Title: Florida Entomologist
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Title: Florida Entomologist
Physical Description: Serial
Creator: Florida Entomological Society
Publisher: Florida Entomological Society
Place of Publication: Winter Haven, Fla.
Publication Date: 1943
Copyright Date: 1917
 Subjects
Subject: Florida Entomological Society
Entomology -- Periodicals
Insects -- Florida
Insects -- Florida -- Periodicals
Insects -- Periodicals
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General Note: Eigenfactor: Florida Entomologist: http://www.bioone.org/doi/full/10.1653/024.092.0401
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Volume ID: VID00255
Source Institution: University of Florida
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Florida Entomologist
Official Organ of the Florida Entomological Society

VOL. XXVI JULY, 1943 No. 2

DATA AND OBSERVATIONS ON THE NATURAL REDUC-
TION OF ANOPHELES MOSQUITO LARVAE IN
CERTAIN ENVIRONMENTS
HOMER HIXSON
In considering the factors in nature that prevent mosquitoes
from becoming abnormally abundant, it becomes quite evident
even from superficial observations that many forms of aquatic
life play a significant part. Both plants and animals have been
designated as important in this capacity, but apparently there
is no statistical evidence on the efficiency of predators under
natural conditions. Considerable information has been accu-
mulated, however, based on laboratory study and field observa-
tions made in disturbed environments, but the activity of pred-
ators under such conditions is not a true index of their efficiency
as predators within the range of conditions characterizing nat-
ural environments.
In view of this fact, a study was made in 1938-39 in perma-
nent water basins in the vicinity of Gainesville, Florida in an
attempt to determine the efficiency of biological factors that hold
anopheles mosquitoes in check. Precise evidence, as is to be
expected in this type of study, was foiled not only by the com-
plexity of the environment, but by the cyclic and abrupt changes
that normally occur in water environments, the most significant
of which were temperature, increase and decrease in vegetative
growth, rainfall, rise and fall of the water level, the action of
different predators and factors that influence predator abun-
dance. Never-the-less, the data obtained presents a rather clear-
cut picture of what might be expected to occur in anopheles pop-
ulations in certain ecological associations; and although specific
evidence is obscured, mosquito population data and observations
on the range of activity, aggressiveness and abundance of pred-
ators are considered sufficient to ascertain the principal predators
and give a strong indication as to their efficiency.









THE FLORIDA ENTOMOLOGIST


The forms encountered in this study that were observed to
prey on the active immature stages of anopheles include the fol-
lowing: the mosquito fish (Gambusia affinis), water scavenger
beetle larvae (Tropisternus spp.) 1, the top minnow (Heteran-
dria formosa), a creeping water bug (Pelocoris spp.), a water
measure (Hydrometra spp.), a back swimmer (Plea spp.), and
a water-scorpion (Ranatra spp.).
The mosquito fish is an aggressive, ravenous surface feeding
species which was prevalent throughout the year in and around
vegetation and near the shore line. A definite increase in abun-
dance was noted in mid-April and maintained until mid-June at
which time the number began to diminish rapidly, apparently
through the action of larger predatory fish.
The water scavenger beetle larva is an aggressive ravenous
predator that crawls about just below the surface of water on
submerged vegetation in the immediate range of anopheles lar-
vae which are seized and devoured. This form was noted to
have become numerous on August 12 and on two occasions in the
latter part of August, fourteen specimens were taken in 10 dips;
it was still prevalent in early October.
Other predators that occurred within the range of these
studies were either scarce or their customary range of activity
limited their importance as predators of anopheles. Although
the top minnow was abundant and inhabits the upper strata of
water, it is considered of secondary importance when in an as-
sociation with the mosquito fish because it is less aggressive and
has more of a tendency to remain among submerged vegetation
and feed below the surface of the water. The other species of
lesser importance were comparatively scarce in the environ-
ments studied and for the most part only their range of activity
brought them within the scope of this study.
The greater part of this study was made near the shore of a
small lake which will be referred to as Lake Alice, in an area
exposed to the sun and characterized by a predominating growth
of parrot's feather (M.ri'h phlll ltr proserpinacoides) in the
water usually a few feet beyond the shoreline, sedge (Cyperus
strigosus) and smartweed (Persicaria punctata) growing in the
water at the shoreline, lesser duckweed (Lemna minima) vary-
ing in abundance on the surface of the water among the upright

SDetermined by Frank N. Young, Jr., Biology Department, University
of Florida. Adult Tropisternus specimens collected were identified as T.
lateralis and T. blatchleyi.









VOL. XXVI-No. 2


vegetation; greater duckweed (Spirodela polyrhiza), floating
fern (Azolla caroliniana), and pennywort (Hydrococtyle spp.) 2
occurred within the environs of this study, but were not abun-
dant enough to play a significant part. The predators in this
area included the mosquito fish and top minnow in abundance
and the other predators listed above which occurred only in com-
paratively small numbers. Both Anopheles quadrimaculatus and
A. crucians were breeding in this area; twenty-six per cent of
315 fourth instar anopheles larvae and eighteen percent of 39
pupae were A. quadrimaculatus.
To check against the factors in Lake Alice, data were taken
in a small pond which will be referred to as the permanent pond.
This pond was in an elgonate limestone pit surrounded by pine
and deciduous trees and shaded for the most part. It was ap-
parently fed by seepage and contained water except at short in-
tervals in unusually long dry periods. The fauna in the water
gave evidence of its permanent nature. Considered from the
viewpoint of this study, this pond was characterized by small
patches of a heavy growth of a small upright plant, Globifera
umbrosa, and dense localized growths of Wolffiella floridana; a
comparatively light growth of lesser duckweed and a few plants
of smartweed were present. The heaviest anopheles breeding oc-
curred in the Globifera umbrosa. Both Anopheles quadrimac-
ulatus and A. crucians were breeding in this pond. The predator
incidence was about the same as that in Lake Alice with the ex-
ception that there were no minnows and water scavenger beetle
larvae became very abundant.
The data taken in this study included a separate count of the
anopheles in each active stage in each successful dip of water.
Ten or tweny dips were taken in checking the population and an
effort was made to dip from all types of places within the area.
Checking was timed in an effort to catch each stage at its height
in population within a developmental cycle. Other data taken in-
cluded the temperature of the water and the rise and fall of the
water level. Notes were made on the fluctuation in predator
population, their habits and aggressiveness, and the variations
in the vegetation.
The data presented in Table I, taken in the permanent pond
in the latter part of May, is a type example of data obtained from

Specific determinations of these plants were made by Miss Lillian E.
Arnold and Mr. Erdman West of the Botany Department, University of
Florida.










THE FLORIDA ENTOMOLOGIST


a study made at a time when mosquito breeding and the predator
factor was at low ebb and the temperature of the water was rel-
atively moderate and almost constant, ranging between 25 and
260 C. It will be noted that the total number in each larval stage
increased with each advanced stage and is less in the pupal stage.
This is to be expected because of the fact that a longer time is
required to pass each successive larval stage and a shorter time
is required in the pupal stage; thus, the time factor accounts for
the greater or less accumulation in any particular stage.

TABLE I.-PERIODIC INCIDENCE OF THE DIFFERENT STAGES OF ANOPHELES IN
THE PERMANENT POND IN MAY, 1939.
(10 dips made in each check)
Total
Date Checked 19 24 26 28 Number
Stage Number Collected Collected

First Instar .-.............. 2 3 3 4 12
Second Instar --......... 7 2 6 2 17
Third Instar .................... 7 7 6 4 24
Fourth Instar ................ 3 8 13 7 31
Pupa ..-----.. -------- 0 1 3 4 8


The data presented in Table II, taken in the permanent pond
during August, reveals the effectiveness of water scavenger
beetle larvae in reducing anopheles incidence under certain con-
ditions. The temperature of the water at the time these data
were taken ranged between 25 and 27.5 C.

TABLE II.-PERIODIC INCIDENCE OF THE DIFFERENT STAGES OF ANOPHELES
IN THE PERMANENT POND IN AUGUST, 1939.
(10 dips made in each check)
I I Total
Date Checked 5 9 10 12 13 15 17 19 21 23 Number
Stage Number Collected Collected

First Instar .. 12 56 97 162 114 54 78 94 96 66 829
Second Instar 11 12 22 53 70 92 76 48 80 60 524
Third Instar 13 12 7 16 24 19 78 39 24 24 256
Fourth Instar 5 9 19 9 7 8 17 29 40 11 154
Pupa .......... 0 2 1 6 4 2 1 2 7 11 36









VOL. XXVI-No. 2


This data shows the gradual population build-up in each stage
and the peaks of abundance which came in the first instar be-
tween the 10th and 13th, in the second instar between the 13th
and 17th, in the third instar between the 15th and 19th, in the
fourth instar between the 19th and 23rd, and the peak of pupal
incidence occurred between the 21st and 23rd. The sum of the
three figures within the peak range of each stage corresponds in
ratio almost exactly in every instance with the percent popula-
tion decrease indicated in the total column. Without account-
ing for the developmental time factor which on the basis of the
data in Table I would account for an increase of 11% in preda-
tory evaluation in this case, this data indicates an 81% decrease
during larval development with a marked reduction in each
stage. Never-the-less, the biotic potential under these conditions
was high enough to overcome this increased natural resistance as
indicated by the number of mosquitoes reaching the pupal stage.
This series of data was terminated by a heavy rain which in-
undated the pond.

TABLE III.-PERIODIC INCIDENCE OF THE DIFFERENT STAGES OF ANOPHELES
IN LAKE ALICE IN DECEMBER, 1938 AND JANUARY, 1939.
(20 dips made in each check)

Date Checked Dec. Jan. Total
19 26 2 9 16 23 Number
Stage Number Collected Collected
First Instar ..... .. 94 11 10 8 16 12 151
Second Instar -...... 28 42 22 6 17 13 128
Third Instar .......I 32 19 47 11 7 13 129
Fourth Instar .......... 26 21 16 23 24 12 122
Pupa ..................... 0 1 2 2 3 3 11

Data presented in Tables III, IV and V represent a part of
the data taken in the studies made in Lake Alice. Table III in-
cludes data taken at weekly intervals from December 19, 1938
to January 23, 1939. The range of the water temperature is in-
dicated by records taken in January which was 18 on the 16th
and 17 C. on the 23rd. A peak in population occurred in each
successive stage at weekly intervals, indicating four or five
weeks as the time required for larval development. The actual
totals in this data indicate 'a larval decrease of only 19%, but be-
cause of the low temperature range and time involved there is








THE FLORIDA ENTOMOLOGIST


no tangible basis on which this data can be interpreted. An un-
usual number of pupae and pupal skins noted in the latter part
of this series indicates, however, that many representatives were
completing development, and the extended time of exposure to
predators is sufficient evidence to establish the indication that
predator efficiency was comparatively low during this period.
Table IV represents data taken in mid-April when the min-
now population had shown a considerable increase. The re-
corded temperature of the water indicates that it ranged between
28 and 290 C. A peak in population of each successive larval
stage was obtained by checking every other day; the peak in
population for the pupal stage was obtained on the third day
after the peak obtained in the fourth instar which indicates that
the maximum fourth instar population probably occurred after
the 16th, but the data taken on the 17th showed only fifteen
fourth instar larvae and no pupae. The number of forms in the
second instar on the 10th indicates that the peak in the first in-
star was taken on the decline; although no data were taken to
substantiate this indication, it may be assumed on the basis of
other series of data. These data indicate a 40% larval reduc-
tion with the greatest reduction apparently involving the third
and fourth instars which may be considered erroneous if it is
assumed that the peak obtained in the first instar was on the de-
cline. If this assumption is correct, the actual reduction during
this period should be greater than is actually shown. The pupal
incidence indicates that a considerable number were able to com-
plete development which in such a large breeding area would
result in a relatively high incidence of adults.

TABLE IV.-PERIODIC INCIDENCE OF THE DIFFERENT STAGES OF ANOPHELES
IN LAKE ALICE IN APRIL, 1939.
(20 dips made in each check)

iI I
Total
Date Checked 10 12 14 16 19 Number
Stage Number Collected Collected
First Instar .............................. 35 18 5 7 5 70
Second Instar ......................... 21 31 20 7 6 85
Third Instar ............-......---- .. 7 18 23 13 9 70
Fourth Instar ........................-- 6 5 9 16 6 42
Pupa .........................................- 0 1 3 1 5 10
_ _ _ _ _ ~ ~I ._ _









VOL. XXVI-No. 2


Table V presents data taken during May when the minnow
population had apparently reached its height in activity and
population. The records of the temperature of the water ranged
from 24 to 34 C. The peaks in larval populations can be followed
through fairly well in the first part of the month which indicates
that about seven days are required for larval development. All
the population data taken during May are given to show its con-
sistence since totals in the table give essentially the same per-
centage larval reduction as the totals of the data including only
that within the developmental cycle. These data indicate a lar-
val reduction of about 87% with the greater part of the reduc-
tion shown in the third and fourth instar populations. The con-
sistently low figures in the fourth instar and the scarcity of
pupae indicate that the number of forms completing development
is insignificant during this period.

TABLE V.-PERIODIC INCIDENCE OF THE DIFFERENT STAGES OF ANOPHELES
IN LAKE ALICE IN MAY, 1939.
(20 dips made in each check)
1 Total
Date Checked 1 3 5 7 9 11 139 171924 26128 Number
Stage Number Collected Collected
First Instar --... ----... .-. 49 31 28 17 7 10 17 12.12 18 11 11 223
Second Instar -..-...--.. ---.. 12 29 13 20 10 11 7 15 13 15 22 14 181
Third Instar .................... 6 4 10 12 11 8 5 7 6 3 4 9 85
Fourth Instar ....................... ..0 1 0 2 8 4 3 3 3 2 0 3 0 29
Pupa ....-...-... .............-. 0 0 0 0 0 1 0 1 1 0 0 3


Anopheles breeding continued in Lake Alice from mid-June
through August at such a low ebb that many tries were neces-
sary to obtain a minimum of ten successful dips, and of the forms
collected, very few had developed beyond the third instar. The
temperature of the water during this period ranged up to 380 C.
Temperature was apparently the predominant factor keeping
anopheles incidence low in this water during this period.
These data and observations indicate that the degree of
predator efficiency on anopheles breeding in permanent water
basins varies with the season and predator abundance. The
mosquito fish was the principal predator in an association which
included many other common predators; water scavenger beetle








THE FLORIDA ENTOMOLOGIST


larvae became the principal predator in an association in which
no minnows occurred.
This study indicates that the mosquito fish is a dominating
species. It is apparent that its efficiency as a predator of ano-
pheles increases with the increase in size of mosquito larvae, but
its efficiency in associations where protective vegetation and
debris occur is dependent to a marked degree on the activity of
other aquatic life both beneath and on the surface of the water.
This becomes evident because an undisturbed form, floating at
the surface of water against an object, is not likely to be de-
tected by minnows unless exposed by its own movements. Un-
like the mosquito fish, the efficiency of the water scavenger beetle
larva is dependent upon the habit of anopheles remaining im-
mobile at the surface of water in contact with vegetation or
some other floating object and its efficiency is apparently not
affected by the size of its prey; thus accounting for the inde-
pendent efficiency of this form as a predator of anopheles.









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Uhe
FLORIDA ENTOMOLOGIST
Official Organ of the Florida Entomological Society
Gainesville, Florida

VOL. XXVI JULY, 1943 No. 2

J. R. WATSON, Gainesville.--.------.. ..-... ----------.....Editor
E. W. BERGER, Gainesville....--.-------...... ..........-Associate Editor
C. B. WISECUP, Box 309, Plant City -....--...-..-....- Business Manager
Issued once every three months. Free to all members of the
Society.
Subscription price to non-members is $1.00 per year in ad-
vance; 35 cents per copy.


THE GREEN SCALE IN SOUTH FLORIDA
JOHN M. FREDRICK
(Continued from Vol. XXVI, No. 1, p. 15)
Five different species of ants have been observed attending
green scales for honeydew. Many different species of winged
Diptera and Hymenoptera, which apparently are in search of
honeydew, also may be noted on foliage infested with green
scales.
NATURAL CONTROL
Control by Insects:
Control of the green scale by insect predators and parasites
during the summer and fall months was observed to be practically
nil and was considered of little importance.
The twice-stabbed ladybeetle, Chilocorus bivulnerus Muls.,
was seen eating four green scale adults and two other species of
ladybeetles were sometimes observed on foliage infested with the
scales. Several species of internal dipterous and/or hymenop-
terous parasites and a predaceous thrips were infrequently en-
countered during the examination of the green scales. At least
two species of mites were often observed mingling with the green
scale crawlers and eggs underneath the adult scales, but they did
not appear to be harmful to them. Less than 3 percent of all
green scales examined were killed by their insect enemies in the
summer and fall months.









THE FLORIDA ENTOMOLOGIST


Control by Fungi:
Several different entomogenous fungi were found associated
with the green scales, and some of them apparently played an
important role in the natural limitation of the scales on citrus
during certain seasons of the year. In their descending order of
importance they were:
1. The white-fringed fungus-Cephalosporium lecanii Zimm.
2. A grayish blue entomogenous fungus.
3. Cuban aschersonia-Aschersonia cubensis.
4. Pink scale fungus-Nectria diploma B. & C. sp., perfect stage.
Pseudomicrocera henningsii (Koorders) Petch, imperfect stage.
5. A secondary fungus, Fusarium sp., which might be confused with
C. lecanii.
Of the various fungi under observation, Cephalosporium
lecanii Zimm. was the most common and apparently caused the
highest percentage of mortality. The next most common fungus,
the grayish blue one, also appeared to be very efficient, but it
was not nearly so widespread as the C. lecanii. Cuban ascher-
sonia was observed in only one grove and there it was only of
fractional value in destroying green scales.
The pink scale fungus was of no consequence on green scales.
Approximately a dozen specimens of it were found in the thou-
sands of scales examined.
This description of Cephalosporium lecanii Zimm. is quoted
from a paper3 given by John Parkin in the Annals of the Royal
Botanic Gardens: "The fungus shows itself to the naked eye
as a white or pale yellow powdery bloom around and to some
extent over the scales. The powdery or mealy appearance is due
to inuumerable conidial heads covering the hyphae."
During the early summer months C. lecanii was not very
plentiful but as the season progressed there was a marked in-
crease in the fungus-infected scales on citrus trees. On June 29
only 2.8 percent of all the scales examined in an unsprayed plot
in one grove were dead, and no C. lecanii was noted. On August
18, 50 days later, 61.2 percent of all the scales examined on the
same plot were dead and 68.3 percent of the dead showed the
mycelia of C. lecanii. The same trend of increased mortality co-
incident with an increased abundance of C. lecanii was observed
in an unsprayed check plot in another grove.

Fungi parasitic upon Scale-Insects (Coccidae and Aleurodidae): a
general account with special reference to Ceylon Forms." Annals of the
Royal Botanic Gardens, Peradeniya. Vol. III, Part I, March, 1906.









VOL. XXVI-No. 2


Through October this fungus was more generally distributed
over the trees and the total mortality had increased to 73 percent
of the scales examined which indicated that C. lecanii was a fac-
tor in keeping the infestation in check. Fifty-five percent of all
the scales examined at that time showed mycelia of the fungus.
C. lecanii was seldom found associated with green scales on
groundsels. It is possible that the open-type growth of these
plants does not permit humid conditions sufficiently favorable
for the development of the fungus. The fact that C. lecanii did
not affect green scales on groundsels to any extent may be the
reason for the continued heavy infestations on those plants.
Due to the apparent efficiency of C. lecanii in limiting green
scales on citrus, several attempts were made to artificially spread
this fungus on green scales not infected with it on both citrus
and groundsels. All attempts to inoculate apparently healthy
scales were unsuccessful.
Although C. lecanii is a factor in checking green scale infes-
tations, there are several reasons why artificial control may be
desirable rather than depending wholly on the fungus to keep in-
festations in check. If the weather is not suitable for fungus
development, the trees may not only become heavily infested with
green scales but the leaves will also be coated with sooty mold
which provides an excellent breeding place for purple and long
scales. Dead green scales that have been killed by C. lecanii
stick firmly to the leaves. This also affords shelter for purple
and long scale crawlers. In short, there might be a satisfactory
control of the scales by the fungus, but later an increase of purple
and long scales might occur which would cause considerable dam-
age. Consequently several experiments with oil sprays were
carried out to determine the effectiveness of oil on the scales and
how they might best be controlled.

ARTIFICIAL CONTROL
Control with Oil Sprays:
The green scale was found to be no more difficult to kill than
the average scale of the same type. As in all other species of scale
insects the crawler and intermediates were found to be the most
susceptible to an oil spray and the adults were the most resistant.
Citrus and Groundsels were the host plants used in the experi-
mental work.
Concentrations of from 1.0 to 1.7 percent actual oil were
tested for their effectiveness on green scales. One application of









THE FLORIDA ENTOMOLOGIST


1.5 percent oil resulted in satisfactory control, killing on an aver-
age 91.2 percent of the scales. The control obtained in plots that
received 1.6 and 1.7 percent oil was somewhat better, but there
was insufficient difference between the results obtained with the
1.5 percent oil and the two higher concentrations to warrant
using either of the latter. Concentrations lower than 1.5 percent,
namely, 1.0, 1.12, and 1.33 percent oil, killed a high percentage of
the intermediates and crawlers but did not kill a sufficiently high
percentage of the adults to consider these lower concentrations as
efficient one-application sprays on citrus.
Other experiments were conducted to determine the effective-
ness of one application and two applications, respectively, of low
concentration oil sprays so that they might be used on tender
ornamentals. Six plots sprayed with 1.0 percent oil gave on an
average 85.4 percent mortality. A second application of 1.0 per
cent oil made on the respective plots from 6 to 42 days after the
first spray resulted in a reduction of living scales to 3.3 percent
which is considered satisfactory control. In one plot, prior to
an oil spray, the stages of the scales were found to be in the fol-
lowing proportionate percentages: 10 percent adults, 30 percent
crawlers, and 60 percent intermediates. Three days after the
spray was applied counts showed that of the small percentage
of scales remaining, 29 percent were adults, 65 percent were
crawlers, and 6 percent were intermediates. The proportionate
percentage of increase of crawlers was due to the fact that, in
weaker oil concentrations, the adults that were not killed con-
tinued to deposit eggs. This accounts for the high percentage
of crawlers in the postspray count.
In one series of plots where a satisfactory control did not re-
sult from the 1.5 percent oil, a second application of 1.0 percent
oil reduced the population to the minimum. In one of these plots
only 70 percent control was obtained from a 1.5 percent oil. A
second application of 1.0 percent oil made 10 days after the first
spray killed all but 2 percent.
Results of a count made from leaves picked at random from
6 plots after the second application of a 1.0 percent oil showed
a population of .1 living scale per leaf which demonstrated that
the population was reduced to a minimum. Since all of the sec-
ond applications were made within a period of 6 weeks after the
first spray, none of the progeny of the females which survived
the first spray had time to mature. Probably the most satisfac-
tory results from two applications may be obtained if the second










VOL. XXVI-No. 2


spray is applied from 4 to 5 weeks after the first spray. All
females surviving the first spray will be given time to complete
oviposition so that all the young hatched may be killed by the
second application of oil.
The citrus trees in all plots were in good healthy condition
and there was no noticeable injury on citrus from any of the
concentration sprays even where the percentage of oil was as
high as 1.7. No burn resulted from any of the oil timing sprays
even when the 1.5 percent oil was followed in 7 days with 1.0
percent oil. Although no injury resulted from the oil timing
sprays, the second application should be applied only in case of
emergency.
Prevention:
Indications are that green scales may leave groundsels to
infest adjacent citrus trees if these plants occur around or near
a grove. On the west end of one grove where groundsels were the
most abundant and where the heaviest infestations of scales oc-
curred on them, citrus trees were correspondingly infested. As
the number of heavily infested groundsels decreased, there was
also a decrease in the number of infested citrus trees, and where
there were fewer groundsels with no infestations, the citrus trees
were apparently also free of scale.
With this in mind the possibility of a grove becoming infested
may be reduced by destroying all groundsels around or near
citrus groves, especially those bordering young citrus plantings.

ACKNOWLEDGMENTS
The writer is indebted an deeply grateful to Mr. W. L. Thompson of
the Citrus Experiment Station, Lake Alfred, for his having planned and
supervised the experimental control work and for his advice in the writing
of this report. Acknowledgment and thanks are due Mr. G. B. Merrill of
the Fla. State Plant Board for his assistance in the preliminary work and
for the identifications and measurements of the scales. Appreciation is ex-
pressed to Mr. Frank Stirling of Davie for his having kindly furnished a
laboratory building for the work at Davie.
Sincere thanks are due Dr. A. F. Camp in charge of the Citrus Experi-
ment Station for having improvised the spray outfit that was used, Mr.
Erdman West of the Florida Agricultural Experiment Station for his having
identified hosts plants and fungi, Mr. M. R. Smith of the Bureau of Ento-
mology and Plant Quarantine for the identification of two species of ants,
Dr. R. K. Voorhees of the Citrus Experiment Station for criticisms and
suggestions in the manuscript regarding the entomogenous fungi, and to
the many others who, although not mentioned here, cooperated fully in
facilitating the work.








THE FLORIDA ENTOMOLOGIST


DRAGONFLIES COLLECTED IN THE VICINITY OF
FLORAL, ALABAMA1
By MIKE WRIGHT
The dragon flies discussed herein were collected by the writer
in the vicinity of Florala, Ala., from April 29 through May 26,
1942. The publishing of these notes, even though they are frag-
mentary, was deemed advisable because of the absolute lack of
dragonfly record from this locale.
Florala is in Covington County, Ala., and its southern limits
are but a short distance from the Florida-Alabama State line.
The collecting was done within a 10-mile radius of Florala and
the localities visited are briefly described below.
1. Lake Jackson.-A small lake at the south end of Florala,
lying half in Alabama and half in Florida. Its shores are marshy
and in places heavily wooded. In some places the marshy areas
are replaced by standing water, which affords excellent breeding
habitats for Lestes, Plathemis, and other marsh-loving forms.
2. Svea.-A small settlement about 8 miles southwest of
Florala, in Okaloosa County, Fla. There were several small
creeks and "bay heads" in the area in which dragon flies were
found.
3. Lockhart.-A small sawmill settlement in Covington
County, Ala., about 2 miles northwest of Florala. Streams,
"bay heads," and the sawmill pond and stream afforded habi-
tats for odonate breeding.
4. Pond Creek.-A typical creek of this area, which me-
andered through the countryside and, owing to erosion, had pro-
duced a noticeable valley. The borders of the stream were in
general heavily wooded and gave way, in many places, to swampy
or marshy areas. Pond Creek was about 4 miles south and west
of Florala.
5. Flemming Creek.-Similar to Pond Creek and located
about 6 miles southwest of Florala.
6. Natural Bridge Creek.-Located in Walton County, Fla.,
about 8 miles east of Florala. A very interesting stream that,
in the area studied, disappeared several times beneath the
ground, leaving a series of pools. It had a series of riffles and
SUnited States Department of Agriculture, Agricultural Research Ad-
ministration, Bureau of Entomology and Plant Quarantine.
The writer wishes to express his sincere appreciation to Dr. Lyman
S. Henderson, at that time connected with the white-fringed beetle labora-
tory at Florala, for his kindness in personally taking the writer to all of
the above-mentioned collection areas. Without the direction of Dr. Hen-
derson many of the species listed herein would not have been found.









VOL. XXVI-No. 2


wide sandy shores which, in places, were covered by shrubs 8 to
10 feet high. Behind these was a heavily wooded area which
gave way to grasslands.
7. Pond A.-In Walton County, Fla., about 6 miles east of
Florala, an open woodland pond exhibiting considerable fluctua-
tion of water level. A thin fringe of trees around the edge gave
way to open grassy fields. Few or no emergent or true aquatic
plants were present.
8. Pond B,-About 2 miles south of Florala, in Walton
County, Fla., was a beautiful pond completely hidden in the
middle of a densely wooded area. The trees came almost to
the edge of the water, leaving a narrow sandy beach. The pond
was filled with emergent and submerged plants. Many dragon-
flies, including our first specimens of Teleallagma daeckii, were
seen or collected at this pond. A study of the odonate fauna of
the pond during the entire summer would undoubtedly show sev-
eral times the number of species taken during our study.1

NOTES ON THE SPECIES OF ORDONATA FOUND
1. Agrion dimidiatum (Burmeister). Pond Creek, May 3, 1942; Nat-
ural Bridge Creek, May 16, 1942; Pond Creek, May 23, 1942. This is a
beautiful insect and inhabits the same general habitat type as A. macula-
turn Beauvois. Both species prefer a freely flowing and usually heavily
shaded brook or stream. At Pond Creek hundreds of individuals were ob-
served under the highway bridge crossing the creek. When disturbed they
flew out into the open, but soon returned to the shaded portion of the creek.
In all our collecting of this species, as well as A. maculatum, we have never
taken individuals at any great distance from the water. They are not
swift flyers but do considerable moving, usually up and down the stream,
and perch at frequent intervals on the waterside vegetation. At the time
of collecting at Pond Creek (in May) there were probably from 6 to 8
times as many males as females; in fact, we had to hunt for a long time
before a female was flushed.
In the several years that I have been collecting Odonata in the Gulf
coast area of Louisiana, Mississippi, and Alabama I have taken this species
but once before, in Baldwin County, Ala. Throughout the central Gulf
coastal area Agrion maculatum is encountered in practically all shaded,
flowing streams. We have never found both species inhabiting the same
creek. At Pond Creek and Natural Bridge Creek, in the Florala area, A.
dimidiatum was found in considerable numbers but A. maculatum. was not
taken by us in the entire Florala area. Likewise at Rocky Creek, in Bald-
win County, Ala., A. dimidiatum was very abundant, while A. maculattum
was entirely absent. The converse holds for those streams along which we
have taken A. maculatum. In Baldwin County, Ala., we took A. maculatum
along a creek a few miles distant from Rocky Creek, but were able to find
only one species at each creek. We are unable to explain this peculiarity,
because the creeks inhabited by both species appeared identical to us. Eco-
logical analyses of such streams might show chemical or physical differences
not apparent to the collector. Whatever these effects, each species becomes
the dominant dragonfly in the stream inhabited by it. (To be continued)




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