 87.

Maximum density: .25/plant or 12.5/m2 at #87.

Berner (1950) believes C. pretiosus to have similar

ecological requirements as C. floridanus except that it is

not quite as tolerant to high and low pH and to brackish



3. Caenis diminuta W~alker--75 specimens from 24 col-

lections at 13 different locations in 10 counties.

Collections : 2, 3, 5, 26, 27, 31, 45, 48, 52, 75, 80,

82, G5, 87, 88, 89, 92, 93, 94, 97, 98, 100, 102, 103.

Hajximum density: .7/plant or 35/m~' at #87.

Insect associations: Hydroanthu oblongus Sharp,

r=.841, p=.002, n=10.

Mly most commonly collected mayfly, it is also recorded

by O'Hara (1961) and is probably the Caenis sp. collected

by Katz (1967). According to Berner (1930), this species

prefers small ponds, especially with emergent vegetation,

but is usually not found in water covered by waterhyacinths.

There is an extremely significant correlation with the

noterid beetle Hydrocanthus _oblngus which probably indicates

that these species prefer the same set of environmental con-

ditions .

Nymphs were collected throughout the year.

Heptgni idae

4. Stenacron intergu~nc~tau (Say)--16 specimens from

8 collections at 2 locations in Alachua Co.

Collections: 31, 35, 38, 39, 50, 53, 56, 73.

Maximum density: .129/plant at #35; 2/m2 at #73.

Formerly known as Stenonema proximum, S. interpunctatum

nymphs are usually inhabitants of large streams and sand-

bottomed lakes with little vegetation. Dr. Berner (personal

communication) finds their existence in waterhyacinth roots

to indicate a possible broadening of the species' ecological


MIost of my specimens were collected during the fall and

winter months.

Odonata (DraonflieE~s and Damselflies)--Nymphs

Odonata were well represented with 1,027 specimens

(18.7% of the total specimens) in 18 species. Odonates

made up at least half of the specimens in many collections

and constituted 75;/ of the specimens in collection #102.

Odonat-e nymphs were the most common arthropod group in

W~ahlquist's (1969) study of fish food organisms in experi-

mnental ponds in Auburn, Alabama.

Since all odonate nymphs are predaceous, their abundance

implies a latrge prey population. The most probable prey item,

at least in rnumbiers,, would b~e the anliphipod Hyalella azteca

(Saussure). Hansen et al. (1971) reports 66 amphipods per

waterbyacinth plant, but in the field they were probably more

numerous, with a bucketful of water frequently containing

literally thousands of amphipods. O'Hara (1961) recorded

as many as 81,000 per square meter at one site.

Zygo~ptera (Damselflies) Nymphs

This suborder, with 752 specimens, comprised 13.7% of

all specimens and 73.2"/ of all odonates. Damselfly nymphs

were found in most collections, with one species, Ischnura

posita, being found in 53.4% of my collections, making it

the most frequently represented species. While only 7

species and the E~. signatum-pollutum complex were found, 5

of these were collected over 8 times as compared to only 3

out of the 11 species of Anisoptera nymphs. O'Hara (1961)

found Ischnura ramburii (Selys) and Enallagma sp. nymphs

beneath waterhlyacinths in canals, while K~atz (1967) records

4 gienera of damselflies from waterhvacinth roots at the

Withlacoochee River.


Of the 3 families of damselflies known from Florida,

this was the only one which was found beneath waterbya-

cinths. Of the 35 species in this family that occur in

Florida (Johnson and WJestfall 1970) 7 were collected in

waterbyacinth roots.

5. Argia apicalis (Say)--1 specimen collected at Lake

Talquin, Gadsden Co.

Collection: 96.

Density: .05/plant; 5/m2

Due to the rarity of this species in my collections,

no significant conclusions can be drawn concerning its

preferences or associations. While usually considered a

stream species (Walker 1953), it has been recorded from ponds

in Indiana (Montgomery 19414).

6. Argia sedula (Hagen)--39 specimens from 3 locations

in 3 counties.

Collections: 48, 102, 103.

MIaximum; density: .769/plant at #-48; 35/m2 at #,103.

This species was rarely collected. Walker (1953) states

that the habitat of this species is "streams with gentle cur-

rent and rich vegetation on the banks" (p. 144). All 3 times I

collected this species were in streams and rivers of South

Florida during mid December of 1973 and 1974.

7. Enallagma pollutum (Hagen)--2b specimens from 8

collections at 2 places in Alachua Co.

Collections: 17, 18, 31, 38, 72, 75, 82, 94.

Maximum density: .364/plant at #17; 7.5/m2 at #~75.

Nymphss of this species are extremely difficult to dis-

tinguish from E. signatum nymphs. Only larger, last instar

nymphs could be separated with confidence by counting the

number of spines on the caudal lamellae. Smaller nymphs

wer~1e classed no belonging to thle EE1Em signatum-pollutum

complex. No water quality preferences for this species were

noted. All but 3 specimiens were collected from Camps Canal

east of Mlicanopy. All were found between mid-Mlay and

mid-November. Since this species has a significant, nega-

tive correlation with Simpson's diversity index (r=-.826,

p=.012, n=8), it may be a low diversity indicator.

8.Enallagma signatum (Hagen)--25 specimens from 9

collections at 4 locations in 2 counties.

Collections: 38, 42, 50, 53, 56, 75, 87, 96, 99.

Miaximnum density: .35/plant and 35/m2 at #96.

With- only last instar nymphs distinguishable from E.

pol1utum, this species was collected mainly from November

through February. A strong negative correlation (r=.774,

p=.022, n=9) with the number of species may indicate that

older nymphs of this species would not be expected at a

place which has numerous species.

Enallagma signatum-eollutum complex--119 specimens

from 22 collections at locations in 6 counties.

Collections: 2, 3, 17, 18, 27, 31, 35, 38, 42, 45, 48,

50, 56, 72, 73, 75, 78, 83, 94, 96, 102, 103.

Maximum density: .515/plant at #',17; 35/m2 at #102.

WJater quality preferences: pHl, r=.740, p=.023, n=9;

temperature, r=.755, p=,050, n=7, depth, r=-.519, p=.019,

n=20; chloride. r=.880, p=.004, n=8: potassium, r=.866,

p=.005, n=8.

Tnsecr as-.ociations: nIlvdrocanthus ob~longus Sharp,

r=.655, p=.040, n=10.

Young Enal~lam nymphrs which could be determined as

belongiing Lo either E~. pallutum or E. signatum but whose

exact species remained unktnown due to their small size and

undeveloped dliagnostic characters were placed in this group.

This species complex was found in shallower water which was

high in chlorides and potassium and had a high pH. It was

correlated with the presence of H_. oblongus These nymphs

were collected throughout the year.

9. Ischnura pos ta (H-agen)--319 specimens from 47 col-

lections at 17 locations in 9 counties.

Collections: 2, 3, 4, 7, 11, 13, 17, 20, 21, 27, 32,

35, 38, 40, 41, 42, 43, 45, 47, 48, 49, 50, 51, 52, 53, 54,

55, 56, 57, 69, 70, 71, 72, 73, 74, 75, 78, 85, 86, 87, 88,

90, 94, 98, 101, 102, 103.

Maximum density: .575/plant at #70; 80/m2 at #69.

Water quality preference: nitrates, r=-.477, p=.045,


Insect associations: Belostoma spp. nymphs, r=.779,

p=.008, n=10: Pelocoris femoratus (Palisa~t-B~eauvois), r=.806,

p=.0001, n=22; Ranatra australis Hungerford, r=-.774, p=.041,


While it was only the fourth most numerous in specimens

collected, i. posita was found in 53.4Z of my collections,

more than any other species. It was present throughout the

vear but reached peak density in the springs,. It appears to

prefer less outrophic waters, i.e., those with less nitrates.

It wans generally found when Ranatra australis was present in

low numbers and when Belostoma spp. nymphs were abundant.

There was an extremely significant correlation with Pelocoris

femoratus, with P. femoraLus being collected only 7 times in

the absence of I. posita. The strength of this association

suggests to me that I. posita may be a preferred prey item

for P. femoratus and/or they both share a common food re-

source such as the amphipod Hyalella azteca (as opposed to

sharing an uncommon food resource). It is possible that

this correlation reflects some unknown symbiotic relation-

sh-ip between th-ese two species. The Ischnura ramburii re-

corded by O'Hara (1961) may have been misidentified I.

posita since the nymphs are very similar and the pigmentation
of the caudal lamellae, which is used as a diagnostic char-

acter, is quite variable or absent in smaller nymphs.

10. Telebasis byersi Westfall--220 specimens from 26

collections at 8 locations in 4 counties.

Collections: 2, 21, 24, 27, 32, 36, 37, 39, 40, 41, 42,

43, 47, 49, 51, 52, 54, 55, 70, 71, 75, 85, 87, 88, 90, 97.

lMaximum density: 1.67/plant at #39; 70/m2 at #97.

Insect associations: Brachyvatus seminulum LeConte,

r=-.918, p=.028, n=5; Scirtes larvae, r=-.886, p=.045, n=5.

The second m~ost numerous odonate in my collections,

T. bversi w~as found in 29.5% of my collections, which ranked

it n:; l~enth in nui~mber of collections in whiich it was present

and sixth in Lotal number of specimens. It was found through-

out the year. Florida specimens of this species were thought

to be Telebasis salva until W~estfall described T. byersi in

1957. 10m~ile there are significant negative correlations

with 2 species of aquatic beetles, no water quality prefer-

ences were noted. Since T. byersi keys out as belonging to

the genus Nehalenia in most keys, it is probable that the

Nehalenia recorded by Katz, (1967) from waterhyacinth roots

was really T. byersi.

Anisoptera (Dragonflies) NymI~Phs

With 275 specimens (5% of the total specimens collected),

this suborder was not as numerous as the damselflies and made

up only 26.7'i of the odonates collected. However, while dam-

self lies were represented by 1 family and 7 species, 11 spe-

cies in 5 different families of anisopterans were collected.

Of these anisopteran species, 5 are represented by only one

specimen and only 3 species were collected more than 3 times.

While usually not numerous, they were occasionally abundant,

comprising 66.4% of the 122 specimens found at collection


O'H~ara (1961) collected 5 species of A~nisoptera from

waterhyacinth-covered canals while Katz (1967) records 8

different species. I collected 4 species in common with

O'H~ara but did not find any Brachymesia (=Cannacria) gravida

(Calvert). While I collected only 3 species in common with

Katz, several of her determinations are suspect, e.g. Dythemis

sp. and Ndannothemis bella are both thought to be found in

Florida only in the western panhandle region.


Hith only 5 specimens in 3 species, this family was rarely
found beneath w~aterhyacinthls and neither O'Hara (1961) nor Katz

(1967) record any aeshnid species.

11. Anax junius (Drury)--1 specimen collected at Camps

Canal in December 1973.

Col lec tion : 42 .

Density: .31/plant.

12, Boyeria vinosa (Say)--1 specimen collected in a

stream in December 1973.

Collection: 47.

Density: .026/plant.

13. Coryphaeschna ingens (Rambur)--1 specimen collected

at Camps Canal in December 1973.

Collection: 42.

Density: .031/plant.

Byers (1930) records this species from w~aterhyacinth.

14. Nasiaeschna pentacantha (Rambur)--3 specimens

from 3 collections at 2 locations in 2 counties.

Collections: 35, 45, 50.

Maximumm density: .077/plant at #45.


15. ITe~tragoeuri cynosura (Say)--2 specimens from 2

collections at a small stream in Alachua Co.

Collections: 27, 87.

H~aximium density: .05/plant or 2.5/m2 at #87.

This genus is now~ considered by some authorities to be

part of Epiptheca. Both O'Hiara (1961) and Katz: (1967) col-

lected Tetragioneuria sp. from waterhyacinths.


Most members of this family are burrowing forms and

are rarely found beneath waterbyacinths.

16. Aphyla williamsoni (Gloyd)--1 specimen collected

at Camps Canal on 29 Mlay 1974.

COLlection: 73.

Density: .997/plant or 1/m2

The one specimen I found of this species was a fully

developed nymph from which the adult was starting to emerge,

indicating that it had been knocked into the water from the

aerial portion of the plant where emergence was taking place.

This species lives on the bottom and may be present on water-

hyacinth roots only when moving out of the water for emer-

gence. Katz (1967), however, also recorded this species in
one of her collections.


With 266 specimens in 5 species, libellulids were well-

represented. Two of the species were my tenth and eleventh

most abundant overall. Of the Anisoptera I collected, 96.7%

were members of this family.

17. Erythemis simplicollis (Say)--36 specimens in 9

collections at 9 locations in 4 counties.

Collections: 2, 3, 13, 21, 45, 47, 83, 86, 87.

Maximum density: .615/plant at //45; 40/m2 at #85.

This species was not usually very abundant in my col-

lections, but 18 of the 29 odonate nymphs found by O'Hara

(1961) in waterbyacinth mats were E. simplicollis. My

specimens were all collected in late summer or during Decem-


18. Miathvria marcella (Selys)--116 specimens from 10

collections at 9 locations in 6 counties.

Collections: 5, 7, 20, 30, 31, 47, 75, 88, 100, 102.

Hlaximum density: 5/plant or 400/m2 at #102.

While this w~as my most abundant Anisoptera nymph, 69%!

of all the specimens of this species were found in collection

#'102. O)'Hara (1961) recorded th-is species. Katz (1967) did

not report this species, possibly due to its absence from the

keys she used. Byers (1930) did not find this tropical spe-

cies in Florida, while today this is one of our more common

species. It would be interesting to compare the overlap of

distribution of this recently introduced species with that of

waterhyacinth. I collected nymphs of this species only be-

tween June and Decemtber.

19 Pachyd~iplax longipennis (Burmeister)--111 specimens

in 30 collections from 15 locations in 8 counties.

Collections: 2, 4, 7, 13, 29, 30, 31, 35, 36, 38, 42,

4-5, 4~7, 51, 53, 54, 56, 57, 6s9, 70, 75, 79, 83, 85, 87, 88,

94, 95, 97, 103.

H aximum density: .391/plant at #51; 37.5/m2 at #85.

!Jater quality preference: iron, r=.900, p=.014, n=6.

Insect- associations: Pelocoris femoratus, r=-.554,

p=.050), n=13.

While not overly abundant at any location, this species

w~as wJidely distributed, and among the odlonates, only Isch-nura

piosita was found in more collections. Among all my specimens,

P. 10n~gagenngs ranked seventh in the number of collections in

which it was found and eleventh in overall abundance. Nymphs

were collected throughout the year, usually at locations

which had a high iron content and harbored low populations of

Pelocoris femoratus. Not surprisingly, both O'Hara (1961) and

Katz (1967) report this species from their waterhyacinth col-


20. Perithemis tenera (Say)--1 specimen collected at

Lake Lawne in Orlando on 13 July 1973.

Collection: 26.

Density: .033/plant.


Frequently considered as a subfamily of the family

Libellulidae, nymphs of this family are bottom sprawlers

and were infrequent in my collection.

21. Mlacromia taeniolata Rambur--2 specimens from 2

collections in 2 counties.

Collections: 102, 103.

Maximum density: .062/plant or 5/m2 at #102.

Both specimens were found in mid-December.

Hemiptera (True Bugs)--Adults and Nymphs

While aquatic hemipterans, with 504 specimens, com-

prised only 9.2% of my total specimens, they represent 10

different families and at least 22 species. The contribu-

tion of aquatic Hemiptera to the diversity (at least the

richness component of diversity) of a collection was rela-

tively great. Only the aquatic beetles and Diptera could

equal the large number of different families in my collec-

tions. While sometimes locally abundant, they were usually

sparsely distributed.

O'Hara (1961) reported only 2 kinds of aquatic Hemiptera:

Belostomatidae and Naucoridae. Katz (1967) lists 9 families

and 10 genera of aquatic H~emiptera, with Notonecta sp. the

only one which I did not also collect.

Since all aquatic HIemiptera (except the Corixidae) are

predaceous, their presence should be associated with that of

a suitable prey organism, most probably the amphipod Hyalella


Belostomatidae (Giant W~ater Bugs)

H~ith 82 specimens, the 3 species of Belostomatidae com-

prised 16.3% of the total Hemiptera collected and were my

second most abundant hemipteran family. They were usually

not particularly abundant at any one site, averaging less

than 4 specimens whenever found. However, they did consti-

tute 26.6%/ of the 60 specimens in collection #54. Both O'Hara

(1961) and Katz (1967) as well as Hansen et al. (1971) men-

tion collecting Belostoma spp. in waterhyacinth roots.

22. Belostoma lutarium (Stal)--12 specimens in 11 col-

lections from 4 locations in 3 counties.

Collections: 18, 36, 70, 71, 72, 75, 88, 94, 95, 96,


Maximum density: .18/plant or 10/m2 at #J94.

Adults of this species were never abundant, more than

one specimen being collected only once. My specimens were

all collected between May and December.

This species was strongly correlated with all the

diversity indices except Simpson's index. The Shannon-

Weaver index for collections in which this species was found

averaged at a relatively high 2.26. The presence of this

species might be used as an indicator of high diversity of

insect fauna in w~aterhyacinth- covered wa~iers.

23. Belostoma testaceum (Leidy)--17 specimens in 10

collections at 5 locations in 2 counties.

Collections: 7, 11, 19, 22, 33, 37, 40, 54, 90, 94.

Maximum density: .333/plant at #137, 10/m2 at #94.

Most of my specimens (65%) came from a drainage culvert

along Interstate 75 north of MZicanopy. Except for 2 speci-

mens found in February, all were collected from June through

Nlovelb er .

Belostoma spp. nymphs--52 specimens in 16 collections

at 5 locations in 3 counties.

Collections: 3, 22, 33, 35, 52, 54, 57, 71, 75, 78, 79,

86, 88, 89, 91, 92.

H~aximum dlensity: .83j/plant at #i22; 15/m2 at #75.

Insect associations: Ischnura posita, r=.779, p=.008,

n=10; Chironomus attenuatus Walker, r=-.661, p=.052, n=9.

Since only the adults of this genus could accurately

be placed at species level, all nymphs of the genera were

placed in this category. Nymphs were collected from Febru-

ary through October.

24r. Lethocerus uhleri (Montandon)--1 specimen col-

lected at Camps Canal in October 1973.

Collection: 35.

Density: .031/plant.

Corixidae (1Jater Boatmen)

All specimens were collected at Otter Creek, Levy Co.,

in July of 1973.

Collections: 20, 21.

Maximum density: .154/plant at #"21.

While the 2 adults appear to be Trichorixa sp., the

other specimen is a nymph and cannot be keyed. Members of

this family are rare among waterbyacinths and were all col-

lected at one location. They were not reported by either

O'Hara (1961) or Kiatz (1967).

Gerridae (Water Striders)

These surface-film forms were rare in my collections.

Although present at the collection sites, they generally

seem to prefer more open water than that found between water-

hyacinth plants. Only a total of 6 specimens of this family

were collected.

26. Gerris canaliculau (Say)--only 1 specimen col-

lected at a small stream near Gainesville in August 1974.

Collection: 87.

Density: .05/plant or 2.5/m2

27. Limnogionus hesione (Kirkaldy)--only 1 specimen

collected at Otter Creek in Levy Co. in July of 1973.

Collection: 21.

Density: .977/plant.

Katz (1967) reports collecting Liminogonus sp. in water-

hyacinth roots.

28. Trepobates sp.--only 1 specimens collected with

L. hesione (above).

Collection: 21.

Density: .977/plant.

Unidentified gierrid nymphs--3 specimens from 3 locations

in 2 counties.

Collections: 20, 38, 75.

Maximum density: .045/plant at #~38 and 2.5/m2 at #75.

Hebridae (Velvet Wjater Bugs)

These small insects, less than 2.5mm long, are incon-

spicuous and frequently overlooked since, unless they are

moving, they appear to be pieces of debris. A total of 21

specimens in 4 species were collected, all of them in Alachua

Co. Katz (1967) records Hebrus sp. from waterhyacinths in

the Withlacoochee River.

29. Hebrus burmeisteri (L. & S.)--4 specimens from 3

locations in Alachiua Co.

Collections: 30, 54, 72.

Maximum density: .971/plant at #~54; 1.0/m2 at #72.

30. H~ebrus consolidus Uhler--5 specimens from 5 loca-

tions in Alachua Co.

Collections: 15, 16, 49, 54, 70.

H~aximum density: .048/plant at #4-9; 1.67/m2 at #70.

All my specimens of this species were collected between

January and July.

31. Merragataa brevis Champion--only 1 specimen from

Camps Canal in Mlay of 1974.

Collection: 70.

Density: .014/plant or 1.66/m2

32. Mlerragata brunnea Drake--11 specimens in 4 collec-

tions from 3 locations in Alachua Co.

Collections: 15, 29, 75, 85.

Maximum density: .083/plant at #15, 7.5/m2 at #85.

All my specimens of this species were collected during

the summer months.

Hydrometridae (HJater Measurers)

With only 18 specimens distributed between 2 species,

this family was never particularly abundant. Katz (1967) re-

ports finding them in 2 of her collections.

33. Hydrometra myvrae Bueno--11 specimens from 7 collec-

tions, all at Camps Canal.

Collections: 31, 69, 70, 72, 73, 95, 99.

Maximum density: .235/plant or 20/m2 at #99.

MIy most common hydrometrid, II. myrae is considered

"... the most prevalent Hydroetra~ in the state" (H~erring 1948,

p.113). My specimens were collected between April and Novem-
ber .

34. Ilydromtr wilevi Hungerford--3 specimens in 2 col-

lections from 2 counties.

Collections: 27, 107.

Maximum density: .125/plant or 10/m2 at #126.

Herring (1948) records this species from only one site

in the state. My records add 2 new counties to the distribu-

tion of this species.

Hydrometra sp. nymphs--4 specimens from 4 collections
at 4 locations in 3 counties.

Collections: 1, 2, 21, 47.

Mlaximumn density: .077/plant at #;21.

H~esoveliidae (Ndater Treaders)

Never very abundant and with only 59 specimens, meso-

veliids were found in 30 of my collections, making them the

second best hemipteran family for representation in differ-

ent collections. Katz (1967) also collected some Mesovelia

in wsaterhya cinths .

35. Hlesovelia mulsanti White--15 specimens in 10 col-

lections from 7 locations in 4 counties.

Collections: 5, 17, 54, 70, 75, 85, 88, 94, 96, 100.

H~aximum density: .091/plant at #94, 10/m2 at #185.

All the adult mesoveliids I collected belonged to this

species. Hterringi (1951b,) records this species from

wa~terhyac inth~s. There is a strong correlation with root

length (r=.813, p=.008, n=9) and high root:shoot ratio

(r=.807, p=.009, n=9) for this species. Adults were col-

lected in February and May through April.

MIesovelia sp. nymphs--44 specimens in 23 collections

at 10 locations in 4 counties.

Collections: 1, 2, 11, 41, 21, 22, 23, 24, 33, 36, 38,

49, 53, 70, 72, 73, 78, 89, 91, 93, 94, 95, 96.

Maximum density: .227/plant at d38; 15/m2 at #95.

Insect associations: yxi~osagu spp., r=-.746, p=.013,


Although all mesoveliid nymphs key out to M. amoena

Uhler, I classed all these nymphs simply as Mlesovelia sp.

Dr. Jon Herring at the National Museum considered most (if

not all1) of my mesoveliid nymphs to be HI. amoena, but I con-

sider this unlikely since I collected no0 M. amoena adults

but many N. mulsanti adults. There is a strong, positive cor-

relation with the presence of stratiomyid larvae, M~yxosargus.

These nymphs were collected throughout th-e year.

Hlaucoridae (Creeping Water Bues)

Inaucorids wJere not only the best-represented hemipteran

family,, being present inl 43 collections, b~ut it was also the

most numerous hemipteran family, with 194 specimens making up

38.53: of hemipterans collected and 3.5% of the total insects.

Bothi O'Hara (1961) andi Katz; (1967) recordl this family, which

is Irepresenited in the eastern Ui. S. by 1 genus and 3 species.

36. Pelocoris balius La Rivers--107 specimens from 31

collections at 9 locations in 3 counties.

Collections: 7, 11, 14, 15, 17, 19, 23, 24, 31, 32,

35, 36, 38, 39, 42, 50, 55, 56, 69, 70, 71, 72, 73, 75, 76,

89, 91, 94, 95, 97, 99.

Maximum density: .405/plant at #35; 16/m2 at #72.

Water quality preference: potassium, r=-.739, p=.009,


Insect associations: Pelocoris femoratus, r=.490, p=.047,

n=17; Hydrovatus larvae, r=.881, p=.048, n=5; Suphisellus in-

sularis (Sharp), r=-.549, p=.052, n=13; Suphisellus puncticol-

lis Crotch, r=.816, p=.048, n=6.

Considered as a subspecies of P. femoratus by La Rivers,

P. balius has been elevated to species rank by me since the 2

species were collected together 17 times.

P. balius is associated with low levels of potassium,

with P. femoratus, Hydrovatus larvae, and with Suphisellus

puncticallis. It is generally found in waters where the num-

bers of S. in~sularis are low. It was collected throughout

the year, with over 79% of the specimens coming from Camps


37. Pelocoris ~femoratus (Palisot-Beauvois)--87 speci-

mens in 29 collections from 8 locations in 2 counties.

Collections: 3, 11, 31. 35, 38, 40, 42, 50, 53, 55, 56,

69, 70, 71, 72, 73, 74, 75, 78, 81, 83, 85, 86, 88, 89, 93,

95, 09, 102.

Maximum density: .205/plant or 25/m2 at #70.

Insect associations: 1schnura p~osit, r=.806, p=.0001,

n=22; Pachydiplax longipennis, r=-.554, p=.050, n=13; Peloc-

oris balius, r=.471, p=.057, n=17; Ranatra australis Hunger-

ford, r=-.920, p=.010, n=6.

This species also was collected throughout the year,

frequently along with P. balius, with which it is marginally

correlated. There is an extremely significant correlation

(p=.0001) with the damselfly nymph Ischnura posita, with P.

femora~tus being found only 7 times (out of 29) in the absence

of I. Roita P. femoratus is negatively correlated with the

anisapteran Pachydiplax 10ngipennis and with the nepid Ranatra

australis. There is a strong correlation (r=-.601, p=.01,

n=17) with plants having fewer leaves. Over 83% of the speci-

mens were collected at Camps Canal.

Nepidae (Nater Scorpions)

With 52 specimens in 9 collections, the 3 species of

water scorpions collected made up only 10.3% of the hemip-

terans collected and less than 1% of the total specimens.

Hlowvever, th~ey were sometimes extremely abundant locally,

with collection #75 averaging 75 specimens/m2. Neither O'Hara

(1961) nor Katz (1967) records any water scorpions from their


38. R~anatra australis Hungerford--35 specimens in 10

collections from 4 locations in 3 counties.

Collections : 3, 17, 73, 75, 76, 94, 95, 99, 102, 103.

Maximum density: .486/plant or 75/m2 at #75.

Water quality preference: nitrates, r=.747, p=.033,


Insect associations: Ischnura posi~ta, r=-.774, p=.041,

n=7; Pelocoris femoratus, r=-.920, p=.010, n=6.

Herring (1951a) records this ". . the most prevalent

Ranatra in Florida" (p. 18) fromt waterhyacinths. This species

was gJenerally found in shallow water which was high in nitrates.

It is negatively associated with the presence of either I.

posita or P. femnoratus. Almost 43% of my specimens were col-

Tected at one time at Prairie Creek in DeSoto Co. Of the re-

maining specimens, 80% came from Camps Canal. My specimens

were all collected from May through December.

39. Ranatra buenoi Hungerford--6 specimens collected

only at Camps Canal, Alachua Co.

Collections: 70, 73, 94, 95.

Maximum density: .20/plant or 15/m2 at #95.

This relatively rare species was collected only at

Camps Canal in May, October, and November.

40. R~anatra nigr Herrich-Schaeffer--11 specimens from

2 collections in 2 counties.

Collections: 102, 103.

Maximum density: .625/plant or 50/m2 at #~102.

Although it was collected only in December at 2 loca-

tions in South~ Florida, it was quite abunldant at Prairie

Creek, averaging 50 water scorpions per square meter.

Pleidae (PygmY Back Swimmers)

Although members of this family, which is represented

by a single species in the U. S., prefer dense, tangled vege-

tation, they were never common in my collections.

41. Ifeoplea seriola (Fieber)--22 specimens in 9 col-

lections from 4 locations from 2 counties.

Collections: 3, 18, 36, 53, 71, 75, 87, 88, 97.

Mlaximumn density: .50/plant: or 25/m2 at #97.

Water quality preference: potassium, r=.910, p=.032,


Formerly known as Plea striola, this species was assoc-

iated with waters high in potassium and having a low Simp-

son's diversity index, with 59% coming from Lake Alice. Katz

(1967) recorded this species from 2 of her collections. Al-

thiough they were found throughout the year, 64% of the speci-

mens were collected during the summer months.

Veliidae (Broad-Shouldered Water Striders)

With 47 specimens distributed between 2 species, this

family was never common, averaging less than 2 specimens

when found, but it was well-represented, being present in

over 30% of my collections. Thus, although they comprise

less than 1% of the total insects collected, their contribu-

tion to the diversity of the collection is important.

42. M~icrovelia borealis Bueno--25 specimens in 15 col-

lections from 12 locations in 4I counties.

Collections : 1, 2, 15, 16, 19, 21, 23, 24, 25, 34, 43,

44, 53, 72, 75.


Hlaximum density: .095i/plant at #16h; 2.5/m2 at #~75.

Katz (1967) recorded this genus in her collections.

43. Velia brachialis Stal--22 specimens in 13 collec-

tions from 5 locations in 4 counties.

Collections: 17, 18, 21, 31, 35, 38, 42, 50, 87, 90,

95, 102, 103.

Maxirmum density: .182/plant at #138; 10/m2 at #103.

Velia is negatively correlated with number of leaves

per plant (r=-.933, p=.020, n=5).

Almost 73% of the specimens came from Camps Canal. Katz

(1967) reports this genus from her collections.

Trichoptera (Caddisflies) Larvae

Only 16 caddisfly larvae belonging to 2 species were

found during this study anid 15 of these came from the same

location. Although from m~y collections Tlrichoptera would

appear to be rare, O'Hiara (1961) reports a probable 3 differ-

ent, unidentified species while Katz (1967) recorded 5 dif-

feren~t groups in her survey.


44. 0ecotis prob. cinerascens (Hagi.)--6 specimens in 4

collections from 2 locations in Alachua Co.

Collections: 3, 35, 50, 87.

Hlaximum density: .05/plant or 2.5/m2 at #87.

All but one of my specimens came from Camps Canal and

all were collected in August and September except for one

specimen collected in January.


45. Polycentropus spp. larvae--10 specimens in 7 col-

lections, all from Camps Canal.

Collections: 70, 72, 74, 76, 80, 82, 91.

Maximum density: .059/plant at #82; 4/m2 at #7;4.

Insect associations: Chironomus attenuatus, r=-.873,

p=.054, n=5.

All my specimens were collected between May and Septem-

ber at Camps Canal. Katz (1967) recorded this genus from

all her collections.


A total of 17 specimens, all belonging to the same

species, were collected. I have found no references for any-

one reporting this group from waterbyacinths.


46. Chauliodes rasticornis Rambur--17 specimens from

10 collections at 2 locations in Alachua Co.

Collections: 11, 42, 69, 70, 72, 73, 74, 89, 91, 95.

Maximum density: .059/plant at #:92; 10/m2 at #69.

WaJter quality preference: nitrates, r=-.697, p=.055,


The larvae of this species can be identified by the

yellow stripe on trhe dorsulm, as noted by Cuyler (1958). The

larvae I collected were correlated with low levels of nitrates

in the w~ater. All but one specimen came from Camps Canal.

Coleoptora (Beetles)

With 2,498 specimens (45.5%/ of the total specimens),

the beetles were my most abundant order and were also the

best represented, being found in all but 3 of my collections.

Collections averaged 33.9 beetles and beetle larvae per col-

lection (excluding the 3 beetle-less collections) At least

64 different species belonging to 42 genera and 10 aquatic

families were present. Of the 2,498 beetle specimens, 14.8%

were larvae. Most beetle larvae could be identified only

to genus except when the genus was monotypic.

O'Hara (1961) reports the following beetles from his

waterhyacinth root collection: Dytiscidae, Omophronidae,

Haliplidae, Gyrinidae, Carabidae and Hydrophilidae. Carabi-

dae, of which he had only one specimen, are not considered

aquatic. Omophronidae, whJlich are considered part of Carabi-

dae by some authorities, have not been reported frequently

from Florida and are semi-aquatic, living in the moist soil

of riverbanks and lakes. I believe, since these were his

most common beetles (and I collected none), that he probably

has misidentified a noterid such as Colpius inflatus or a

dytiscid such as Hiydrovatus sp.

Katz (1967) presents 45 different genera of beetles.

At least 10 of her genera, however, belong to families such

aIs Alnthicidae, Curculionidiae, Scaphidiidae, Scolytidae and

Staphylinidae. which are not known to have truly aquatic mem-

bers in Florida. By truly aquatic, I mean insects which have

at least one life stage in or on the water. She also lists

Limnichus sp., which is only known from southwestern U. S.,

and Heogors which has not, to my knowledge, been other-

wise recorded from Florida.

Dryopidae (Long-Toed Water Beetles)

With only 3 specimens of one species, dryopids were

relatively rare in waterhyacinth roots. Since they are

usually found in riffle areas of small, rapid streams, few

would be expected in the lentic situations in which water-

hyacinths are found.

47. Pe~olonm obscurus gracilipes Chevrolat--3 speci-

mens from 3 collections at Camps Canal, Alachua Co.

Collections: 89, 91, 94.

Maximum density: .091/plant or 5/m2 at #94.

Katz (1967) reports collecting Pelonomus sp.

Dytiscidae (Predaceous Water Beetles)

WJith 752 specimens, the dytiscids, along with the

Coenagrionidae, were tied for third most abundant family,

preceded only by the noterids with 1,432 specimens and the

chironomids with 1,046 specimens. At least 30 different

species of dytiscids were collected, by far surpassing the

16 species of chironomids, which ranked second in terms of

number of species per family. Thus, the contribution of

dytiscids to the diversity of the sysLem w~as very great,

especially since they comprised only 13.7% of the total

specimens collected and 30.11/ of the beetles collected.

Of the dytiscid subfamilies, the H-ydroporinae are

definitely a characteristic component of waterhyacinth root

beetle fauna. The Hydroporinae comprised 89.6% of my dytis-

cid specimens and of the 12 genera known from Florida, I

collected 10.

Of the dytiscid specimens, 132 (17.6%) were larvae. Of

the beetle families, only the helodids had more larvae.

Katz, (1967) lists the following dytiscid genera from her

waterbyacinth root collections: Bidessus, Laccodytes, Hydro-

vatus, Laccophilus, Orcodytes (=Hydro orus i at) eia

Cogelatus, Derovatellus, Hygrrotus, Coptotomus and Cybister.

Of these genera I collected all but Laccodytes, Derovatellus

and ~1gygots O'HIara (1961) found no dytiscid larvae and
found adults were relatively rare.

48. Anodochiilus exiguus (Aube)--1 specimen collected at

Otter Creek, Levy Co., inl July.

Collection: 21.

Density: .077/plant.

49. Bidessonotus longavalis (Blatchley)--1 specimen

collected at Camps Canal, Alachua Co., in July.

Collection: 18.

50. Bidessonotus pulicarius (Aube)--7 specimens in 5

collections at 2 locations in Allachua Co.

Collections: 36, 75, 93, 94, 95.

M-aximumn density: .182/plant or 10/m2 at #~94.

Five of my specimens were collected in October while

one each were found in June and November.

Bidessonotus spp. females--4 specimens in 4 collections.

Collections : 2, 34, 71, 74.

Maximum density: .026/plant or 5/m12 at #71.

Since some species of Bidessonotus can be identified

only by the shape of the aedeagus, some unidentifiable fe-

males of the genera are placed in this classification.

51. Bidessus flavicollis (LeConte)--4 specimens in 2

collections in Alachua and Orange Cos.

Collections: 3, 96.

M~aximumn density: .15/plant or 15/m2 at #96.

My specimens were collected in August and November.

This species is usually found in algal mats.

52. Brachyvatus seminulus (LeConte)--79 specimens in

10 collections from 6 locations in 2 counties.

Collections: 3, 25, 35, 71, 75, 79, 85, 87, 88, 94.

Maximum density: 1.163/plant or 142.5/m2 at #85.

Insect associations: Telebasis bversi, r=-.918, p=.028,


This genus was once considered as a subgenus of Bidessus.

A single collection at the Styx River in August accounted for

72% of my specimens of this species, which reached a density

of over 140 per square meter. All of m~y specimens were col-

lected from May through October, with the majority (85%)

being collected in August.

53. Ce~lina anustata Aube--6 specimens in 5 collections

from 5 locations in 3 counties.

Collections: 15, 19, 29, 77, 79.

Maximum density: .133/plant and 5/m2 at #~77 and #79.

All my specimens were collected in June or July.

54. Celina grossula LeConte--19 specimens in 10 col-

lections from 6 locations in 2 counties.

Collections: 13, 15, 23, 30, 44, 80, 81, 89, 91, 92.

Maximum density: 3.84/plant or 25/m2 at #92.

Insect associations: Colpius inflatus (LeConte),

r=-.934, p=.020, n=5.

This species was significantly negatively correlated

with almost all the measures of diversity, indicating that

it is generally found in low diversity locations. All my

specimens were collected June through September except 2

collected in December in South Florida.

55. Celina slossonni Mlutchler--3 specimens from 3 loca-

tions in Alachua Co.

Collections: 29, 34, 92.

Maximum density: .077/plant or 5/m2 at #~92.

COLlected in July, September and October.

Celina spp. larvae--44 specimens in 22 collections from

9 locations in 2 counties.

Collections: 12, 13, 19, 22, 24, 26, 29, 32, 34, 36,

37, 39, 52, 53, 54, 73, 81, 82, 85, 86. 89, 91.

Maximum density: .333/plant at #37, 15/m2 at #86.

Insect associations: Hydrocanthus larvae, r=.840,

p=.009, n=8; P'oyp~e~dilm illinoense (Mlalloch), r=.878,

p=.021. n=6.

My second most abundant beetle larvae, Celina larvae

were found in more different collections than any other

beetle larvae.

Celina spp. larvae were collected throughout the year

but appear to be most commIon during late summer and fall.

These larvae were found to be strongly associated with a

dytiscid larva and significantly associated with a chiro-

nomid larva.

56. Copelatus caelatipennis princeps Young--11 speci-

mens in 8 collections from 5 locations in 2 counties.

Collections: 1, 3, 7, 37, 52, 74, 81, 89.

Maximum density: 1.667/plant at #37; 3.33/m2 at #8s9.

All my specimens of this species were collected from

June through October except for one specimen collected at

Lake Alice in February.

57. Copeflatus chevrolati chevrolati Aube--13 specimens

in 5 collections from 3 locations in 2 counties.

Collections: 1, 21, 42, 93, 94.

Maximum density: .183/plant or 10/m2 at #194.

Found from July through December, this species is known

to prefer areas with accumulations of organic debris.

58. Coptotomus inppyoggyp g obscurus Sharp--3 specimens

froml 3 locations in 2 counties.

Collections: 17, 27, 103.

Maximum density: .032/plant or 5/m2 at #~103.

Both of my Alachua Co. specimens w~ere collected in July

while the one from South Florida was found in December.

59. Cybister frimlbiolatus crotchi Wilks.--1 specimen

from a drainage ditch in Alachua Co. in February.

Collection: 54.

Density: .036/plant.

While only a single adult of this species was collected,

11 larvae were found. This may indicate that the larvae are

most attracted to waterhyacinth roots or perhaps that the

adults, among the largest of Florida's water beetles, were

able to elude capture.

Cybister sp. larvae--11 specimens in 7 collections from
6 locations in 3 counties.

Collections: 33, 47, 75, 78, 85, 88, 99.

Maximum density: .073/plant: or 7.5/m2 at #~75.

Cybister sp. larvae were collected from June through

December with most (45.4%/) being found in June.

60. Desmopachria grana (LeConte) complex--27 specimens

in 16 collections from 11 locations in Alachua Co.

Collections: 1, 11, 14, 15, 19, 23, 27, 34, 37, 39, 41,

52, 57, 91, 94, 95.

MIaximum density: .654/plant or 25/m2 at #94.

Insect associations: My~xosargus sp., r=.845, p=.034,


This small dytiscid, characteristic of detritus pond

condiitions, w~as well-distributed throughout Alachua Co.,

being present at 11 of the 16 different areas I collected.

I collected this species throughout most of the year, with

the exception of the spring months. It w~as most abundant in

myr October collections, with 38% of the total Desmopachria

61. Ilydroporus dix~ianus Fall--2 specimens collected

together at Lake Talquin, Gadsden Co.
Collection: 95.

Density: .1/plant or 10/mn2

Only one other specimen of this rare species has been

recorded from Florida (Young 1955).

62. Hy~droou lobatus Sharp--ll specimens from 6 col-

lections at 3 locations in Alachua Co.

Collections: 17, 18, 51, 74, 76, 83.

Maximum density: .087/plant at #51; 5/m2 at #83.

Of my specimens, 10 were collected during the summer and

one in Jaunary. Most (73%) were collected at Camps Canal in

Alachua Co.

63. Hydroporus lynceus Sharp--1 specimen collected in

November at Lake Talquin, G~adsden Co.

Collection: 96.

Density: .05/plant or 5/m2

64. Hiydroporus v~ittatipennis Gemminger & Von Harold--

1 specimen collected in November at Lake Talquin, Gadsden Co.
Collection: 95.

Density: .05/plant or 5/m2

65. Hlydrovatus compr~essus Sharp--276 specimens in 36

collections from 15 locations in 6 counties.

Collections : 12, 23, 24, 25, 26, 29, 30, 32, 33, 36, 37,

39, 41, 44, 46, 49, 52, 55, 57, 71, 75, 76, 78, 79, 80, 81,

83, 84, 85, 86, 88, 89, 91, 92, 93, 97.

Maximum density: 1.095/plant at #~49; 110/m2 at #~71.

Water quality preferences: sulphur, r=.785, p=.021, n=8;

magnesium, r=.604, p=.010, n=17; sodium, r=.554, p=.021, n=17.

Insect associations: Suphisellus insularis (Sharp),

r=.548, p=.006, n=24.

This species was extremely well represented, being found

in 41% of my collections. Only one species, the damselfly

Ischnura posita, was found in more collections. In sheer

numbers, it was my most common dytiscid, my second most abun-

dant beetle, and fifth in abundance out of all the species.

Comprising 36.7% of the dytiscids collected, this beetle has

significant correlation coefficients indicating that it occurs

most commonly in waters that have relatively high values of

sulphur, magnesium and sodium. It is negatively correlated

with leaves per plant (r=-.486, p=.048, n=17). It is also

extremely strongly associated with the presence of the noterid

Suphisellus insularis, the only beetle monre abundant than H.

compressus. If one of these species were present, in 67%

of the cases the other would be present also. Lake Alice

accounted for 63.6% of the specimens, whiiLe Camps Canal pro-

vided an additional 17%/. This species was abundant especially

during late w~inter and was collected throughout the year.

66. Hydrovatus inexpec~tatu Young--1 specimen collected

in July at Camps Canal, Alachua Co.

Collection : 80.

Density: .013/plant or 1/m2

This species is very similar to H. compressus and more

specimens may be mixed in with that species. However, Dr.

Frank Young, whio described the species (Young 1963), examined

all my specimens and believes that my determinations are cor-


67. Hydrovatus peninsularis Young--104 specimens in 25

collections from 12 locations in 3 counties.

Collections: 3, 11, 15, 16, 19, 22, 23, 24, 25, 29,

33, 37, 39, 40, 44, 57, 74, 76, 80, 85, 86, 89, 81, 93, 97.

Maximum density: .667/plant at #37; 40/m2 at #86.

Insect associations: Phaenotumn excstriatus Say, r=.781,

p=.013, n=9; Hesonoterus addendus (Blatchley), r=-.837, p=.038,

Accounting for 14% of the dytiscid specimens, this was my

second most abundant and my second best represented species

of dytiscid. Strongly associated with taller waterhyacinth

plants (r=.447, p=.018, n=24), H. peninsularis is also associ-

ated w~ith the presence of the hydrophilid Phaenotum exstria-

tus. The conditions which favor the presence of the noterid

Mesonoteruss addendus would seem to inhibit: the presence of

H. peninsularis. 11. peninsularis appeared to be most abun-

dant in July, during which 30.8% of my specimens were collected.

Hpdrovatus sp. larvae--20 specimens in 12 collections
from 5 locations in 2 counties.

Collections: 23, 27, 30, 39, 41, 44, 71, 74, 87, 94,

95, 97, 99.

Maximum density: .194/plant at #;55, 5/m2 at #~75.

Although Hydrovatus larvae are correlated (r=.912,

p=.031, n=5) with higher water temperatures, they were found

throughout the year.

68. Laccophilus gentilis LeConte--17 specimens in 13

collections from 7 locations in 3 counties.

Collections: 23, 27, 30, 39, 41, 44, 71, 74, 87, 94,

95, 97, 99.

Maximum density: .2/plant or 10/m2 at #97.

Insect associations: Suphisellus insularis, r=-.832,

p=.040, n=6.

Collected from May through December, over half the

specimens were found during the fall. A greater number of

leaves per plant was correlated to this species (r=.823,

p=.023, n=7).

69. Laccophilus proximum Say--14 specimens in 9 col-

lections from 4 locations in 3 counties.

Collections: 38, 45, 75, 91, 92, 94, 95, 101, 102.

Maximum density: .188/plant or 15/m2 at #~102.

Water quality preference. pH, r=.798, p=.031, n=7.

This species seems to prefer waters high in pH. It was

collected from June through December.

LaccoIly lus sp. larvae--4 specimens from 4 locations in

Alachua Co.

Collections: 12, 27, 29, 33.

Maximum density: .062/plant or 3.33/m2 at #:88.

All the Laccophilus larvae were collected during the

summer months.

70. Liodessus affinis (Say)--2 specimens from 2 loca-

tions in 2 counties.

Collections : 18, 4;8.

Maximum density: .026/plan-t at #4-8.

Liodessus was previously considered a subgenus of


71. Liodessus fuscatus (Crotch) -- 1 specimen collected

in July at Otter Creek, Levy Co.

Collection: 20.

Density: .306/plant.

This species is usually associated with sphagnum moss.

72. Matus ovatus blatchleyi Leech--1 specimen collected

in June at a pond in Alachua Co.

Collectioni: 11.

M~atus sp. larvae--2 specimens collected fromi 2 locations

in Alachua Co. during June and July.

Collections: 11, 23.

Maximum density: .017/plant at #23.

73. Neobidessus pullus floridanus (Fall)--1 specimen

from Lake Allice, Alachua Co., in June.

Collection: 75.

Density: .024/plant or 2.5/m'.

This genus was also part of the old genus Bidessus.

74. Pachydrus obniger Chevrolat--3 specimens from col-

lections at a drainage ditchr in Alachua Co.

Collections: 33, 40.

Hiaximum density: .038/plant.

Florida specimens of this species were called P. princeps

(Blatchley), but Dr. F. N. Young (personal communication) does

not believe them to be distinct from the P. obnige from Cuba.

Pachydrus obniger larvae--45 larvae in 18 collections
from 8 locations in 3 counties.

Collections: 14, 24, 29, 33, 37, 52, 71, 74, 75, 78,

79, 83, 84, 86, 89, 91, 93, 94.

H~aximum density: .469/plant or 25/m2 at #89.

Water quality preference: iron, r=.912, p=.031, n=5.

BLatchley (1914) recorded this species (as P. princeps,

a new species) from beneath dead waterbyacinths along the

shore of Lake Okeechobee.

Insect associations: Hydrovatus Eeninsularis, r=.681,

p=.043, n=9; Phaenotumr exstriatus, r=.875, p=.010, n=7;

Suphisellus g~ibbulus (Aube), r=.744, p=.021, n=9; M~yxosargus

sp., r=.889, p=.017, n=6.

Pachydrus larvae were found in waters having high iron

content and -frequently havinge populations of the dytiscid H~.

peninsularis, the hydrophilid P. exstriatus, the noterid S.

gibutus, and the stratiomyid Myxasargus. Over 55% of the

specimens came from Camps Canal, and all but 2 specimens were

collected between May and October.

75. Thermonoctuls basillaris (H~arris)--1 specimen col-

lected in July at a drainlage- ditch in Alachua Co.

Collection: 22.

Density: .055/plant.

76. Uvarus falli (Young)--1 specimen collected in July

at Otter Creek, Levy Co.

Collection: 21.

Density: .077/plant.

This species is thought to be restricted to sand-

bottomed streams such as Otter Creek.

Unidentifiable Bidessini larvae--10 larvae in 7 collec-

tions from 4 locations in Alachua Co.

Collections: 19, 24, 25, 49, 52, 86, 91.

Maximum density: .143/plant at #~49; 5/m2 at #86.

Some dytiscid larvae could be identified only to the

tribe level. The tribe Bidessini has 5 g~enera: Bidessus

(sensu latu), Bidessonotus, Brachyvatus, Desmopachria and

Pachvdrus .

Elmidae (Riffle Beetles)

It is not surprising that I collected only 3 specimens

from this family since its members are usually restricted to

riffle areas of streams. Katz (1967) found 3 genera of

elmids in her waterbyacinth root collections.

77. Dubiraphia quadrinotata (Say)--3 specimens in 2

collections from 2 counties.

Collections: 18, 103.

Maximum density: .032/plant: or 5/m2 at #~103.

Gyrinidae (Whirligig Beetles)

Only 3 specimens from 3 different species were collected

from w~aterhyacinth roots. While members of this family were

frequently present at the collecting site, they seem to pre-

fer patches of open water larger than that found between

waterhyacinth plants in a mat. O'Hara (1961) reports col-

lecting gyrinid larvae but no adults. Katz (1967) records

one genus of gyrinid but does not distinguish whether larvae

or adults or both were found.

78. Dineutes sp. larvae--1 specimen at Otter Creek,

Levy Co., in July.

Collection: 21.

Density: .077/plant.

Katz (1967) reports this genus from several of her col-


79. Gyrinus elevatus LeConte--single specimen collected

at Peace River, Hardee Co., in December.

Collection: 102.

Density: .063/plant or 5/m2

80. Gvrinus woodruf~fi Fall--single specimen collected

in October at Camps Canal, Alachua Co.

Collection: 35.

Density: .031/plant.

This species is considered to be primarily a stream

species, thus it would not be expected in the lentic habitats

that waterbvacinths refer.

Halip~lidae (Crawling Water Beetles)

Only 12 specimens in 3 different species in one genus

were found. While not common, they were not truly rare in

waterbyacinth roots. Since adults crawl and swim along the

bottom, they probably only occasionally hide in waterhyacinth

roots. Katz (1967) recorded Peltodyte sp. from 2 of her

collections. O'Hara (1968) found haliplids locally abundant

but recorded only the genus HIaliplus, which was not collected

either by Katz or myself.

81. Peltodytes dietrichi Young--3 specimens in a single

collection in July from Otter Creek, Levy Co.

Collection: 21.

Density: .231/plant.

This recently described species (Young 1961) was col-

lected only once.

82. Pel~todvtes floridecnsis Mlathesonl--G specimens from

3 collections at 2 locations in 2 counties.

Collections: 20, 21, 87.

Maximum density: .385/plant at #:21; 2.5/m2 at #87.

83. Peltodytes o~ppoiu Roberts--3 specimens from 3
locations in 2 counties.

Collections: 38, 71, 102.

Maximum density: .063/plant or 5/m2 at #102.

Hlelodidae (=Cyphionidae) (Ma~rsh Beetles) Larvae

The Helodidae, somnetimies also ktnownm as the Cyphonidae,

consisted of 138 Jarvae belonging to 2 genera and at least

3 species. In older literature, usually considered a part

of Dascillidae, the American helodid fauna is very poorly

known, with the best key to the species of adults being al-

most 100 years old (Horn 1880). Existing keys to larvae,

such as Leech and Chandler (1968), do not include all the

genera. My specimens were identified by rearing the larvae

and comparing the adults to old species descriptions and

identified material at The F~lorida State Collection of

Arthropods. While the adults enter the water only for ovi-

position or escape, the larvae were sometimes abundant in

closely packed, detritus-filled mats of wYaterbyacinths.

Katz (1967) collected specimens from this family but reports

Cyglgon, a genus which I did not find, and does not mention

the genera I collected.

84. Ora hvacintha Blatchley (adults reared from lar-

vae)--3 specimens reared from larvae from 2 collections at

a drainage ditch, Alachua Co.

Collections: 33, 37.

Maximum density: .333/plant.

Described by Blatchley in 1914 from adults found among

dead waterbyacinths on the shore, this species could be dis-

tinguished from my other species of Ora only in the adult

stage. The species name seems especially appropriate in

viewJ of the abundance of what are probably larvae of this

species in some waterbyacinth habitats.

85. Ora troberti (Guer.) (adults roared from larvae)--

3 specimens from 2 locations at a drainlage ditch in Alachua

Collections: 33, 37.

Maximum density: .333/plant.

The adults of this species were also obtained from

rearing collected larvae. While my specimens appear to fit

the description for this species, they may represent another

similar, yet undescribeed species.

Ora sp. larvae--90 specimens from 8 collections at a

drainage ditch in Alachua Co.

Collections: 22, 33, 37, 40, 43, 51, 54, 57.

Maximum density: .879/plant.

I could not distinguish the larvae OE 0. hyacinth

from the larvae of 0. trobert-i due to the overlap of almost

all characteristics studied. All Ora larvae were lumped to-

gether; even though the largest larvae were almost surely

0. Igacnta the smaller larvae could be either species.

Ora sp. larvae were associated with waterhyacinths growing

in deeper water. All my Ora larvae came from the same loca-

tion, a drainage ditch off of I-75 north of Micanopy in

Alachua Co., where they were the most frequently collected

and second most numerous insects found. All but 10 speci-

mens were collected in the fall and early winter months.

86. Scirtes spp. adults--single specimen from drainage

ditch- in Alachua Co. in September.

Collection : 33 .

Density: .019/plant.

A single Scirtes adult was found. Although adults are

not truly aquatic, since thley sometimes enter the water this

specimen was not excluded from my collection.

Scirtes sp. larvae--41 specimens from 13 collections

in 9 locations in 2 counties.

Collections: 11, 12, 13, 14, 51, 22, 33, 51, 54, 75,

89, 90, 97.

Maximum density: .545/plant or 30/m2 at #~90.

Insect associations: Telebasis byersi, r=-.886,

p=.045, n=5.

Scirtes larvae were found at many more different loca-

lions than Ora larvae although not as many specimens were

collected. Unlike the Ora larvae, most were collected

during the summer, although some were found during the winter

also. Scirtes larvae also appear to be associated with

waterhyacinths plants having shorter roots.

Hydraenidae (=Limnebiidae) (M~inute Moss Beetles)

These tiny beetles, less than 14- mm long, were never

abundant in my collections, and their size may have contri-

buted to their being overlooked in some collections. Only

one of the two species known from Florida was found and it

was represented by 12 specimens. Neither O'Hlara (1961) nor

Katz (1967) records any members of this family.

87. Hydraena marginiecllis Kiesenwetter--12 specimens

fromt 7 collections at 5 locations in 2 counties.

Collections: 2, 3, 21, 33, 34, 42, 53.

Maximum density: .15lt/plant.


Considered by many to be a subfamily of the hydro-

philid-s, I felt that Drs. Young, Hellman and others were

justified in considering the hydrochids a separate family.

Only 9 specimens belonging to 4 different species were col-

lected. All were identified by Dr. Hellman of the University

of M~aryland.

88. Hydrochus ainaqualis LeConte--5 specimens from 4

collections at Camps Canal, Alachua Co.

Collections: 38, 53, 91, 94.

Maximum density: .091/plant or 5/m2 a 94

89. Hydrochus prolatus Hellmian--single specimen col-

lected in July at Otter Creek, Levy Co.

Collection: 21.

Density: .077/plant.

90. Hydrochus simplex Leconte--single specimen collected

in July at Otter Creek, Levy Co.

Collection: 21.

Density: .077/plant.

91. Hydrochu woodi Hellman--2 specimens in 1 collec-

tion from Camps Canal in July.

Collection: 17.

Density: .061/plant.

Hydrophilidae (W~ater Scavenger Beetles)

With only 131 specimens, 17 of which were larvae,

hydrophilids were not one of my most abundant families.

While only 3 of the 13 species were represented by 10 or

more individuals, they were fairly well distributed, with

hydrophilids being found in 40 collections. O'Hara (1961)

reports collecting no larvae and that hydrophilid adults

were rare. Of the Hydrophilidae genera listed by Katz (1967)

from waterbyacinth roots, I collected: Paracymus, Enochrus,

Tropisternus, Phaenotum, Berosus, Helobata, Helochares and

Cren-itulus. I additionally collected Cercyon, Derrallus and

Hydrobiomorpha, while she also found Heloghorus and Laccobius.

92. B~erosus exiguus Say--2 specimens collected in July

at Otter Creek, Levy Co.

Collection: 21.

Density: .154/plant.

This species is usually collected from sand-bottomed

streams such as Otter Creek.

93. Cercyon praetextatus Say--single specimen collected

in Miay at Camps Canal, Alachua Co.

Collection: 73.

Density: .008/plant or 1/m2.

94. Crenitulus suturalis (LeConte)--18 adults from 4

collections at 3 locations in 2 counties.

Collections: 1, 21, 22, 33.

Maximum density: .225/plant.

This was my third most numerous hydrophilid, but two-thirds

of my specimens were in collection #:33, with the I-75 drain-

age ditch supplying 78%/ of the specimens. All were collected

from Junie tirouigh July.

Crenitulus suturalis (?!) larvae--1 larva collected in

August at Camps Canal, Alachua Co.

Collection: 89.

Density: .031/plant or 1.66/m2

This larva is different from any of the described

genera from Florida. Since Crenitulus, a monotypic genus,

is the only known genus of hydrophilid from Florida and

whose larva is not known, Dr. Paul Spangler at the Smith-

sonian believes it highly probable that the larva is of

Crenitulus suturalis.

95. Derrallus altus (LeConte) adults--6 specimens in

5 collections from 2 locations in 2 counties.

Collections: 17, 72, 79, 91, 94.

Maximum density: .182/plant or 10/m2 at #94.

Derrallus altus larvae--3 specimens in 3 collections

from 2 locations in Alachua Co.

Collections: 49, 50, 70.

Maximum density: .048/plant at #49; 1.67/m2 at #70.

96. Enochrus blatchleyi (Fall)--2 specimens in 2

collections from a drainage ditch in Alachua Co.

Collections: 40, 51.

Maximum density: .043/plant at #~51.

97. Enochrus ochraceus Melsheimer--29 specimens in 16

collections from 6 locations in 3 counties.

Collections: 3, 18, 30, 33, 41, 42, 43, 45, 70, 71,

86, 89, 91, 94, 95, 98.

Maximum density: .353/plant or 30/m2 at #70.

This species, a detritus pond inhabitant, was my second

most abundant hydrop~hilid and wras tied in the number of col-

lections in which it was found. All my specimens were col-

lected between M~ay and December, with over half coming from

Camps Canal.

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