SPECIES ABUNDANCE RELATIONSHIPS OF AQUATIC INSECTS

IN MONOTYPIC WATERHYACINTH COMMUNITIES IN FLORIDA,

WITH SPECIAL EMPHASIS ON FACTORS AFFECTING DIVERSITY

By
JOSEi'H KESTUTIS BALCIUNAS

A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF

THE UNIVERSITY OF FLORIDA

IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE

DEGREE OF DOCTOR OF PHILOSOPHY

UNIVERSITY OF FLORIDA
1977 '

Dedicated t;o my father. Jurgis ,
whose support made this possible.

ACKNOWLEDGMENTS

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. Minter J. VJestfall,
and Dr. Frank Young. My special thanks to Mr. William
Beck for identifying all tliousand-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 Mr. Walter
Offen of the University of Florida Department of Statistics
for t:heir help with statistical analyses of my data. I would
also like to thank my former roommate, Mr. Roger Jones, pres-
ently at tlie Dartmoutli Department of Phvsics, for his guid-
ance concerning the mathematical portions of this study.
I also acknowledge Florida Collection of Arthropods
and the Northeast Regional Data Center (NI'IRDC) for use of
their facilities and Florida Department of Natural Resources
for their partial support of this study.

T also wish to acknowledge a special debt of gratitude
to Linda 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.

TABLE OF CONTENTS

Page

ACKNOI'JLEDGMENTS iii

LIST OF TABLES vii

LIST OF FIGURES viii

ABSTRACT ix

INTRODUCTION I

LITERATURE REVIEW 3

Eichhornia crassipes (Martius) Solms-Laubach .... 3

Description 3

Taxonomy 3

Distribution--Florida 5

Productivity and Reproduction 7

Environmental Requirements 8

Water Quality 10

Economic Importance 12

Habitat for Aquatic Insects 15

METHODS 19

Samj-ile Site Selection 19

Collection Methods 21

Water Quality 21

Identification 24

Analyses 28

RESULTS AND DISCUSSION 41

General 41

Comments on Species List 41

Physical and Chemical Variable

Interrelationships 119

Regression Analyses 120

TABLE OF CONTENTS (Continued)

Page

RESULTS AND DISCUSSION (Continued)

Comparison of Study Sites 120

Description 120

Species List Comparisons 123

Estimation of Total Number of Species 128

Factors Affecting the Number 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

SUMIIARY 150

REFERENCES CITED 152

APPENDIX A 164

Fortran program for Shannon's and Simpson's
diversity indices (and Brillouin's, when possible)

APPENDIX B 165

Fortran program for rarefaction diversity index

BIOGRAPHICAL SKETCH 166

LIST OF TABLES

Page

Table 1. List of collection sites 20

Table 2. Annotated list of insects 42

E]phemeroptera 42

Odonata 45

Hemiptera 55

Trichoptera 67

riegaloptera 68

Coleoptera 69

Lepidoptera 101

Diptera 102

Table 3. Ten most abundant insects 117

Table 4. Ten most frequent insects 117

Table 5. \'Jater quality correlation 121

Table 6. Ten most abundant insects, Camps Canal 124

Table 7. Ten most frequent insects, Camps Canal 124

Table 8. Ten most abundant insects, Lake Alice 125

Table 9. Ten most frequent insects, Lake Alice 125

Table 10. Ten most abundant insects, 1-75 ditch 127

Table 11. Ten most frequent insects, 1-75 ditch 127

Table 12. Mean values for diversity indices 143

Table 13. Order of entry of variables into diversity

models 148

LIST OF FIGURES

Figure 1. Generalized species accuinulation curve .

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

Figure 3. Species accumulation curve, Camps Canal

Figure 4. Species accumulation curve, Lake Alice .

Figure 5. Species accumulation curve, 1-75 ditch .

Figure 6. Species abundance curve, Camps Canal . .

Figure 7. Species abundance curve. Lake Alice . .

Figure 8. Species abundance curve, 1-75 ditch . .

Page
34
34
130
131
132
136
136
137

VI 11

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

SPECIES ABUNDANCE RELATIONSHIPS OF AQUATIC INSECTS

IN MONOTYPIC WATERHYACINTH COMMUNITIES IN FLORIDA,

WITH SPECIAL EMPHASIS ON FACTORS AFFECTING DIVERSITY

By

Joseph Kestutis Balciunas

December 1977

Chairman: Dale H. Habeck

Major Department: Entomology and Nematology

Collections of aquatic insects beneath monotypic 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-
identif ications by previous worlcers and a much greater range
of aquatic entomofauna. Although the loi'j 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 v/hich showed that the 3 repetitively sampled sites
were significantly different liased 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
collected .

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 v/ere calculated for all my
collections. All 3 indices indicated an increase in diver-
sity with decreasing values of alkalinitv 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 betv/een the 3 study sites, indicating a
loss of information due to the reduction to a single statis-
tic. The use of diversity indices would thus appear to have
more limitations than might be Inferred from their popular-
ity in ecological literature.

INTRODUCTION

Although v;aterhyacinths 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 waterhyacinth mats is relatively devoid of life
due to a reduction of dissolved oxygen. Of the two previous
studies of aquatic insects beneath waterhyacinths , one xvas
restricted to canals in South Florida, tlie 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 13 Florida counties, I hoped to provide a better
picture of the variety and extent of the aquatic life in
this common Florida habitat.

Many 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
measuremients of the waterhyacinths and a number of water
quality parameters, I hoped to elucidate the environmental
factors affecting species composition and abundance. Repeti-
tive sampling of 3 study sites also would allow detection of
seasonal changes in the composition 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 differeiit 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 lognormal 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 onlv illustrated their
utility for ecological research but also helped define the
important parameters and their interactions in these water-
hyacinth communities and the methods which could be used to
detect them.

LITERATURE REVIEVJ

Eichhornia crassipes (Martius) Solms-Laubach

Description

The waterhyacinth , Eiclihornia 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 cm long with a small
apical orbicular-renif orm lamina with a
lacerate [serrate?] margin; submerged leaves
never evident. Inflorescence variable,
internodes betv/een the spathes nearly ab-
sent; inferior spathe with lamina 1-5 cm
long, the sheath 3.5-7 cm long. Flower 4-6
cm long; perianth light purple or rarely
white, tube 1.5-2.0 cm 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
mm with 10 longitudinal ridges.

Taxonomy

Eichhornia is one of 9 genera, all aquatic, of the
pickerelweed family, Pontederiaceae , all but 2 of which are
considered endemic to the Nev; World (Cook et al. 1974). The

waterhyacinth is the most widespread of the 7 species of
tliis 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).

Waterhyacinth 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 (Mart.) Solms in DC, Monogr.
Phan. 4:5 IT~T^"81 .

Pontederia crassipes Mart., Nov. Gen. 1:9.

r~^. 1824.
Piaropus crassipes (Mart.) Raf., Fl. Tell. 2:

~81 1837.

Eichhornia speciosa Kunth, Enum. PI. 4: 131.

Eichhornia cordif olia Gandog. , Bull. Soc.
Bot. France 66 779^ 1920.

The scientific synonyms E. speciosa and Piaropus cras-
sipes are especially common in the literature even 50 years
after Solras-Laubach ' s revision.

While the binomial Eichhornia crassipes has gained wide-
spread acceptance in the last 30 or 40 years, the authorship
of the name is often coiifused, sometimes being mistakenly
attributed to Kunth. The correct form for the scientific
name with the authors abbreviated is "Eichhornia crassipes
(Mart.) Solms".

E. crassipes has a variety of common names in different
parts of the v.^orld, with Bock (1966) listing 48 names from

18 countries. In tlie English language the name waterhyacinth
is commonly used. The structure of the name varies, however,
sometimes being v;ritten 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) .

Distribution- -Florida

Waterhyacinth, now generally believed to be a native of
South America, is widely distributed tliroughout 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. Coin (1943) cites a University of Florida
botany professor with crediting the U. S. introduction of
waterhyacinth 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 (Govcanloch 1944) that waterhyacinth
was introduced to South America 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. Most authorities agree that,
directly or indirectly, the waterhyacinths 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 Woods 1962).

Although the precise time and area v;here waterhyacinths
were introduced into Florida is not surely kno^vn , the earli-
est reports place it in the St. Johns River near Palatka in
1890. A New York newspaper account (Anonvmous 1896) quotes
a ^Tr. J. E. Lucas of Palatka that the waterhyacinths were
introduced by a Mr. Fuller [in 18911 into the St. Johns
River seven miles north of Palatka at Edgewater Grove from
plants brought originally from Europe. V/ebber (1897) places
the point of introduction ". . . about 1890, at Edgewater,
about four miles north of Palatka" (p. 11), vjhile Tilghman
(1962), an old resident of Palatka, states "Florida's first
water hyacinth was placed in the St. Jolins River by a winter
visitor, Mrs. W. F. Fuller, at San Mateo, five miles south of
Palatka" (p. 8). Most subsequent workers (Buckman 1930, Penfound

and Earle 19''t8, TabiLa and Woods L962, Seabrook 1962, Zeiger
1962, Raynes 1964, and many others) give similar versions of
the introduction based directly or indirectly on the above
accounts .

In 1897 waterhyacinth distribution in Florida was thought
to be confined to the St. Johns River and its tributaries and
a fev; landlocked lakes (Webber 189 7) . In 1930 waterhyacinths
seemed still to be confined to the 42-square-mile (26,800
acres) St. Johns River drainage (Buckraan 1930). By 1947 the
estimated area of infestation increased to 63,000 acres and
to approximately 80,000 acres by 1962 (Tabita and VJoods 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).

Pro ductivity and Reproduct ion

This increase in the area infested, despite massive con-
trol measures dating back over 75 3'ears , points out the re-
markable reproductive ability of this plant. Considered
one of the world's most productive photosynthetic organisms
(VJestlake 1963), waterhyacinths 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 and standing crop compiled from many different
sources .

Such rapid increase in new plants is due primarily to
vegetative reproduction (Hitchcock e_t a_l. 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
(Bock 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
waterhyacinths 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
like waterhyacinth can easily become established and out-
compete the native flora in such disturbed aquatic systems.

Light . Waterhyacinths require reasonably high light
intensities for growth, at least 607o full sunlight according
to Bock (1966). Penfound and Earle (1948) found that the

lighL intensity in July above a waterhyacinth mat was 420
footcandles and noted that plants at 130 footcandles were
dying. Knipling e_t al. (1970) found that photosynthesis

increased from 7.8 mg CO /dm" leaf surface/hr to 16.1 mg/

2
dm /fir when light intensity increased from 1450 to 8000

footcandles .

Air temperature. Waterhyacinths 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 21°F
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 v.'aterhyacinth ; however, it is undoubtedly fairly
high, as most prolific growth usually occurs during summer
when daytime temperatures are frequently in the upper 80 ' s
and low 90 ' s °F. Balciunas (unpublished data) observed lux-
uriant growth in a greenhouse where daytime summer tempera-
ture was consistently about 100°F.

\/ater temperature. Knipling e_t ad. (1970) determined
that the optimimi water temperature for waterhyacinth was
28-30^C (82.4-86.0"F) but that growth was relatively high
over the range of 22-35°C ( 71 . 6-95 . 0 '^P') • Waterhyacinths
will survive a water temperature of 34°C (93.2°F) for 4 or
5 weeks (Penfound and Earle 1948), but higher temperatures
are detrimental, with negative growth occurring at 40°C (104°F)

iO

VJatcr (lepLh. Waterhyacinths can grow on land; Penfound
and Earle (1948) noted survival of plants for up to 18 days
out of v;ater. 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 waterhyacinth growth (Morris 1974) .

Water Quality

Hydrogen ion concentration. Waterhvacinth seems tolerant
to pll values normally encountered in aquatic systems. Haller
and Sutton (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 . Penfound and Earle (1948)
found that the pH of water beneath waterhyacinths usually
ranged from 6.2-6.8 but that waterhyacinths could tolerate
extremes of 4-5 and 9-10. Chadwick and Obeid (1966), in com-
paring growth of waterhyacinths and water lettuce (Pistia
stratiotes L.), found that optimal growth for waterhyacinths

ccurred 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 waterhyacinths, alligator weed (Alter-
nanthera philoxeroides (Mart.) Griseb.), or neither weed,
found there was little difference in the pH preferences of
the plants and that the pH of areas with waterhyacinth was
slightly lower (7.06 ± 0.84), though not significantly, than
the pH of areas having no aquatic weeds (7.55 ± 1.06).

o

li

Nutrients . Dymond (1.9''48) and Hitchcock e_t al . (1949)
found that wa terhyacinths grow well in nutrient-poor as well
as in nutrient-rich water but that added nutrients favor
growth. Haller e_t al^. (1970) found that less than 0.01 ppm
phosphorus was limiting to waterhyacinth growth and that above
this level phosphorus was absorbed in luxury amounts. Haller
and Sutton (1973) found that maximum growth occurred in water
with a phosphorus concentration of 20 ppm and that levels
greater than 40 ppm were toxic. Boyd and Scarsbrook (1975)
added fertilizer at 4 different levels to waterhyacinth 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
100'/'. seawater (Bock 1966) , waterhyacinth is intolerant to salt
water, with Buckman (1930) listing a survival time of only
24 hrs . Penfound and Earle (1948) found that waterhyacinths
did not tolerate more than slightly brackish water and were

12

not found in lakes or streams with an average salinity greater
than 157, seawater.

Alkalinity. Center and Balciunas (19 75) 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 waterhyacinth
growth.

Center and Balciunas (1975) found waterhyacinths more
tolerant of low iron levels than alligatorweed. Morris (1974)
found no correlation between waterhyacinth growth and the
levels of copper and iron at his study sites.

Economic Importance

Problems . The explosive growth of waterhyacinth has
caused it to be ranked as one of the 10 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 main 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 manv aquatic organisms;

13

(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
spavming 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) Monetary and ecological costs of control;

(14) Rendering unsightly and aesthetically unpleasant
the water surfaces which they completely cover.

Control . The U. S. Armiy 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 for waterhyacinth control (Center
1976). Morris (197^) cites a USDA source for a $12-$16 mil-
lion estimate of the costs of waterhyacinth control in Flor-
ida in 1973.

14

The literature on waterhyacinth control is enormous.
There is even a Hyacinth Control Journal (renamed in 1975
the Aquatic 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
Charudattan (1975). Mitchell (1974) reviewed habitat manage-
ment as a means of aquatic weed control.

Utili;:ation . 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-
hyacinths, the main ones of which are:

(1) Removal of nutrients from v/ater, including use of
waterhyacinths in sewage treatment;

(2) Protection of shorelines from erosion;

(3) Use as mulch and fertilizer;

15

(4) Use as a source oi produclion oF natural gas;

(5) Increase in aquatic organisms utilizable as fish
food ;

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

(7) Shading out of nuisance submerged plants like
Hydrilla;

(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 x-/rappers , ice chests, paper;

(10) Aesthetic appeal of beautiful blossoms and luxuri-
ant green foliage.

Habitat for Aquatic Insects

The insects found beneath waterhyacinths have received
little attention. Most of the literature about insects assoc-
iated with waterhyacinths deals V7ith those v/hich might have
potential as control agents through their feeding activity
or transmission of pathogens. Fred Bennett of the Common-
v/ealth 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 provided 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

16

spp., which build their pupal case in the root hairs of water-
hyacinths (DeLoach 1975) .

Waterhyacinths ' 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'llara (1968) believes that waterhyacinth has a greater inter-
face area than any other aquatic plant.

Although Coin (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 (Wakefield and Beck 1962, Haller and Sut-
ton 1973, liorris 1974). The blue color frequently seen in the
roots, often cited as a diagnostic aid, is also due to water
quality. Plants gro\-m 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) .

V/hile 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

17

water undei- the center of the mat being "... unsuitable for
the existence of most forms of plankton and aquatic insect
life." (Lynch ej; 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 xvaterhyacinth-inf ested ponds is due to
shading out of phy toplankton by waterhyacinths .

Few workers have actually surveyed the aquatic entomo-
fauna of waterhyacinths. Coin (1943) surveyed the lower ver-
tebrate forms of waterhyacinth communities but he mentions
only one insect, the midge Chironomus . 0 ' Kara (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 waterhyacinths,
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 mentions some in-
sects, identified only to family or order, which serve as
food for fishes living in waterhyacinth-covered ponds.

18

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 sfiecies 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 Anopheles 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 waterhyacinths increase mosquito production. However,
Viosca (1924; cited by Barber and Hayne 1925) , Mulrennan
(1962) and Ferguson (1968) believe that v/aterhyacinths 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 v/itb waterhyacinths are casual references by ento-
mologists to the habitat v/here a certain species was col-
lected, e.££. , Blatchley (1914, 1925), Young (1954).

METHODS

Aquatic insects were collected 88 times in 37 different
waterhyacinth 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) x^7ere 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-weGk intervals during
all of 197A. 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 waterhyacinth 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,
VJolfia spp. and Wolfiella spp., was sometimes present mixed
with the Lemna. These floating macrophytes were seldom

19

Table 1. List of collection sites.

20

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fli I ,

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II J'.M
1! J"l

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,

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r

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'

\ N ■ I

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r

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lr.41.

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SWAL-

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r'--

[1

<;Tt.i: r

'•-

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M_VF t 1

" •> ^■'' •^ 'i >■:■ J '■-;■ , A I / , ,.i -, .-

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UNI V. :^ =1 A. , r,- ■ N. .VI I L .

nV :-, .' ,?.(.■. MO ir> ,■ , Ji .-.'^^ ML. A -

W, CI 1 7." . s ■■! ' %: C ' 7I . r.'

MV ■-^' - 1-1 nr \■^ ,r . ,. . t-,,,,„ f

1 T JUN
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21

abundant except in a few places where waterhyaclnth growth
was poor and the waterhyaclnth 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 waterhyaclnth 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 v/as 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; otherv.'ise, 2 Styrofoam billets
allowed me to reach and sample the interior of the mat by
alternately standing on one billet and moving tlie 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 waterhyaclnth
mat was sampled for approximately 1 hour, usually divided
into 2 half-hour subsamples.

22

If the waterhyacinth 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 vi/ater. The
contents of the net and the waterhyacinths were washed in a
pail of water, then small portions of v/ater 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 well 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 he 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.

23

SLandardized area. A sampler which would cut through
a waterhyacinth mat and capture the organisms underneath was
designed and constructed. It consisted of a rectangular
aluminum box, SO 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 waterhya-

o

cinth mat, cut a 1 /5-square-meter (0.2 m ) 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 waterhyacinth 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 waterhyacinths 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 do^^m 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 beneatl) the waterhyacinth mat. As with
the standard- t ime sampling method, plant height, root length
and water depth as well as number of pilants and petioles in-
side the sampler v;ere recorded. Water temperature at a depth
of approximately 15 cm was also recorded.

24

Water Quality

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 ±n pint-sized Whirl-pak plastic
bags labelled with the collection number. Total alkalinity,
total hardness, pH and specific conductance of one sample
were tested immediately, using a portable Hach 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-
portant .

The methods applied to the water samples were:

alkalinity (total) -- titration ;

chloride-- titration , mercuric nitrate;

copper--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, Phos Ver III;

potassium-- flame emission spectrophotometer;

specific conductance--direc t measurement, conduc-
tivity probe;

sulphates- -turbidimetric , Sulfa Ver IV.

25

IdenLif ica tion

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, and the subsequent loss of some specimens and
poor quality of others caused the termination of this approach.
Subsequently ail 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. Lev/is Berner of the

26

University of Florida kindly checked the identifications of
some representative speciniens.

Dragonfly (Odonata : Anisoptera) nymphs were identified
using the keys of Wright and Peterson (19A4) and Needham and
Westfall (1955). Damselflies (Odonata : 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. Minter 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. VJestfall 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) v/ere identified using Chapman's
(1958) key; water-crawling Inigs (Naucoridae) were identified
using La Rivers' (1948, 1970) keys and by construction of
life series of nymphal stages. Dr. Jon Herring, USDA Syste-
matic Entomology 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.

Caddis fly (Trichoptera) larvae were determined using
Wallace's (1968) key. Dr. Oliver Flint at the Smithsonian
checked all my caddisfly identifications. Species level
determination was frequently impossible.

27

Dobsonfly (Megaloptei-a : 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 Maryland. 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 knov/n and even the identi-
fication of adults \^7as very difficult. I was successful in
rearing some larvae to adult stage. Dr. Dale Habeck, Univer-
sity of Florida, and I were 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 vjere checked by Dr.
Spangler .

Dr. Dale Ilabeck also identified the aquatic Lepidoptera
larvae .

Mosquito larvae (Culicldae) 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

28

Diptera larvae could be ideatified to the generic level using

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

Diptera larvae and pupae could be placed only at the family
level .

Analyses

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
diversity .

The choice of diversity indices is enormous, with much
confusion about terms and applicability (Hurlbert 1971, Peet
1974) . Much of the confusion results from the dual concepts
which most, but by no means all, authorities believe an in-
dex 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.

29

The 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. Most 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). Hurlbert (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 (Williams 1964, Ivhittaker 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 - Z "^±(^11^
1=1 ~nXN-1)

where N is the total number of specimens in the collection,
n. is the number of specimens in the
the number of species in the sample.

n. is the number of specimens in the i — species, and s is

30

Mcintosh (1967) suggested another index:

Mcintosh'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, xs/hile Bullock (1971) criticizes
its applicability and sensitivity.

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

H

■ . Z_ p . log p . ,

where p. is the proportion of the total specimens comprised
by the i— 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 ai:Ly randomly sel-
ected individual. The greater the
number of species and the more nearly
equal their proportions, the greater
the uncertaintv and hence the diversity.
(1966a, p. 131)

Althougli the most popular diversity index, the Shannon-
Weaver index is also the most widely criticized. Monk (1967)
and Sager and Hasler (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 Foole (1974) believe Shamion ' s index most sensitive to

31

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 Feet (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!/ni In^ ! . . .n^) .

Unfortunately, this involves computing very large numbers.
Any integer factorial greater than 69 ! results in a number
larger than 10'"°, 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. Hov;ever , the substitution of the Sterling's approx-
imation for the factorial results in this index becoming
equivalent to the Shannon-Weaver index (Peet 1974) .

Hurlbert 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
wliich combine both species richness and species evenness,

32

i.e., heterogeneity indices. He believes that there are 2
useful indices, one of which is modification of the rarefac-
tion index E(S ) 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, Siraberloff
1972) , is necessary because larger samples would contain more
species than a smaller one even if they v/ere drawn from the
same community. Hurlbert (1971) and Simberloff (1972) pro-
vide similar, correctly "scaled", calculating formulae for
the rarefaction index;

E(S ) = E^ [1 -
n i=l

N - n,

/

Wliile this results in a scaled estimate of species richness,
and Peet (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-Weaver index, H', since it is the most commonly used
index in recent ecological literature; Simpson's index, D,
since it overcomes some of the shortcomings of H'; and the

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

n

rationality and ease of interpretation. I wrote a small
Fortran program, shown in Appendix A, which calculates

33

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(S^^), I modified slightly a program cited
in Simberloff (19 72) and Heck e^ al. (19 75) 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, v^7ith 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

34

.r^

/

Figure 1. Generalized species accumulation curve

(iwKiH'iK r>, Spp

Figure 2. Lognormal species abundance curve
(from Preston, 1948).

35

species accumulation curve. Unf ortunatelv , this asymptote is
frequently attained only when the total number of individuals
sampled is very large, sometimes 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(l - e ) ,

where a is the asymptote for the curve. Rewritten in terms
of the species notation previously used, this equation be-
comes :

c-'- /I "bn
s=S"(l-e ).

The estimated total number of species in the collecting area,
S'-'-', and the constant, b, can be determined from a curve fitted
to the 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 from inspection of the data, the
approximate value for b is not readily apparent. However, I

36

v;as 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 ,

then taking the derivative results in:

ds = bS-e dn

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

ds/dn = bS"e

Taking the natural logarithm of both sides results in the
expression :

ln(ds/dn) = ln(bS") + (-bn).

Thus the logarithm of the slope fits the general equation for
a straight line:

y = p. n + S 1 X ,

where the intercept Bg equals ln(bS'''), and the slope Bj equals
-b. The slope ds/dn of the original equation can be approxi-
mated by AS/An, the increase in the number of cumulative
species over the number of specimens added with each additional
collection. Thus, plotting ln(As/An) against the cumulative
number of specimens, n, approximates plotting ln(ds/dn) versus
n. Fitting a straiglit line to the resultant points by using
the least squares procedure provides the value Bj, which is a

3 7

good approximation of b. Plugging 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-'O 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, W. Preston first presented this method
in 1948 and elaborated on it in 1958 and 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 h and 8 individuals.
Any species which falls on an interval boundary is split
equally between both octaves, tlTUs a species containing 4
specimens is counted as contributing one-half to the second
octave (2-4 individuals) and one-half to the third octave

38

(4-8 individuals) . Thus t.lie 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
shovm 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 = s^e-^aR)

where s is the number of species in the modal octave, R
o o

(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 Department of Statistics at the Univer-
sity of Florida are awaiting arrival of some special statis-
tical tables to enable them to do this. Although most texts

39

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^'' = s /IT/ a
o

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. IVliile extremely rough, the S"
derived by this method can be compared to S" derived from the
species accumulation curves.

40

For othei- analyses of my data I used the 76.4 version
of a variety of statistical computer programs which collec-
tively are known as SAS (Barr e_t al. 1976) . The most commonly
used statistical procedures were standard descriptive sta-
tistics (PROC MEAN), correlation (PROC CORR) , linear regres-
sion (PROC GLM) , stepwise multiple regression (PROC STEPWISE),
nonlinear regression (PROC NLIN) , 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 IBM 370/165 computer (later replaced
by an AMDAHL 470 V/6) at the Northeast 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 diversitv studies.

RESULTS AND DISCUSSION

General

Comnients 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 forms 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)

41

42

Table 2. An annotated list of insects collected in
x^7aterhyacinth 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 X'/ould 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 (57o) of occurring by chance are men-
tioned. UTiile the probability p takes into account the
number of observations, it is overly sensitive at low values
of n. Correlations v/hich have less than 5 paired observa-
tions (n<j) therefore have not been included. Maximum den-
sity per square meter is given for species collected using
0.2 square meter sampler.

Ephemeroptera (Mayflies) --nymphs

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 m.ade up 41 . 97o of the
specimens collected there. Katz (1967) mentions collecting
the genera Brachycerus , Cloeon, and Hexagenia in addition to
Caenia from hyacinths in the VJithlacoochee River. The first
two genera are probably misidentif ications due to their dis-
tribution and ecological requirements. O'Hara (19ol) col-
lected Callibaetis f loridanus and Caenis diminuta from
waterhyacinth- covered canals in South Florida.

Baetidae

1. Callibaetis f loridanus Banks --45 specimens from
12 collections at 8 different locations in 6 counties.

4J

Collections: 2, 20, 21, 45, 48, 50, 75, 82, 87, 88,
98, 102.

riaximum density: .6/plant or SO/m"^ at #87.
Water quality preference: nitrates, r=-.859, p=.028,
n=6.

Nymphs of C. floridanus, knovm to inhabit brackish water,
"... have the widest limits of toleration of any mayfly
nymph in North America" (Berner 1950, p. 196). Although
this species was collected numerous times in waterhyacinth
roots by myself and by O'Hara (1961), Berner (1950) does not
believe them common inhabitants of waterhyacinths due to low
oxygen levels .

I collected the majority of nymphs of C . floridanus
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
pattern .

^- 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.

44

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.

2
Maximum density: .25/plant or 12.5/m at #87.

Berner (1950) believes C. pretiosus to have similar

ecological requirements as C. f loridanus except that it is

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

water .

Caenidae

3. Caenis diminuta Walker--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, 85, 87, 88, 89, 92, 93, 94, 97, 98. 100, 102, 103.

o

ilaximum density: .7/plant or 35/m'- at #87.

Insect associations: Hydrocanthus oblongus Sharp,
r=.841, p=.002, n=10.

riy most commonly collected mayfly, it is also recorded
by O'Hara (1961) and is probably the Caenis sp . collected
by ICatz (1967). According to Berner (1950), this species
prefers small ponds, especially with emergent vegetation,
but is usuall}' not found in water covered by waterhyacinths .

There is an extremely significant correlation with the
noterid beetle nydrocantlius oblongus which probablv indicates
that these species prefer the same set of environmental con-
ditions .

tJymphs were collected throughout the year.

45

Heptageniid a e

4. SL'enacron. interpunctatum (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; Ijv?- at #73.

Formerly known as S tenon ema proximum, S. interpunctatum
nymphs are usually inhabitants of large streams and sand-
bottomed lakes v;ith little vegetation. Dr. Berner (personal
communication) finds their existence in wa terhyacinth roots
to indicate a possible broadening of the species' ecological
requirements .

Most of my specimens were collected during the fall and
winter months .

Odonata (Dragonflies and Damsel tY ies) --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 frl02.
Odonate nymphs were the most coinmon arthropod group in
VJahlquist's (1969) study of fish food organisms in experi-
mental ponds in Auburn, Alabama.

Since all odonate nymphs are predaceous, their abundance
implies a large prey population. The most probable prey item,
at least in nuuilujrs , would lie Llie aiiiphipod Hyalella azteca
(Saussure) . fiansen e_t al^. (1971) reports 66 amphipods per
waterliyacinth plant, but in the field they were probably more

46

numerous, ivith a bucketful of water frequently containing
literally thousands of araphipods . O'Hara (1961) recorded
as many as 81,000 per square meter at one site.

Zygoptera (Daniself lies) Nymphs

This suborder, with 752 specimeiis , comprised 13.77o of
all specimens and 73.2% of all odonates . Damselfly nymphs
were found in most collections, with one species, Ischnura
posita, being found in 53.474 of my collections, making it
the most frequently represented species. VThile only 7
species and the E. signatum-pollutum com,plex 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 waterhyacinths in canals, while Katz (1967) records
4 genera of damselflies from waterliyacinth roots at the
Withlacoochee River.

Coenagrionidae

Of the 3 families of damselflies known from Florida,
this was the only one v/hich was found beneath waterhya-
cinths. Of the 35 species in this family that occur in
Florida (Johnson and Westfall 1970), 7 were collected in
waterliyacinth roots.

5. Argia apicalis (Say;--1 specimen collected at Lake
Talquin, Gadsden Co.

Collection : 96 .

4/

2
Density: .05/plant; 5/m .

Due to the rarity of this species in my collections,

no significant conclusions can be drawn concerning its

preferences or associations. VJhile usually considered a

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

in Indiana (Montgomery 1944) .

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

Collections: 48, 102, 103.

Maxim^um density: . 769/plant at #48; 35/m^ 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 19 74.

7. Enallagma pollutum (Hagen)--24 specimens from 8
collections at 2 places in Alachua Co.

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

2
Maximum density: . 364/plant at #17; 7.5/m at #75.

Nymphs of this species are extremely difficult to dis-
tinguish from E. signatum nymphs. Only larger, last instar
nymphs could be separated v/ith confidence by counting the
number of spines on the caudal lamellae. Smaller nymphs
were classed n--^ belonging tn tlie Enallagma signatum- pollutum
complex. No water quality preferences for this species were
noted. All but 3 specimens v/ere collected from Camps Canal
east of Micanopy. All xv/ere found between mid-May and

48

mid-tlovember. Since this species has a significant, nega-
tive correlation v/ith 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.
Maximum density: . 35/plant and 35/m^ at #96.
With only last instar nymphs distinguishable from E.
pollutum, this species was collected mainly from November
through February. A strong negative correlation (r=.774,
p=.022, n=9) v/ith 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- pollutum 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/m^ at #102.
\Jater quality preferences: pH , 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.

Tnsect assnciations : llydrocanthus oblongus Sharp,
r=.655, p=.040, n=10.

Young Enallagma nymplis which could be determined as
belonging to either E. pollutum or E. signatum but whose
exact species remained unknown due to their small size and

h'-j

undeveloped dingnostic characters were placed in this group.
This species complex V7as found in shallower water which was
high in chlorides and potassium and had a high pH. It was
correlated v/ith the presence of H. oblongus . These nymphs
were collected throughout the year.

9. Ischnura posita (llagen) -- 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; SO/m^ at #69.

Water quality preference: nitrates, r=-.477, p=.045,
n=18.

Insect associations: Belostoma spp . nymphs, r=.779,
p=.008, n=10; Pelocoris femoratus (Palisot-Beauvois) , r=.806,
p=.000I, n=22; Ranatra austral is }Iungerford, r=-.7 74, p=.041,
n=7.

VJhile it x^7as only the fourth m.ost numerous in specimens
collected, I. posita was found in 53.47. of my collections,
more than any other species. It was present throughout the
vear hut reached peak density in the spring. It appears to
prefer less eutrophic waters, i.e., those with less nitrates.
It was generally found when Ranatra australis was present in
low numbers and vjhen Belostoma spp. nym.phs were abundant.
There V7as an extremely significant correlation with Pelocoris
femoratus, with P. femoratus being collected only 7 times in

50

Lon

the absence of I. posita. . The strength of this associatii
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-
ship between these two species. The Ischnura ramburii re-
corded by O'Hara (1961) may have been misidentif led 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 Westf all--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.

r'aximum density: 1.67/plant at #39; 70/m"- at #97.

Insect associations: Brachyvatus seminulum LeConte ,
r=_.9L8, p=.028, n=5; Scirtes larvae, r=-.886, p=.045, n=5 .

The second most numerous odonate in my collections,
T. byersi was found in 29 . 57o of my collections, which ranked
it n;; teiU h in jiumber of collections in which it was present
and sixth in total number of specimens. It was found through-
out the year. Florida specimens of this species were thought
to be Telebasis salva until V.festfall described T. byersi in
1957. I'Jhile there are significant negative correlations
with 2 species of aquatic beetles, no v/ater quality prefer-
ences were noted. Since T. byersi keys out as belonging to

51

the genus Nehalenia in most keys, it is probable that the
Mehalenia recorded by Katz (1967) from v;aterhyacinth roots
was really T. byersi .

Anisoptera (Dragonf lies) Nymphs

With 275 specimens (5% of the total specimens collected) ,
this suborder v/as not as numerous as the dams elf lies and made
up only 26.7% 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. A% of the 122 specimens found at collection
#102.

O'Hara (1961) collected 5 species of Anisoptera from
waterhyacinth-covered canals while Katz (1967) records 8
different species. I collected 4 species in common with
O'Hara but did not find any Bra chyme sia (=Cannacria) gravida
(Calvert) . Wliile I collected only 3 species in common with
Katz, several of her determinations are suspect, e.g^. Dythemis
sp. and Nannothemis bella are both thought to be found in
Florida only in the western panhandle region.

Aeshn idae

VJith only 5 specimens in 3 species, this family was rarely
found beneath v;a terhyacinl iis and neither O'Hara (1961) nor Katz
(1967) record any aeshnid species.

52

11. An ax Junius (Drury)--l specimen collected at Camps
Canal in December 1973.

Collection: 42.
Density: .31/plant.

12. Boyeria vinosa (Say)--l specimen collected in a
stream in December 19 73.

Collection: 47.
Density: .026/plant.

13. Coryphaeschna ingens (Rambur)--l specimen collected
at Camps Canal in December 1973.

Collection: 42.

Density: .031/plant.

Byers (1930) records this species from waterhyacinth .

14. Nasiaeschna pentacantha (Rambur)--3 specimens
from 3 collections at 2 locations in 2 counties.

Collections: 35, 45, 50.

Maximum density: .0 77/plant at #4 5.

Cordulidae

-'-^- Tetragoneuria cynosura (Say) --2 specimens from 2
collections at a small stream in Alachua Co.

Collections: 27, 87.

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

This genus is now considered by some authorities to be
part of E£itheca. Both O'llara (1961) and Katz (1967) col-
lected Tetragoneuria sp. from waterhyacinths .

53

Gonipliidae

Most members of this family are burrowing forms and
are rarely found beneath waterhyacinths .

16. Aphyla williamsoni (Gloyd)--l specimen collected
at Camps Canal on 29 May 1974.
Collection: 73.
Density: .997/plant or 1/m .

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 vyhere 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.

Libe llulidae

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. 77=
were members of this family.

17. Ery themis simplicollis (Say) --36 specimens in 9
collections at 9 locations in 4 counties.

Collections: 2, 3, 13, 21, 45, 47, S3, 86, 87.

2
Maximum density: .615/plant at #45; 40/m at #85.

This species was not usually very abundant in my col-
lections, but 18 of the 29 odonate nymphs found by O'Hara

54

(1961) in v/aterhyacinth mats were E. simplicollis . My
specimens were all collected in late summer or during Decem-
ber .

18. Miathyria marcel la (Selys)--116 specimens from 10
collections at 9 locations in 6 counties.

Collections: 5, 7, 20, 30, 31, 47, 75, 88, 100, 102.
Maximum density: 5/plant or 400/m2 at #102.
VJhile this was my most abundant Anisoptera nymph, 69%
of all the specimens of this species were found in collection
#102. O'Hara (1961) recorded this 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-
t\\'een June and December.

19. Pachydiplax longipennis (Burmeis ter) -- 111 specimens
in 30 collections from 15 locations in 8 counties.

Collections: 2, 4, 7, 13, 29, 30, 31, 35, 36, 38, 42,
45, 47, 51, 53, 54, 56, 57, 59, 70, 75, 79, 83, 85, 87, 88,
94, 95, 97, 103.

Maximum density: .391/plant at #51; 31. 5 /m^ at #85.
Uater quality preference: iron, r= . 900 , p=.014, n=6 .
Insect associations: Pelocoris fcmoratus , r=-.554,
p=.05O, n=13.

55

VJhile not overly abundant at any location, this species
v;as widely distributed, and among the odonates, only Ischnura
posita was found in more collections. Among all my specimens,
P. longipennis 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 f emoratus . Not surprisingly, both O'Hara (1961) and
Katz (1967) report this species from their waterhyacinth col-
lections .

20. Perithemis tenera (Say)--l specimen collected at
Lake Lawne in Orlando on 13 July 1973.

Collection: 26.
Density: .033/plant.

Macromiidae

Frequently considered as a subfamily of the family
Libellulidae , nymphs of this family are bottom sprawlers
and v/ere infrequent in my collection.

21. Macromia 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.

56

Hemiptera (True Bugs) --Adul Ls and Nymphs

VJhile aquatic hemipterans, with 504 specimens, com-
prised only 9 . 2?o 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. I'Jhile 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 Hemiptera, with Notonecta sp . the
only one which I did not also collect.

Since all aquatic Hemiptera (except t!ie Corixidae) are
predaceous, their presence should be associated with that of
a suitable prey organism, most probably the amphipod Hyalella
azteca.

Belostomatidae (Giant Water Bugs)

Uith 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 26.67, of the 60 specimens in collection #54. Both O'Hara

57

(1961) and Katz (1967) as well as Hansen et £l. (1971) men-
tion collecting Delostorna 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,
103.

Maximum density: . 18/plant or lO/m^ at #94.
Adults of this species were never abundant, more than
one specimen being collected only once. Ily 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 v/aterhyacinth-covered '-.'aters.

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 #37; 10/m^ at #94.
Most of my specimens (65%) came from a drainage culvert
along Interstate 75 north of Micanopy. Except for 2 speci-
mens found in February, all were collected from June through
tlovember .

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.

Maximum density: .83J/plant at #22; IS/m^ 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.

24. Lethocerus uhleri (Montandon) --1 specimen col-
lected at Camps Canal in October 1973.

Collection : 35 .

Density: .031/plant.

Corixidae (Water Boatmen)

All specimens were collected at Otter Creek, Levy Co.,
in July of 1973.

Collections: 20, 21.

Maximum density: . 154/plant at #21.

VHiile the 2 adults appear to be Trichorixa sp . , the
other specimen is a nym.ph and cannot be keyed. Members of
this family are rare among waterhyacinths and were all col-
lected at one location. They were not reported by either
O'Hara (1961) or Katz (1967).

Gerridae (VJater Striders)

These surf ace- film, forms were rare in my collections.
Although present at the collection sites, they generally
seem to prefer more open v;ater than that found between water-
hyacinth plants. Only a total of 6 specimens of this family
vjere collected.

59

26. Gerris canaliculaCus (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. Limnogonus 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 Linmogonus sp . in water-
hyacinth roots.

28. Trepobates sp.--only 1 specimeii collected with
L. hesione (above) .

Collection: 21.
Density: .977/plant.

Unidentified gerrid nyniphs--3 specimens from 3 locations
in 2 counties .

Collections: 20, 33, 75.

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

Hebridae (Velvet IJater 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 A species V7ere collected, all of them in Alachua
Co. Katz (196 7) records Hcbrus sp . from waterhyacinths in
the Withlacoochee River.

29. Hebrus burmeisteri (L. & S.)--4 specimens from 3
locations in Alachua Co.

60

Collections: 30, 54, 72.

Maximum densit}^: .971/plant at #54; 1 . O/m^ at #72.

30. Hebrus consolidus Uhler--5 specimeiis from 5 loca-
tions in Alachua Co.

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

Maximum density: .048/plant at #49; 1.67/m^ at #70.
All my specimens of this species were collected between
January and July.

31. Merragata brevis Champion- -only 1 specimen from
Camps Canal in May of 1974.

Collection: 70.

Density: .014/plant or 1.66/m^.

32. Merragata brunnea Drake--ll specimens in 4 collec-
tions from 3 locations in Alachua Co.

Collections: 15, 29. 75, 85.

Maximum density: .083/plant at #15, 1.5/v?- at #85.
All my specimens of this species vjere collected during
the summer months .

Hydr ometridae (IJater Measurers)

With only 18 specimens distributed between 2 species,
this family was never particular I}/- abundant. Katz (1967) re-
ports finding them in 2 of her collections.

33. Hydrometra myrae Bueno--ll specimens from 7 collec-
tions, all at Camps Canal.

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

2
Maximum density: .235/plant or 20/m at #99.

61

My most common hydrometrid, 11. myrae is considered
"... the most prevalent Ilydrometra in the state" (Herring 194;
p. 113). My specimens were collected between April and Novem-
ber .

34. Ilydrometra wileyi Hungerf ord-- 3 specimens in 2 col-
lections from 2 counties.

Collections: 27, 107.

9

Maximum density: .125/plant or 10/m'^ 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.

Maximum density: .077/plant at #21.

Mesoveliidae (I'Jater 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 waterhyacinths .

35. Mesovelia mu 1 s an t i VJhite--15 specimens in 10 col-
lections from 7 locations in 4 counties.

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

Maximum density: .091/plant at #94; 10/m^ at #85.

All the adult mesoveliids I collected belonged to this
species. Herring (1951b) records this species from

62

watcrliyacinths . 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.

Mesovelia 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 #38; 15/m^ at #95.
Insect associations: Myxosargus spp . , r=-.746, p=.013,
n=10.

Although all mesoveliid nymphs key out to M. amoena
Uhler, I classed all these nymphs simply as Mesovelia sp .
Dr. Jon Herring at the National Museum considered most (if
not all) of my mesoveliid nymphs to be M. amoena, but I con-
sider this unlilcely since I collected no M. amoena adults
but many M. mulsanti adults. There is a strong positive cor-
I'elation vn'^tli the presence of stratiomyid larvae, Myxosargus .
These nymphs were collected throughout the year.

Naucoridae (Creeping Water Bugs)

Uaucorids were not only the best-represented hemipteran
family, being present in 43 collections, l)ut it was also the
most numerous hemipteran family, with 194 specimens making up
38.5/'. of heniipterans collected and 3 . 57o of the total insects.
Both (J'llara (1961) and KaL---. (1967) record this family, which
is represented in the eastern U. S. by 1 genus and 3 species.

63

36. Pelocoris ballus La Rivers- -10 7 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/m^ at #72.
VJater quality preference: potassium, r=- . 739 , p=.009,
n=ll.

Insect associations: Pelocoris f emoratus , 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. f emoratus by La Rivers,
P. balius has been elevated to species rank by me since the 2
species v/ere collected together 17 times.

P. balius is associated with low levels of potassium,
with P. f emoratus , Hydrovatus larvae, and with Suphisellus
puncticollis . It is generally found in waters where the num-
bers of S. insularis are low. It was collected throughout
the year, with over 797o of the specimens coming from Camps
Canal .

37. Pelocoris femora tus (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, Q9, 102.

Maximum density: .205/plant or 25/m^ at il^lO.

64

Insect associations: Ischnura posita , r=.806, p=.0001,
n=22; Pach^/diplax longipennis , r=-.554, p=.050, n=I3; Peloc-
oris balius , r=,471, p=.057, n=17; Pvanatra 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) v/ith the damselfly nymph Ischnura posita, with P.
f emoratus being found only 7 times (out of 29) in the absence
of I. posita. P. f emoratus is negatively correlated with the
anisopteran P achy dip lax longipennis and with the nepid Ranatra
australis . There is a strong correlation (r=-.601, p=.01,
n=17) with plants having fewer leaves. Over 837o of the speci-
mens were collected at Camps Canal.

Nepidae (Water Scorpions)

With 52 specim.ens 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.
However, they were sometimes extremely abundant locally,
with collection #75 averaging 75 specimens/m"^ . Neither O'Hara
(1961) nor Katz (1967) records any water scorpions from their
collections .

38. Ranatra 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: .484/plant or 75/m at #75.

65

Water quality preference: nitrates, r=.747, p=.033,
n=8.

Insect associations: Ischnura posita, r=-.774, p=.041,
n=7; Pelocoris f emoratus , r=-.920, p=.010, n=6.

Herring (1951a) records this "... the most prevalent
Ranatra in Florida" (p. 18) from waterhyacinths . This species
was generally found in shallow water which was high in nitrates
It is negatively associated with the presence of either I.
posita or P. f emoratus . Almost 437o of my specimens were col-
lected 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 Decemher.

39. Ranatra buenoi Hungerford--6 specimens collected
only at Camps Canal, Alachua Co.

Collections: 70, 73, 94, 95.
Maximum density: .20/plant or IS/m'"' at #95.
This relatively rare species was collected only at
Camps Canal in May, October, and November.

40. Ranatra nigra Herrich-Schaef f er- -11 specimens from
2 collections in 2 counties.

Collections: 102, 103.

o

Maximum density: .625/plant or 50/m*" at #102.

Although it was collected only in December at 2 loca-
tions in SouLli Florida, it was quite abundant at Prairie
Creek, averaging 50 water scorpions per square meter.

66

Pleidae (Pygmy Back Sv/iinmeis)

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.

Al. Neoplea striola (Fieber)--22 specimens in 9 col-
lections from A locations from 2 counties.

Collections: 3, 18, 36, 53, 71, 75, 87, 88, 97.
Maximum density: . 50/plant or 25/m'- at #97.
Water quality preference: potassium, r=.910, p=.032,
n=5.

Formerly knoxvrn 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-
though they were found throughout the vear, 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 tlian 2 specimens
when found, but it was well-represented, being present in
over 307o of my collections. Thus, although they comprise
less than l?o of the total insects collected, their contribu-
tion to the diversity of the collection is important.

42. Microvelia borealls Bueno--25 specimens in 15 col-
lections from 12 locations in 4 counties.

Collections: 1, 2, 15, 16, 19, 21, 23, 24, 25, 34, 43,
44, 53, 72, 75.

67

Ilaximum density: .09'j/plant at #16; 2.5/m^ at #75.

Katz (1967) recorded this genus in her collections.

43. Velia brachlalis 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.

Maximum density: . 182/plant at #38; 10/m^ at #103.

Velia is negatively correlated with number of leaves
per plant (r=-.933, p=.020, n=5) .

Almost 7 3% of the specimens came from Camps Canal. Katz
(1967) reports this genus from her collections.

Trichoptera (Caddisf lies) Larvae

Only 16 caddisfly larvae belonging to 2 species were
found during this study and 15 of these came from the same
location. Although from my collections Trichoptera would
appear to be rare, O'Hara (1961) reports a probable 3 differ-
ent, unidentified species while Katz (1967) recorded 5 dif-
ferent groups in her survey.

Leptoceridae

44. Oecetis prob . cinerascens (Hag.)--6 specimens in 4
collections from 2 locations in Alachua Co.

Collections: 3, 35, 50, 87.

o
Maximum density: .05/plant or 2.5/m 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.

68

Psychoniyidae

'^5. 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; A/m^ at #74.

Insect associations: Chironomus attenuatus, r=-.873,
p=.054, n=5.

All my sj:)ecimens were collected between May and Septem-
ber at Camps Canal. Katz (1967) recorded this genus from
all her collections.

Megaloptera

A total of 17 specimens, all belonging to the same
species, were collected. I have found no references for any-
one reporting tliis group from waterhyacinths .

Corydalidae

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/m^ at #69.

Water quality preference: nitrates, r=-.697, p=.055,
n=8.

The larvae of this species can be identified by the
yellow stri.pe on the dorsum, as noted bv Cuyler (1958). The
larvae I collected were correlated with low levels of nitrates
in the v/ater. All but one specimen came from Camps Canal.

69

ColeopLera (Beetles)

With 2,498 specimens (45.5% of the total specimens),
the beetles were my most abundant ordei* 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, 14.87o
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, which 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 misidentif ied a noterid such as Colpius inf latus or a
dytiscid such as Hydrovatus sp .

Katz (1967) presents 45 different genera of beetles.
At least 10 of her genera, however, belong to families such
as Anthicidae, Curculionidae , Scaphidiidae , Scolytidae and
Stapliylinidae . which, are not kno\^m to have truly aquatic mem-
bers in Florida. By trulv aquatic, I mean insects which have
at least one life stage in or on the water. She also lists

70

Limnichus sp . , which is only known from southwestern U. S.
and Helophorus , 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
vzould be expected in the lentic situations in which water-
hyacinths are found.

47. Pelonomus obscurus gracilipes Chevrolat--3 speci-
mens from 3 collections at Camps Canal, Alachua Co.

Collections: 89, 91, 94.

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

Katz (1967) reports collecting Pelonomus sp .

Dytiscidae (Predaceous VJater Beetles)

With 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 system was very great,
especially since they comprised only 13.7% of the total
specimens collected and 30.1% of the beetles collected.

71

Of the d\^tiscid subfamilies, the Hvdroporinae are
definitely a characteristic component of waterhyacinth root
beetle fauna. The Hydroporinae comprised 89.5% of my dytis-
cid specimens and of the 12 genera knol^m from Florida, I
collected 10.

Of the dytiscid specimens, 132 (17.67^) were larvae. Of
the beetle families, only the helodids had more larvae.

Katz (1967) lists the following dytiscid genera from her
waterhyacinth root collections: Bidessus , Laccodytes , Hydro-
vatus , Laccophilus , Orcodytes (=Hydroporus in part?) , Celina,
Copelatus , Derovatellus , Hygrotus , Coptotomus and Cybister .
Of these genera I collected all but Laccodytes , Derovatellus
and Hygrotus . O'Hara (1961) found no dytiscid larvae and
found adults x^7ere relatively rare.

48. Anodochilus exiguus (Aube)--l specimen collected at
Otter Creek, Levy Co., in July.

Collection: 21.
Density: .077/plant.

49. Bidessonotus longavalis (Blatchley) --1 specimen
collected at Camps Canal, Alachua Co., in July.

Collection: 18.

'^^ ■ Bidessonotus pulicarius (Aube)--7 specimens in 5
collections at 2 locations in Alachua Co.
Collections: 36, 75, 93, 94, 95.

o

Maximum density: .182/plant or 10/ra'^ at #94.
Five of my specimens \jere collected in October while
one each were found in June and November.

72

Eidessonotus spp . femaies--4 specimens in 4 collections.

Collections: 2, 34, 71, 74.

2
Maximum density: .026/plant or 5/m at #71.

Since some species of Eidessonotus can be identified
only by the shape of the aedeagus , some unidentifiable fe-
males of the genera are placed in this classification.

51. Bidessus f lavicollis (LeConte)--4 specimens in 2
collections in Alachua and Orange Cos.

Collections: 3, 96.

Maximum density: .15/plant or 15/m at #96.
My specimens were collected in August and November.
This species is usually found in algal mats.

52. Erachyvatus seminulus (LeConte) - -79 specimens in
10 collections from 6 locations in 2 counties.

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

2
Maximum density: 1.163/plant or 142. 5/m at #85.

Insect associations: Telebasis byersi , r=-.918, p=.028,
n=5.

This genus was once considered as a subgenus of Eidessus .
A single collection at the Styx River in August accounted for
72?o of my specimens of this species, which reached a density
of over 140 per square meter. All of my specimens were col-
lected from May through October, with the majority (85%)
being collected in August.

53. Celina angus tata Aube--6 specimens in 5 collections
from 5 locations in 3 counties.

Collections: 15, 19, 29, 77, 79.

73

Maximum density: .133/plant and 5/m^ at #77 and #79.

All my specimens were collected in June or July.

^'^- 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/m^ at #92.

Insect associations: Colpius inClatus (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 Decemiber in South Florida.

55. Celina slossoni Mutchler--3 specimens from 3 loca-
tions in Alachua Co.

Collections: 29, 34, 92.

2
Maximum density: .077/plant or 5/m 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.

2

Maximum density: . 333/plant at #37; 15/m at #86.

Insect associations: Hydrocanthus larvae, r= . 840 ,
P=.009, n=8; Folypcdilum illinoense (Malloch), r=.878,
p=.021. n=6.

74

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 common 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--ll speci-
mens in 8 collections from 5 locations in 2 counties.

Collections: 1, 3, 7, 37, 52, 74, 81, 89.

Maximum density: 1.66 7 /plant at #3 7; 3.33/m^ at #89.

All my specimens of this species were collected from
June through October except for one specimen collected at
Lake Alice in February.

57. Copelatus 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 lO/m"^ at #94.
Found from July through December, this species is known
to prefer areas v/ith accumulations of organic debris.

58. Coptotomus inter rogatus obscurus Sharp--3 specimens
from 3 locations in 2 counties.

Collections: 17, 27, 103.

2
Maximum density: .032/plant or 5/m at #103.

Both of my Alachua Co. specimens v;ere collected in July

while the one from South Florida was found in December.

75

^^- Cybister frimbiolatus 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--ll specimens in 7 collections from
6 locations in 3 counties.

Collections: 33, 47, 75, 78, 85, 88, 99.

9

Maximum density: .073/plant or 7.5/m at #75.

Cybister sp . larvae were collected from June through
December with most (45.470 being found in June.

60. Desmopachria grana (LeConte) complex- -27 specimens
in 16 collections from 11 locations in Alacliua Co.

Collections: 1, 11, 14, 15, 19, 23, 27, 34, 37, 39, 41,
52, 57, 91, 94, 95.

Maximum density: .454/plant or 25/m^ at #94.

Insect associations: Myxosargus sp . , r=.845, p=.034,
n = 6 .

This small dytiscid, characteristic of detritus pond
conditions, was well-distributed throughout Alachua Co.,
being prese?Tt at 11 of the 16 different areas I collected.
I collected this species throughout most of the year, with

76

the exception of the spring months. It was most abundant in
my October collections, with 38% of the total Desmopachria
collected.

61. Hydroporus dixianus Fall--2 specimens collected
together at Lake Talquin, Gadsden Co.

Collection: 95.
Density: .1/plant or lO/m"^.

Only one other specimen of this rare species has been
recorded from Florida (Young 1955) .

62. Hydroporus 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/m at #83.

Of my specimens, 10 were collected during the summer and
one in January. Most (737,) were collected at Camps Canal in
Alachua Co.

^■^ ■ Hydroporus lynceus Sharp- -1 specimen collected in
November at Lake Talquin, Gadsden Co.

Collection; 96.

2

Density: .05/plant or 5/m .

64. Hydroporus vittatipennis Gemminger & Von Harold- -

1 specimen collected in November at Lake Talquin, Gadsden Co.

Collection : 95 .

2

Density: .05/plant or 5/m .

65. Hydrovatus compressus Sharp--276 specimens in 36
collections from 15 locations in 6 counties.

n

Collections: 12, 23, 24, 25, 26, 29, 30, 32, 33, 36, 37,
39, /(I, 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; llO/m"^ 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 insular is (Sharp),
r=.548, p=.006, n=24.

This species was extremely well represented, being found
in 417o 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 more abundant than H.
compressus . If one of these species were present, in 677o
of tlie cases the other would be present also. Lake Alice
accounted for 63.67o of the specimens, v/hile Camps Canal pro-
vided an additional 17%. This species was abundant especially
during late vrintcr and was collected throughout the year.

66. Hydrovatus inexpectatus Young- -1 specimen collected
in July at Camps Canal, Alachua Co.

Collection: 80.

Density: .013/plant or 1/m .

This species is very similar to H. compressus and more
specimens may be mixed in with that species. However, Dr.
Frank Young, who described the species (Young 1963) , examined
all my specimens and believes that my determinations are cor-
rect .

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.

2
Maximum density: .667/plant at #37; 40/m at #86.

Insect associations: Fhaenotum exstriatus Say, r=.781,

p=.013, n=9; riesonoterus addendus (Blatchley) , r=-.837, p=.038,

n=6.

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 vjith the presence of the hydrophilid Fhaenotum exstria-
tus. The conditions vjhich favor the presence of the noterid
Mesonoterus addendus would seem to inhibit the presence of
H. peninsularis . H. peninsularis appeared to be most abun-
dant in July, during which 30 , 87o of my specimens were collected.

Hydrovatus 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.

79

0

Maximum density: . 194/plant at #55; 5/m at #75.

Although Hydrovatus larvae are correlated (r=.912,
p=.031, n=5) with higher v/ater temperatures, they were found
throughout the year.

68. Laccophilus gent ills 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.

2

Maximum density: . 2/plant or 10/m 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 sjiecimens in 9 col-
lections from 4 locations in 3 counties.

Collections: 38, 45, 75, 91, 92, 94, 95, 101, 102.

9

Maximum density: . 188/plant or 15/m'' at 7#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.

Laccophilus sp . larvae- -4 specimens from 4 locations in
Alachua Co.

Collections: 12, 27, 29, 33.

Maximum density : . 062/plant or 3 . 33/m'- at #88 .

80

All the Laccophilus larvae were collected during the
summer months .

70. Liodessus afflnis (Say) --2 specimens from 2 loca-
tions in 2 counties.

Collections: 18, 48.

Maximum density: .026/plant at #48.

Liodessus \^as previously considered a subgenus of
Bidessus .

''!■ 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. Mat us ovatus blatchleyi Leech- -1 specimen collected
in June at a pond in Alachua Co.

Collection: 11.

Matus sp. larvae--2 specimens collected from 2 locations
in Alachua Co. during June and July.
Collections: 11, 23.
Maximum density: .017/plant at #23.

73. Neobidessus pull us f loridanus (Fall)--l specimen
from Lake Alice, 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 ditch in Alachua Co.

81

Collections: 33,

40.

riaximum dens i ty :

.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. obniger 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.

riaximum density: .469/plant or 25/m" 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 waterhyacinths along the
shore of Lake Okeechobee.

Insect associations: Hydrovatus peninsularis , r=.681,
p= . 043 , n=9 ; Phaenotum exstriatus , r= . 875 , p= . 010 , n=7 ;
Suphisellus gibbulus (Aube) , r=.744, p=.021, n=9 ; Myxosargus
sp. , r=.889, p=.017, n=&.

Pachydrus larvae were found in waters having high iron
content and frequently having populations of the dytiscid H.
peninsularis , the hydrophilid P. exstriatus , the noterid S.
gibbulus , and the stratiomyid Myxosargus . Over 557o of the
specimens came from Camps Canal, and all but 2 specimens were
collected between May and October.

'^- Thermonectus basillaris (Harris) --1 specim.en col-
lected in July at a drainage? ditch in Alachua Co.
Collection: 22.

82

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/m^ at #86.

Some dytiscid larvae could be identified only to the
tribe level. The tribe Bidessini has 5 genera: Bidessus
(sensu latu) , Bidessonotus , Brachyvatus , Desmopachria and
Pachydrus .

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 waterhyacinth root collections.

77. Dubiraphia quadrinotata (Say) --3 specimens in 2
collections from 2 counties.

Collections: 18, 103.

Maximum density: .032/plant or 5/m at #103.

83

Gyrinidae (VJhirligig Beetles)

Only 3 specimens from 3 different species were collected
from waterhyacinth roots. I^Jhile 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--! specimen at Otter Creek,
Levy Co . , in July.

Collection: 21.
Density: .077/plant.

Katz (1967) reports this genus from several of her col-
lections .

79. Gyrinus elevatus LeConte- -single specimen collected
at Peace River, Hardee Co. , in December.

Collection: 102.

2
Density: .063/plant or 5/m .

80. Gyrinus woodruf f i 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 waterl;vacinths nrefor.

84

Haliplidae (Crawling Water Beetles)

Only 12 specimens in 3 different species in one genus
were found. VJhile not common, they were not truly rare in
waterhyacinth roots. Since adults crawl and swim along the
bottom, they probably only occasionally hide in waterhyacinth
roots. Katz (1967) recorded Peltodytes sp . from 2 of her
collections. O'Hara (1968) found haliplids locally abundant
but recorded only the genus Haliplus, whlcli 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. Peltodytes f loridonsis Mathe.son--6 specim^ens 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 oppositus Roberts--3 specimens from 3
locations in 2 counties.

Collections: 38, 71. 102.

Maximum density: .063/plant or 5/m^ at #102.

Helodidae (^Cyptionidae) (Ma r s h B e e 1 1 e s ) Larvae

The Helodidae, sometimes also Icnov/n as the Cyphonidae,
consisted of 138 larvae belonging to 2 genera and at least

85

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 Florida State Collection of
Arthropods. U^ile the adults enter the water only for ovi-
position or escape, the larvae were sometimes abundant in
closely packed, detritus-filled mats of waterhyacinths .
Katz (1967) collected specimens from this family but reports
Cyphon, a genus which I did not find, and does not mention
the genera I collected.

84. Ora hyacintha 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 waterhyacinths on the shore, this species could be dis-
tinguished from my other species of Ora only in the adult
stage. The species name seems especiallv appropriate in
vievj of the abundance of what are probably larvae of this
species in some wa terhyacinth habitats.

85. Ora trobcrti (Cuer.) (adults reared from larvae) --
3 specimens from 2 locations at a drainage ditch in Alachua
Co.

86

Collections: 33, 37.
Maxiinuin 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 undescribed 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 of 0. hyacintha
from the larvae of 0. troberti 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. hyacintha, the smaller larvae could be either species.
Ora sp . larvae were associated with waterhyacinths growing
in deeper water. All my Ora larvae cam.e from the same loca-
tion, a drainage ditch off of 1-75 north of Micanopy in
Alachua Co., where they were the most frequently collected
and second most numerous insects found. All but 10 speci-
mens v/ere collected in the fall and early winter months.

86. Scirtes spp . adults-- single specimen from drainage
ditch in Alachua Co. in September.
Col lection : 33 .
Density: .019/plant.

A single Scirtes adult was found. Although adults are
not truly aquatic, since tliey sometimes enter the water this
specimen was not excluded from my collection.

87

Scirtes sp. larvae--4i 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 SO/m^ at #90.

Insect associations: Telebasis byersi, r=-.886,
p=.045, n=5.

Scirtes larvae were found at many more different loca-
I i"Ms 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) (Minute Moss Beetles)

These tiny beetles, less than 1% 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'Hara (1961) nor
Katz (1967) records any members of this family.

87. Hydraena marginicollis Kiesenv7etter--12 specimens
from 7 collections at 5 locations in 2 counties.

Collections: 2, 3. 21, 33, 34, 42, 53.

Maximum density: .154/plant.

Hydrochidae

Considered by many to be a subfamily of the hydro-
philids, 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 Maryland.

88. Hydrochus inaequalis LeConte--5 specimens from 4
collections at Camps Canal, Alachua Co.

Collections: 38, 53, 91, 94.

Maximum density; .091/plant or 5/m at #94.

89. Hydrochus prolatus Hellman- -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. Hydrochus wood! Hellman--2 specimens in 1 collec-
tion from Camps Canal in July.

Collection; 17.
Density: .061/plant.

Hydrophilidae (Water Scaven ger Beetles)

With only 131 specimens, 17 of which were larvae,
hydrophilids were not one of my most abundant families.
VJhile only 3 of the 13 species were represented by 10 or
more individuals, tiiey were fairly well distributed, with
hydrophilids being found in 40 collections. O'Hara (1961)
reports collecting no larvae and that hydrophilid adults

89

were rare. Of the Hydrophiiidae genera listed by Katz (1967)
from waterhyacinth roots, I collected: Faracymus , Enochrus ,
Tropisternus , Phaenotum, Berosus , Helobata, Helochares and
Crenitulus . I additionally collected Cercyon, Derrallus and
Hydrobiomorpha, while she also found Helophorus and Laccobius .

92. Berosus 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 May at Camps Canal, Alachua Co.

Collection: 73.

Density: .008/plant or l/m^.

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 xvas my third most numerous hydrophilid, but two-thirds
of my specimens were in collection #33, with the 1-75 drain-
age ditch supplying 787o of the specimens. All were collected
from June through 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 lO/m^ 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/m 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.

9

Maximum density: . 353/plant or 30/m" at #70.

This species, a detritus pond inhabitant, was my second
most abundant hydrophilid and was tied in the number of col-
lections in which it was found. All my specimens were col-
lected between May and December, with over half coming from
Camps Canal .

91

98. Enochrus perplexus (LeConte)--A specimens from 2
collections at 2 locations in Alachua Co.

Collections: 16, 94.

Maximum density: .273/plant or 15/in at #94.
Enochrus sp. larvae--5 specimens from 4 collections at
3 locations in 2 counties.

Collections: 15, 30. 51, 79.

Maximum density: .087/plant at #51; 5/m^ at #79.

99. Helobata striata (Brulle)--2 specimens in 2 collec-
tions at 2 locations in Alachua Co.

Collections: 3. 34.

Maximum density: .04/plant.

Blatchley (1932) has recorded this species from leaves
of pickerelweed, Pontederia, as has Young (1954). These
flattened insects stick limpet-like to submerged objects.
This type of behavior may cause them to appear more rare
tlian they really are, since they might be difficult to dis-
lodge by mere v/ashing of waterhyacinth roots.

100. Helochares sp. larvae--l specimen collected in
June at a small pond in Hardee Co.

Collection: 78.

Density: .013/plant; 1.67/m2.

101. ilydrobiomorpha casta (Say) adults- -7 specimens in
4 collections at 3 locations in Alachua Co.

Collections: 30, 71, 94, 95.

Maximum density: .273/plant or 15/m2 at #94.
This genus is frequently referred to as Neohydrophilus .
These fairly large insects were never very common in my

92

collections. However, this species is positively correlated
with several measures of diversity, indicating that it is
found in high diversity situations.

Hydrobiomorpha casta larvae- -2 specimens from 2 collec-
tions at 2 locations in Alachua Co.

Collections: 24, 89.

Maximum density: .031/plant or 1.67/m2 at #89.

102. Paracymus despectus (LeConte) - -single specimen
collected in December at a roadside canal in Palm Beach Co.

Collection : 46 .
Density: .043/plant.

103. Phaenotum exstriatus (Say) --33 specimens in 16
collections from 5 locations in 2 counties.

Collections: 3. 11, 15, 17, 22, 31, 35, 37, 69, 79,
86, 89, 91, 93, 94, 95.

Maximum density: . 20/plant at #95; 40/m at 7^-79.

Insect associations: Hydrovatus peninsularis , r=.781,
p=.013, n=9; Pachydrus larvae, r=.875, p=.010, n=7.

This species, a member of the subfamily Sphaeridinae
v/hose members are generally not considered aquatic, was my
most numberous hydrophilid and tied for being represented
in the most collections. It constituted over 257c, of the
hydrophilids collected. This species is strongly correlated
with the presence of two dytiscids, Hydrovatus peninsularis
and the larvae of Pachydrus. Over 60^/0 of my specimens were
collected at Camps Canal and all were collected from mid-June

93

through early November. This would coincide with the build-
up of detritus as waterhyacinth mats senesced.

104. Tropisternus blatchleyii D ' Orchymont--8 specimens
from 3 collections at Camps Canal, Alachua Co.

Collections: 3, 18, 74.

Maximum density: .008 /plant or 1/m at #74.

Tropisternus sp . larvae--6 specimens in 3 collections
from 2 locations in Alachua Co.

Collections: 22, 89, 90.

Maximum density: .22/plant at ,#22; S/m^ at #90.

Noteridae (Burrowing Water Beetles)

With 1,432 specimens, 82 of which were larvae, the
noterids were easily my most abundant insect family and can
be considered as a characteristic component of waterhyacinth
fauna. Comprising 57.3% of all the beetles collected and
over 267, of all the insects collected, this family was repre-
sented in 847, of my collections, with as many as 174 noterids
being found in a single collection. Of the 10 (or 11, the
status of Suphisellus punctipennis (Sharp) being questionable)
species of noterids known to occur in Florida, I collected
8, all except Hotomicrus manulus (LeConte) and Suphisellus
parson! Young, of which the two types are the only known
specimens. Such relatively rare species as Mesonoterus
addendus (Blatchley) were fairly common in waterhyacinth
roots and the 4 specimens of Pronoterus semipunctatus
(LeConte) which I found more than doubled the known specimens
for the state.

94

O'Hara (1961) amazingly does not report any members
of this family, but I believe that he may have misidentif led
them as Omophronidae . Katz (1967) records all the genera
that I collected if her Pronoterus includes what is now called
Mesonoterus .

105. Colpius inf latus (LeConte) adults--177 specimens
in 23 collections from 6 locations in A counties.

Collections: 3, 18, 22, 31, 33, 43, 44, 50, 71, 72,
73, 74, 81, 84, 89, 91, 92, 93, 94, 95, 97, 99, 102.
Maximum density: 4.6/plant or 230/m2 at #97.
Insect associations: Celina grossula , r=-.934, p=.020,
n=5.

Dr. Paul Spangler at the National Museum believes this
species to be a member of the tropical geiius Suphis . This
species was my fourth most abundant beetle and ranked as my
seventh most abundant species overall. They sometimes
reached very high densities, such as 230 specimens per square
meter of waterhyacinth mat at a roadside ditch in Liberty Co.
They appear to be common throughout the year.

Over 59 . 37o of my specimens came from Camps Canal.
Colpius inf latus larvae--15 specimens in 5 collections
from 3 locations in 2 counties.

Collections: 21, 41, 55, 75, 80.

Maximum density: .154/plant at #21; 12.5/vc?- at #75.
The most distinctive larvae of a nondescript group,
they were collected in mid-summer and early winter.

95

106. Ilydrocanthus obiongus Sharp-- 60 spiecimens in 26
collections from 14 locations in 6 counties.

Collections: 1, 3, 11, 12, 18, 22, 25, 31, 34, 35, 38,

45, 57, 70, 78, 79, 87, 89, 91, 93, 94, 95, 97, 99, 102, 103

2
riaxinium density: 1.00/plant at #45; 20/m at #95.

Insect associations: Caenis diminuta , r=.841, p=.002,
n=10; Enallagma s igna turn- po Hut urn complex, r=.655, p=.040,
n = 10.

H. obiongus did not appear to be quite as abundant as
H. regius but seemed to be more widely distributed, being
collected at more locations. All but 3 of my specimens were
collected from late June through December. H. obiongus
seemed very sensitive, significant at the 0.2% level, to the
population levels of the mayfly Caenis diminuta.

107. Ilydrocanthus regius Young--104 specimens from 36
collections at 8 locations in 3 counties.

Collections: 2, 11, 17, 18, 24, 25, 32, 35, 36, 38,
41, 49, 55, 56, 70, 71, 72, 73, 74, 76, 78, 80, 81, 84, 86,
87, 88, 89, 90, 91, 92, 93, 94, 95, 97, 99.

o

Maximum density: 1.545/plant or 85/m at #94.

Water quality preference: hardness, r=-.476, p=.025,
n=22; nitrates, 4=.423, p=.050, n=22; magnesium, r=.563,
p=.006, n=22.

This species was found to significantly prefer cool
water that was low in liardness and magnesium but which was
high in nitrates. They were comm.on throughout the year but
seemed to become more abundant at Camps Canal during mid

96

fall. This was iny fifth most abundant beetle species and
was tied for second in number of collections in which it
was found.

Hydrocanthus sp. larvae- -24 specimens in 12 collections
fromi 8 locations in 3 counties.

Collections: 1, 23, 26, 52, 73, 79, 81, 82, 86, 86,
87, 91.

Maximum density: .176/plant or IS/m^ at #86.
Insect associations: Celina larvae, r= . 840 , p=.009,
n=8.

These were my second most abundant noterid larvae and
were very significantly associated with the presence of
Celina larvae. I\Tiile one Hydrocanthus larva was collected
in February, all the rest were found between late May and
mid- September .

108. Mesonoterus addendus (Blatchley) -- 70 specimens
in 15 collections from 5 locations in 3 counties.

Collections: 24, 29, 32, 36, 39, 41, 44, 49, 52, 71,
75, 88, 89, 92, 97.

Maximum density: . 762/plant at #49; lO/m^ at #71,
#88, #97.

l-Jater quality preference: alkalinity, r=.831, p=.040,
n^6; liardness, r=.815, p=.048, n=6 ; conductivity, r=.836,
p=.038, n=6.

Insect associations: Hydrovatus peninsularis , r=-.837,
p=.038, n=6.

97

This species was previously considered as Pronoterus
addendus , but Dr. Young (personal cominunication) believes it
closer to Mesonoterus . Members of this species appear to
prefer waters that are alkaline and are high in hardness and
conductivity which, perhaps, are less productive, since there
are negative correlations between this species and some in-
dices of diversity. This species seems to be definitely
associated with waterhyacinths (Young 1954) . Young, in his
study, collected only 2 specimens and none from Alachua Co.
Of my specimens, 65 came from Alachua Co. , with over 957o of
these coming from Lake Alice, where Young frequently col-
lected. This is additional evidence for the close relation-
ship of this species to waterhyacinths, since Lake Alice did
not become infested with waterhyacinths until the mid 1960 's
(Cason 1970). Collected throughout the year, this species
appeared to be more abundant in late fall and early winter.

109. Pronoterus semipunctatus (LeConte) adults--4
specimens from 3 locations in Alachua Co.

Collections: 29, 34, 37.

riaximum density; . 167/plant at y^37.

As of 1954 only 3 specim.ens of this relatively rare
species had been recorded from Florida and none from Alachua
Co. riy specimens were collected in July or October.

Mesonoterus or Pronoterus (?) sp. larvae- -7 specimens
in 4 collections at 4 locations in 2 counties.

Collections: 13, 24, 26, 33.

Maximum density: .061/plant at #24.

98

Since only 2 genera of noterid larvae are definitely
known, Colpius (=Suphis) and Hydrocanthus , these larvae were
identified by means of eliminating the known genera and com-
paring the remaining larval types with the relative abun-
dances of the adults .

110. Suphisellus gibbulus (Aube)--332 specimens from
36 collections at 19 locations in 10 counties.

Collections: 1, 11, 18, 19, 22, 25, 26, 27, 29, 30,
33, 37, 40, 43, 44, 45, 47, 48, 54, 57, 76, 79, 80, 81, 83,
86, 87, 89, 91, 93, 94, 95, 97, 101, 102, 103.

Maximum density: 3.83/plant at #37; 40/m^ at #83.
Water quality preference: chlorides, r=-.504, p=.056,
n=15.

This was my second most abundant beetle species (third
in overall abundance) and was tied with Hydrovatus compressus
and Suphisellus insularis for second overall in the number of
collections in which it was present. Popiilations at the 1-75
drainage ditch north of Micanopy were especially heavy, with
only 2 of my 7 collections from there having less than 20
specimens. This location accounted for over 70% of all speci-
mens of this species. Young (1954) reports of this species:
"One of its favorite haunts is among the roots of water hya-
cinths floating in shallow v;ater" (p. 132). My analyses have
revealed an extremely strong negative correlation (r=-.611,
p=.0001, n-34) with root length. Tlieso beetles definitely pre-
fer waterhyacinth plants v.n' th short roots. As noted in the
introduction, root length appears to be inversely related to

99

the nutrient content of tlu; water, although I found no cor-
relations between this species and some of the coirimon nutri-
ents such as nitrates and phosphates. There were also sig-
nificant correlations with low levels of magnesium and in-
creasing depth of water. I have collected this species
throughout the year except the spring months.

111. Suphisellus insularis (Sharp) --549 specimens in
33 collections at 14 locations in 6 counties.

Collections: 2, 3, 4, 11, 13, 19, 24, 25, 26, 29, 30,
32, 36, 39, 41, 44, 47, 49, 52, 55, 56, 71, 75, 78, 79, 80,
85, 86, 88, 89, 91, 93, 94.

Maximum density: 3.68/plant or 337. 5/m^ at #75.
Water quality preference: potassium, r=.599, p=.039,
n=12.

Insect associations: Pelocoris balius, r=- . 549 , p=.052,
n=13; Hydrovatus compressus , r=-.832, p=.040, n=6 ; hydrocan-
thus sp. larvae, r=-.850, p=.032, n=6.

This was my most abundant beetle species and only a
chironomid exceeded it in total numbers. However, 3 other
beetles exceeded it in the number of collections in which
they were present. It sometimes reached incredible densities,
such as 377.5 per square meter at Lake Alice. The popula-
tions at Lake Alice were consistently heavy, with only 2 of
my 12 collections there having less than 10 S. insularis and
with this location accounting for 76.57o of the total speci-
mens of this species. This species preferred deeper waters
which were high in potassium.. S. insularis had a very strong

100

(i-=-.464, p=.006, n=33) negative correlation with Simpson's
diversity index and could therefore be considered an indi-
cator of low diversity conditions. It was also negatively
correlated with Pelocoris balius , Laccophilus gentilis , and
the larvae of Hydrocanthus . However, it was very strongly
correlated (0.67o level) with the population levels of Hydro-
vat us compressus , my second most abundant beetle species.
This species appears to be abundant throughout the year.

112. Suphisellus puncticollis Crotch--44 specimens in
18 collections from 10 locations in 3 counties.

Collections: 1, 7, 15, 22, 27, 29, 34, 37, 40, 43, 44,
57, 71, 76, 86, 89, 91, 93.

Maximum density: 1.5/plant at #37; 10/m^ at #86.
Water quality preference: potassium, r=.826, p=.043,
n=6.

This species was never particularly abundant, with 9
specimens being the most in any one collection. The 1-75
drainage ditch accounted for 21 of the specimens. S. punc-
ticollis v/as collected throughout most of the year.

Suphisellus (?) sp. larvae--43 specimens in 12 collec-
tions from 9 locations in 2 counties .

Collections: 12, 19, 22, 23, 26, 29, 32, 36, 75, 83,
88, 89.

Maximum density: . 390/plant or 40/m'- at #75.
Suphisellus larvae \7ere my most abundant noterid larvae
and were collected between mid-June and mid-October.

101

Unidentified noterid larvae--3 specimens in November
from Lake Alice, Alachua Co.

Collection: 39.

Density: .143/plant.

These 3 larvae were in too poor condition to be identi-
fied following unsuccessful rearing attempts.

L epidoptera (Moths) - -Larv ae

With only 13 specimens from 10 collections, the larvae
of aquatic Lepidoptera were never abundant and comprised only
0.2% of the total specimens I collected. O'Hara (1961) did
not collect any Leipdoptera larvae. Katz (1968) reports
finding the genera Elophila and Nymphula . Dr. D. H. Habeck
(personal communication) feels that these are misidentif ica-
tions, with Nymphula probably being SZIlJ^J L'if'L obliteralis
(Walker) .

Pyralidae

113. Neargyractis slossonalis (Dyar) larvae--2 speci-
mens from 2 locations in Alachua Co.

Collections: 13, 24.

Density: .030/plant at #24.

The larvae of this uncommon species have been previously
reported only from root hairs of trees growing along banks of
rivers and streams (Habeck, unpublished). My specimens were
collected in June and July.

102

114. Synclita obliteralis (Walker) larvae--ll specimens
in 8 collections from 3 locations in Alachua Co.

Collections: 43, 51, 54, 70, 72, 73, 75, 94.

Maximum density: . 310/plant at #51.

The floating larval cases, usually made from 2 pieces
chewed from a v;aterhyacinth leaf, were often numerous on the
water surface around waterhyacinth plants, but only those
cases recovered after washing the waterhyacinth roots were
collected. S. obliteralis larvae v/ere found sporadically
throughout the year.

Diptera (Flies) --Larvae and Pupae

Represented in 69 collections, the Diptera, with 1,265
specimens, constituted my second most abundant order. Only
33 species in 11 families were present, as compared to the
64 species in 10 families of aquatic Coleoptera. The chiro-
nomids, with 1,046 specimens, were by far the most abundant
Diptera and constituted 82.7% of the Diptera and 19.1% of
all insects collected. Both O'Hara (1961) and Katz (1967)
found chironomids to be their most abundant insect group.
Only 2 other Diptera families, the Culicidae and Stratiomyi-
dae, were represented in my collections by more than 9 speci-
mens .

Ceratopogonidae ( Bit ing Midges )

These tiny, almost translucent larvae, v;ere probably
frequently overlooked and their relative numbers are

103

probably much higher than the number of specimens in my col-
lection. O'Hara (1961) reports collecting members of this
family while Katz (1967) records the genera Bezzia and Culi-
coides from her collections. Since pupae cannot be keyed
and less than half of Florida's 22 genera are present in most
larval keys, I did not key out my ceratopogonid larvae and
pupae .

115. Unidentified ceratopogonid larvae and pupae--9
specimens in 8 collections at 4 locations in 2 counties.
Collections: 1, 15, 53, 70, 74, 76. 78, 89.
Maximum density: .031/plant at #89; 3.33/m2 at #78.
Water quality preference: hardness, r=.973, p=.005,
n=5; magnesium, 4=.994, p=.0005, n=5 ; sodium, r=.940, p=.018,
n=5; conductivity, r=.974, p=.005, n=4.

One ceratopogonid larva was collected in February while
the rest were found between May and August. The larvae came
from water high in sodium and magnesium and had high hardness
and conductivity.

Chaoboridae (Phantom Midges )

116. Corethrella prob . bradleyi (Coquillet) --5 speci-
mens in 3 collections from 3 locations in Alachua Co.

Collections: 24, 34, 89.

Maximum density: . 12/plant at #34.

These small mosquito- like larvae v;ere not common. Katz
(1967) reports them from one of her collections.

104

Chironomidae (Midg es) L a r v d e

Found in over half of my collections, chironomids ,
with 1,046 specimens, were my most abundant Diptera family,
comprising 82.7% of all Diptera collected , and only the
noterids as a family had more specimens. Of my 15 species
of chironomids, a single species, Chironomus attenuatus
Walker, accounted for 72.6% of my specimens. O'Hara (1961)
found chironomids to be ". . . by far the most abundant in-
sect larvae in the hyacinth community" (p. 43). His results may
be biased since he collected exclusively from canals in South
Florida. I found that chironomid larvae were especially
dense in canals such as Camps Canal. He did not go beyond
family level in his determinations. Katz (1967) also reports
chironomids as her most abundant insect family and lists 12
genera, of which only 3, Harnischia, Polypedilum-Phaenospectra
complex, and Tendipes (=Chironomus) , are represented among
the 12 genera I collected. Since she used the rather incom-
plete keys in Fennak (1953) , I believe some of her determina-
tions to be questionable. My specimens v.^ere all identified
by Mr. W. M. Beck, renowned chironomid specialist at Florida
A & M.

117. Ablabesmyia j anata (Roback)--lO specimens from
4 collections at Camps Canal in Alachua Co.
Collections: 74, 76, 82, 86.

Maximum density: .353/plant or 30/m at ,^82.
The larvae of this species were collected only in June
and August .

105

•'--'-^- AblabesTTiyia peleensis (WaLley)--8 specimens in
5 collections from 2 locations in Alachua Co.

Collections; 29, 31, 69, 74, 76.

2
Maximum density: 5 larvae/m at #69.

These larvae were collected between April and September.

Ablabesmyia sp . larva-~l specimen from a stream in
Charlotte Co.

Collection: 79.

Density: .009/plant or 5/m2.

This larva was too small to identify to species.

119. Chironomus attenuatus Walker larvae--760 specimens
in 25 collections at 8 locations in 4 counties.

Collections: 18, 22, 27, 34, 39, 41, 46, 49, 52, 54,
55, 71, 74, 76, 77, 79, 80, 81, 82, 84, 86, 89, 91, 92, 93.

o

Maximum density: 6.1/plant or 580/m'"' at #77.

Water quality preference: temperature, r=.570, p=.053,
n=12.

Insect associations: Belostoma sp. nymphs, r=-.661,
p=.053, n=9 ; Polycentropus sp. larvae, r=-.873, p=.054, n=5 ;
Pachydrus obniger larvae, r=.774, p=.021, n=0 .

This was my most abundant species of insect and it was
frequently very abundant, with an average density of 129.4
larvae per square meter, whenever it was collected. The maxi-
mum density of 580/m is almost twice tliat observed for any
other species. This single species comprised 72.6% of all
the chironomids collected and 13. 8X of all the insects found
and exceeded the number of specimens in the Coenagrionidae

106

or the Dytiscidae, two of my most abundant families. The
larvae live in tubes of silt and algae attached to the roots
and submerged portions of waterhyacinths .

120. Dicrotendipes leucoscelis (Townes) --single speci-
men collected at Camps Canal, Alachua Co., in October.

Collection: 35.
Density: .031/plant.

121. Dicrotendipes lobus Beck--single specimen collected
in July at Otter Creek, Levy Co.

Collection: 21.
Density: .077/plant.

122. Endochironomus nigricans Johannsen--2 specimens from
2 counties.

Collections: 71, 100.

Maximum density: .048/plant or 5/m- at #100.

123. Glyptotendipes lobiferus Say- -single specimen
collected in June at Camps Canal, Alachua Co.

Collection: 76.

Density: .009/plant or .588/m^.

124. Goeldichironomus holoprasinus (Goeldi)--18 speci-
mens in 6 collections at 4 locations in 4 counties.

Collections: 26, 33, 27, 43, 46, 78.
Maximum density: .39/plant at y/46 .

12 5. ii^iniiy^diia. sp.--2 specimens from 2 collections at
Camps Canal, Alachua Co.

Collections: 76, 82.

Maximum density: .059/plant or 5/m^ at #82.

107

126. Larsia sp.--6 specimens in 2 collections from
Camps Canal In Alachua Co.

Collections: 76, 80.

Maximum density: .043/plant or 2.94/m at #26.
These larvae were collected in late June and early-
August .

127. Parachironomus hirtalatus (Beck & Beck)--1 speci-
men collected in July at Otter Creek, Levy Co.

Collection: 21.
Density: .077/plant.

128. Parachironomus pectinatellae (Dendy & Sublette) --
1 specimen collected in November at Lake Talquin, Gadsden Co.

Collection: 96.
Density: .05/plant or S/m^.

Parachironomus sp . larvae--68 specimens in 4 collections
at 2 locations in 2 counties.

Collections: 74, 80, 81, 96.

2
Maximum density: .80/plant or 64/m at #80.

Of these larvae, which were too small to be identified

to species, 947, were from a single collection at Camps Canal.

129. Phaenospectra sp.--3 specimens in 3 collections
from 2 locations in 2 counties.

Collections: 31, 48, 53.

Maximum density: .030/plant at #53.

130. Polypedilum falla^c (Johannsen) - - 1 specimen col-
lected in November at Lake Talquin, Gadsden Co.

Collection: 96.

108

Density: .05/plant or 5/m .

131. Polypedilum illinoense (Malloch) -- 156 specimens
in 13 collections from 5 locations in 2 counties.

Collections: 29, 34, 37, 43, 50, 53, 54, 57, 74, 76,
80, 91, 96.

Maximum density: 1.56/plant or 125/m^ at #80.

Insect associations: Celina sp . larvae, r=.878, p=.021
n=6.

This was my second most abundant species of chironomid
and was my eighth most abundant overall. 125 larvae of this
species were collected in July at Camps Canal, where 88.5%
of the specimens were collected. Ivhile more were found in
the springtime, this species appeared irregularly throughout
the year.

Folypedilum sp. larvae- -2 larvae in 2 collections in
Alachua Co.

Collections: 40, 51.

Maximum density: .037 /plant at #50.

Culicidae (Mosquitoes) Larvae and Pupae

IJhile mosquitoes are about the only group of aquatic
insects whose presence beneath waterhyacinths has received
any attention, I did not find them particularly abundant,
with 19 collections having 82 specimens in 5 genera and 6
species. O'Hara (1961) did not report any from his collec-
tions in canals in South Florida. Barber and Hayne (1925)
reported 4 species of Anopheles found am.ong v/aterhyacinths

109

in the southern states. They found A. crucians Wiedemann
to be the most widely distributed and commonly collected
species but noted that A. quadrimaculatus Say, my most com-
mon anopheline, was the most common mosquito in some
waterhyacinth- infested lakes in Florida. My most common
mosquito larva, Coquillettidia perturbans (Walker), previ-
ously classified as part of the genus Mansonia, is considered
by Mulrennan (1962) and by Seabrook (1962) to be the most
common and im.portant mosquito species breeding in waterhya-
cinths in Florida. They also mention A. crucians and A.
quadrimaculatus . both species of Mansonia, and various Culex
species as being of lesser importance. Katz (1967) found 3
genera of mosquito larvae: Orthopodomyia , Mansonia (includ-
ing v/hat is now Coquellettidia perturbans) and Uranotaenia.
She collected no anophelines and amazingly her most commonly
collected species was Orthopodomyia signifera (Coquillett) ,
almost certainly a misidentif ication since this species is
almost strictly a tree-hole breeder, occasionally also being
found in artificial containers.

132. Anopheles crucians Wiedemann larvae- -1 larva
collected in August at Camps Canal, Alachua Co.
Collection: 86.

Density: .059/plant or 5/xa' at #86.

This vjas considered by Barber and Hayne (1925) to be
the most common waterhyaci nth-breeding mosquito in the
southern U.S.A. Both Mulrennan (1962) and Seabrook (1962)

110

consider this one of the more common species among Florida
waterhyacinths .

133. Anopheles quadrimaculatus Say- -21 specimens in 7
collections from 3 locations in 2 counties.

Collections: 3, 21, hi, 48, 50, 53, 89.

Maximum density: . 260/plant at #50.

The larvae of this malarial vector were fairly frequent
in situations where the waterhyacinth mat was not too dense
but they were never very abundant. Barber and Hayne (1925),
Hulrennan (1962) and Seabrook (1962) all consider this a com-
mon v.'aterhyacinth culicid.

134. Coquillettidia perturbans (Walker) --24 specimens
in 6 collections from 5 locations in Alachua Co.

Collections: 11, 12, 14, 16, 24, 34.
Maximum density: .214/plant at #16.

The larvae of this species, like other members of the
genus Man s on i a of which it was formerly considered a member,
attach themselves to submerged portions of aquatic plants by
their modified siphon and obtain their oxygen directly from
the plant. Since they readily drop off the plant when dis-
turbed, their frequencies beneath waterhyacinths are much
higher than indicated by the number of specimens in my collec-
tion. This species is probably the Mans on ia reported by
Katz (1967) and considered the most important waterhyacinth-
brecding mosquito species in Florida bv both Mulrennan (1962)
and Seabrook (1962). Tliis species was negatively correlated
with most diversity indices.

Ill

135. Culex territans Walker- -24 larvae and pupae col-
lected in July at a drainage ditch in Alachua Co.

Collection: 22.
Density: 1.33/plant.

A permanent pool species, the larvae are not usually
found in foul water such as waterhyacinths grow in.

136. Man s on i a titillans (Walker) --3 larvae collected
in September at a roadside canal in Indian River Co.

Collection: 6.

These were the only insects at this location, which had
a layer of oil on top of the water, probably washed in from
the adjacent Florida Turnpike.

137. Uranotaenia sapphirina (Osten Sacker)--9 speci-
mens in 4 collections from 4 locations in Alachua Co.

Collections: 34, 37, 86, 88.

2
Maximum density: . 167/plant at #37; 15/m at #85.

The larvae of this species prefer lakes and ponds with

floating or emergent vegetation and are "commonly associated

with Anopheles quadrimaculatus Say" (Carpenter and LaCasse

1955). However, only Katz (1967) mentions the genus as being

found among waterhyacinths .

Dixidae

138. Dixidae (?) pupa--a single pupa of what appears
to be a member of this family was collected in December at
the Peace River, Hardee Co.

Collection: 102.

2
Density: .063/plant or 5/m .

112

Dolichopodidae Pupa

139. Dolichopodidae (?) pupa--a single pupa of this
family was collected in November at a drainage ditch in
Alachua Co.

Collection: 40.
Density: .03/plant.

Fsychodidae Larva

140. Fsychodidae larva- -1 larva was collected in Janu-
ary at a drainage ditch in Alachua Co.

Collection: 51.
Density: .043/plant.

Stratiomyidae (Soldier Fly) Larvae

With 97 specimens, the stratiomyids comprised only 7 . 6%
of the Diptera (1.8% of total) but still were my second most
abundant dipteran family. This family v;as well-represented,
with 3 genera being found in 34 of my 88 collections. Fifteen
specimens of the genus Myxosargus , which comprised 817o of my
stratiomyids, key out as Euparyphus in Pennak (1953) and
Wirth and Stone (1968) . McFadden (1967) , whose key I used,
has not yet confirmed my identifications. O'Hara (1961)
found stratiomyid larvae occasionally abundant while Katz
(1967) recorded 3 genera, Odontomyia , Stratiomyia and Eupa-
ryphus .

141. Hodriodiscus sp. larvae-- 11 s[)ocimens in 6 collec-
tions from 2 locations in Alachua Co.

Collections: 39, 40, 43, 51, 76, 88.

113

Maximum density: . 123/plant at #88; 7.5/m^ at #75.
I'^Z. Myxosargus sp . I.arvae and pupae-- 79 specimens in
27 collections from 6 locations in Alachua Co.

Collections: 2, 11, 13, 24, 31, 33, 34, 35, 39, 41, 49,
50, 51, 52, 53, 54, 55, 56, 69, 70, 72, 81, 84, 86, 89, 92,
95.

Maximum density: .32/plant at #34; 30/m^ at #69.
Water quality preference: alkalinity, r=.872, p=.0O5,
n=8; hardness, r=.892, p=.003, n=8 ; nitrates, r=-.872, p=.002,
n=9.

Insect associations: Mesovelia sp. n}TTiphs , r = -.746,
p=.013, n=10; Desmopachria grana, r=.844, p=.034, n=6 ;
Pachydrus obniger larvae, r=.889, p=.018, n=6.

These larvae, which will key to Euparyphus in most keys,
were my third most abundant Diptera species and were repre-
sented in 30.77o of my collections. It was positively associ-
ated with Desmopachria grana beetles and with Pachydrus
obniger larvae. Highly significant correlations indicate
that this species prefers water high in hardness and low in
nitrates. It was collected throughout the year.

143. Stratiomyid sp. C-- 5 specimens in 5 collections
from 3 locations in Alachua Co.

Collections: 52, 53, 55, 83, 89.

o
Maximum density: .059/plant or 5/m^ at #83.

These larvae differed from my other stratiomyid larvae

in that they lacked the p>osterior plvmiose setae and the

paired hooks on the next- to-- las t ventral segment. All my

specimens were collected either in February or August.

114

Unidentified Strationiidae larvae--2 specimens from 2
collections at Lake Alice, Alachua Co.

Collections: 32, 35.

Stratiorayid larvae which were too poorly preserved
(after rearing attempts) to identify V7ere placed in this
group .

Syrphidae (Flower Flies) Larvae

144. Eristalis sp . larvae--9 specimens in 6 collections
from 3 locations in Alachua Co.

Collections: 13, 33, 35, 36, 91, 94.

Maximum density: . 10 /plant at #36; S/m^ at #94.

Rat- tailed maggots, as the larvae of this genus are
known, were collected only occasionally between July and
October. Katz (1967) also reports this genus from one of
her collections.

Tabanidae (Horse Flies) Larvae

Only 3 larvae belonging to 2 different genera were col-
lected of this family.

145. Chrysops sp. larva--l larva collected in June at
a culvert in Charlotte Co.

Collection: 79.

9

Density: .010 /plant or 5/m .

146. Tabanus sp. larvae- -2 specimens from 2 locations
in 2 counties .

Collections: 79, 83.

Maximum density: .059 /plant or 5/m^ at #83.

115

Tipulidae Larvae

147. Tipulidae larvae (unidentified) - -6 larvae in 5
collections from 4 locations in 2 counties.

Collections: 34, 37, 42, 43, 44.

These larvae were never common and x^7ere collected only
in October and December. Although several were reared to
adult stage, none have yet been identified. Katz (1967)
reports the genus Helius from 2 of her collections.

Diptera- -Unidentified

Unidentified Diptera pupae--5 specimens in 4 collections
from 3 locations in Alachua Co.

Collections: 49, 57, 72, 81.

These pupae, belonging to the suborder Cyclorrapha, could
not be identified. Since I was not sure even if they repre-
sented aquatic species, as opposed to having been washed in
from shore or overhanging vegetation, these forms were omitted
from my analyses.

116

per plant and per square meter are also ^iven. Similarities
or discrepancies with the lists of aquatic insects presented
by O'Hara (1961, 1968) and Katz (1967) are mentioned. Any
apparent seasonal or locality preferences are also noted.

Due to the length of the list, I will include here some
general observations on its content.

Mayfly nymphs and dobsonfly larvae v;ere uncommon, while
moth and caddisfly larvae were rare. Aquatic Hemiptera,
comprising 9.27c of the total specimens, were frequently col-
lected but usually were not particularly abundant at any site.
Of the Diptera, which comprised 23.1% of all specimens, only
the chironomid and stratiomyid larvae were frequently collected
v/ith the former sometimes being extremely abundant. Several
species of damselfly nymphs were frequent, with one species,
Ischnura posita , being the most frequently collected aquatic
insect species. Sixty- four species of beetles, comprising
45 . 57o of the specimens, were present, with the noterids and
several species of dytiscids being abundant and frequent.
Table 3 lists the 10 most abundant species (greatest number of
specimens) , while Table 4 presents the 10 most frequent species
(present in the greatest number of different collections) .

The species marked with asterisks obtain oxygen directly
from the water. Since waterhyacinth mats frequently have been
noted for the complete absence of dissolved oxygen (DO) beneath
them (Lynch et al. 1947, Ultsch 1971, 1973), few such forms
would be expected. Yet almost 33X of the specimens belonging
to the 10 most abundant species utilize DO. This indicates

117

Table 3. Ten most ahundanL insects collected from wa terliyaci nth roots
(from 88 collectinns, 1972-1974).

Rank

1,
2.
3,
4.
5.
6.
7.
8.
9.

10.

Sj)ecJ^es

:»Chironomus attenuattis Wali-rpr (Diptera :Ch1 ronomidae)
Suphigellus insularis (Sharp) (Col eoptera : Noteridae'
Supl-iisellus gibbulus ( A u b e ) ( C o 1 e o p t e r a : N o t e r i. d a e )

*Iscdm_ura posita (HaKen) (Odonata: Coenagri onidae)
Hydrovatus compressus Sharp (ColeopteraiDy ti.scidae)

^■Telebasis byersi WestfaJl (Odonata :Coenagrionidae)
ii!^iL!:£iiLS iiiy^tus (LeConte) (Coleoptera: Noteridae)

"Polypedilum illinoense (Malloch) (Diptera : Chironom. ^

^■Enallagma s^i_gjij^uin-£ollu_tam complex (Odonata:
Coenagri onidae)

''Miathyria marcella (Selys) (Odonata : Libellulidae)

%

N

Col.

Total

760

25

13.9

549

33

10.0

3 32

36

6.1

319

47

5.8

2 76

36

5.0

2 20

26

4.0

1 77

23

3.2

] 56

13

2.8

1 19

22

2.2

116

30

2.1

55.1

^Denotes dissolved oxygen-breathing form

Table 4. Ten most frequent insects collected from wa terbvacint h roots
(from 88 collections, 1972-1974).

Rank Species

1. '''Iscjrnura pqsj^ta (Hagen) (Odonata :Coenagrionidae)
2- Suphigellus gibbulus (Aube) (Coleoptera :Noteridae)

2. Hydrovatus compressus Sharp (Coleoptera : Oytiscj dae)
2. lixdji'Ciil'Jl^^llH-S. regius Young (Coleoptera : Noteridae)

5. Su2hJ;Se_^us ins_ul£ris (Sharp) (Col eoptera : Noteridae)

6. Pelocoris balius La Rivers (Hemiptera rNaucoridae)

7. '^^Pachj/dipjLax longipennis (Burmeister) (Odonata . -Li bellul . )

8. Pelocoris femoratu^ (Pallsot-Beauvois) (Hemiptera:

Naiicoridae)
Myxosargus sp. larvae (Dip tera : Strat iomyidae)
Hydrocanthus oblongus Sharp (Coleoptera :Nolerldae)

9.
10.

Col.

47

319

36

332

36

276

36

104

33

549

31

107

30

111

29

87

27

79

26

60

^Denotes dissolved oxygen-breathing form

118

that either the DO measurements are in error or that these
insects locate oxygen in some manner, perhaps from gas bubbles
on waterhyacinth roots.

Insect populations beneath waterhyacinLhs were generally
high. Only 7 collections contained less than 10 specimens,
whereas one beetle (Suphisellus insularis) was found at a
density of 'i'il /m.'^ of waterhyacinth mat and a chironomid

9

(Chironomus attenuatus) was found at a density of 580/m .

While certain species had significant correlations with
water chemistry parameters, no general water quality prefer-
ences xvere noted for larger taxonomic groups. Congeneric
species sometimes had completely different x-jater quality pref-
erences, perhaps indicating that these parameters act as
isolating mechanisms for these species.

Usually the biological significance of correlations be-
tween pairs of species was ambiguous since direct observa-
tions of interaction between the species would be necessary
to elucidate the reasons for the relationships.

Comparison of my species list with O'PIara's (1961) list,
which usually identified aquatic insects only to family level,
was noteworthy for O'Hara's omission of certain groups such as
noterids, which I found to be extremely frequent and abundant.
I believe that he misidentif ied Noteridae as Omophronidae .

Inspection of Katz 's (1967) list, where most insects were
identified to genera, revealed quite a few probable misidenti-
fications, probably due to her reliance on a single set of
identification keys (Pennak 1953) which omits many Florida genera,

119

Some species shov/ed definite seasonality in their abun-
dance. However, seasonal abundance seemed to vary with the
species and generalizations about higher taxon levels such
as families or orders do not appear to be valid. For instance^
one beetle species, Hydrovatus compressus , reached peak den-
sities during late winter while its congener, H. peninsularis ,
reached peak densities in late summer.

Physical and Chemical Variable Interrelationshi p_s

Correlation analyses were run on the physiometric plant
measurements and the chemical water quality data. All the
numeric data were "normalized" by taking the natural loga-
rithms of the values, this log transformation being common in
multivariate analyses of aquatic data (Green 1971, Stimac
and Leong 1977) .

The height of waterhyacinth plants v/as highly signifi-
cantly correlated (the p level for significance of the r
correlation statistic was .01 or less) with depth and water
temperature; had highly significant negative correlations with
chlorides, sulphate and sodium; and had significant (p level
less than .05) negative correlations with hardness, iron and
conductivity. Root length had a negative significant correla-
tion with depth, which was positively correlated with height.
Thus deeper waters were more likely to have taller waterhya-
cinths with shorter roots. This is directly opposite to
Coin's (1943) statement that root length varies directly with
water depth. The depth of the water had a highly significant

120

correlation with the number of specimens and species, a sig-
nificant correlation with magnesium, and significant negative
correlations with iron and potassium.

As can be seen from Table 5, which presents the correla-
tion matrix for the water quality data, almost all the water
chemistry parameters are interrelated. This makes analyses
of the relationships of these parameters very difficult, since
most multivariate statistical procedures assume that the in-
dependent variables are linear (orthogonal) in respect to each
other, i.e., the independent variables are assumed to be un-
correlated.

Regression Analyses

Stepwise multiple regression analyses of the data for
all collections did not reveal any variable or combination
of variables which were significant in their effects on the
numbers of species or specimens collected.

Comparison of Study Sit e s

Description

Three sites in Alachua County were sampled repetitively
during the duration of the study. The most intensively
studied area was Camps Canal, which drains a portion of Payne's
Prairie into Orange Lake. Located northeast of Micanopy on
State Road 234, about 10 meters wide, with steep sides quickly
dropping to a depth of 2+ meters, this site had a jam of water-
hyacinths at the SR 236 bridge. At the beginning of the

o

121

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122

growing season this jam consisted of a few patches of plants
in front of the bridge, but by early fall the jam stretched
over 100 meters upstream. A preliminary collection of aquatic
insects was made in August of 1972, with intensive sampling
begun in June of 1973. With the exception of late winter and
early spring when the waterhyacinths had almost disappeared,
another 28 collections were made at 2- to 3-week intervals
until the end of 1974.

Lake Alice, a shallow lake of about 33 hectares on the
University of Florida campus, was the second most intensively
sampled site, with 12 collections. A preliminary collection
was made in August of 1972, with the others made at odd inter-
vals throughout the latter part of 1973 and until August of
197A. Almost all my collections were made from the boardwalk
at the east end of the lake where depth vjas usually about 1-
l\ meters. Suitability for sampling varied with the season
and, more importantly, with the extent of the mechanical and
chemical waterhyacinth control measures being used at the time.

My third study site was a drainage ditch on the east
side of Interstate 75, 3.0 miles north of the Micanopy inter-
change. Consisting essentially of a small pond less than 10
meters wide surrounding a 2% meter deep hole, this site was
sampled 9 times beginning in July of 1973 when I first dis-
covered it. Unfortunately, the encroachment by the water-
penny, Hydrocotyle sp., was very rapid and by February 1974
there were few waterhyacinths left. When my last sample was
taken in August of 1974, there was only a tiny stand of pure

123

waterhyacinths remaining. Today the site is terrestrial
grasses and shrubs with a few cattails in the deep hole.

Species List Comparisons

Camps Canal was my most intensively studied site and
produced 2100 specimens of aquatic insects belonging to 96
species. Table 6 shows the 10 most abundant species and
Table 7 shows the 11 most frequently collected species.
Diptera larvae, especially chironomids , were exceptionally
abundant. Both species of naucorids were frequently col-
lected here. Ischnura posita was the most common damselfly
here, as it was at many collecting sites, but members of the
Enallagma signatum-pollutum complex were also common. By
common I mean both abundant and frequent. The noterid
Colpius inf latus was the most abundant beetle, and 3 other

embers of this family were frequently collected here. This
was the only site where hydrophilid beetles were frequent.
Caddisfly larvae as well as Megaloptera were collected almost
exclusively at Camps Canal.

Lake Alice (see Tables 8 and 9) , with 1283 specimens
and 55 species, had the greatest percentage of DO-breathing
insects of the 3 study sites. It v/as the only study site
at which mayfly nymphs made up more than VL of the insects
found there. Odonata nymphs were abundant and among the
damselfly species, I. posita nymphs were common, although not
as common as those of Telebasis byersi , which was uncommon
elsewhere. Beetles were the most common group, with Suphisellus

m

124

Table 6. Ten most abundant insects collected froni wn terhvacint h roots,
Camps Canal (from 29 collections, 1972-197^0.

Rflilk Species

10

!• "CALIo^LOFIILS attenuatus Walker (DipterarCIri ronomidae)
2- "Ischnura p_oj3ita (Hagen) (Odonota :Coenagrionidae)

3 . "To lyped 11 urn illinoense ( Ma 1 1 o c h ) ( I) i p t e r a : C 1 1 i r o n o ni . )

4. Colpius inf latus (LeConte) (Col eoptera : Noteridae)

5. Z_^o_c_oris ballus La Rivers (Hemiptera : Naucoridne)
^ • Suphisell us gibbulus ( Au h r ) ( C o 1 e o p t e r a : N t ) t e r l d a e )
^- Pelocoris femoratus (Pali sot-Beauvois) (Hemiptera:

Naucoridae)

8. "Enallagma signatum-pollutum complex (Odonata: 68 12 3.2

Coenagrionidae)

9. "Parachironomus sp. (Diptera:Chironomidae)
Hydrovatus peninsularls Young (Coleoptera :Dy tisc Ldae)

%

N

Col.

Totjsl

346

11

16.5

209

16

9.9

] 38

6

6.6

105

16

5 . 0

8/t

17

4.0

73

11

3.5

71

19

3.4

67

3

3.2

5 7

8

2.7
5 8 J)

^Denotes dissolved oxygen breathing forr

Table 7. Ten most frequent insects collected from wa terlivaci nth roots,
Camps Canal (from 29 collections, 1972-1974).

Rank Species Col^ J^

1. HvdrQ_eantlms regius Young (Coleoptera : Noteridae) 21 73

2- Pelocoris femoratus (Palisot-Beauvois) (Hemiptera: 19 71
Naucoridae)

3. Pelocoris balius La Rivers (Hemiptera :Naucoridae) 17 84

4. '^Ischnura posita (Hagen) (Odonata:Coenagr i onidae) 16 209
4. Colpius inflatus (LeConte) (Coleoptera:Noteridae) 16 105

6. Myxosargus sp. (Diptera: Stratiomyidae) 14 46

7. *Ejijy-la_gma slgruj_tum-p_ol^^^ complex (Odonata: 12 68

Coenagrionidae)

7. HjoijrocanJ^huj; oy.ojigiJs Sharp (Coleoptera : Noter idae) 12 23

9. *Chironomus attenuatus Walker (Diptera : Ch i ronomidae) 11 346

9. Suphisellus g^ibbulus (Aube) (Coleoptera : Noter idae) 11 52

9. Phaenotum exstriatus Say (Coleoptera :Hydrophi lldae) 11 20

'■Denotes dissolved oxygen breathing form

125

Table 8. Tpii most abundant insects collected from waterhyacinth roots,
Lake Alice (from 12 collections, 1972-1974).

Rank Species

■'■• Suphlsellus insularis (Sharp) (ColeopterarNoterldae)

2. Hydrovatus compressus Sharp (Coleoptera:Dytiscidae)

3. *Telebasis byersi Westfall (Odonnta: Coenagrionidae)
^- '^-Chironomus aj^tenuatus Walker (Dip tera: Chironomidae)
5. Mesonoterus add end us (Blatclnley) (Coleoptera:

Noteridae)
^- *lschnura posita (Ilagen) (Odonata :Coenagrionidae)
7. '''Pachydlplax longipennis (Burmeister) (Odonata:

Libel lulidae)
^- Suphlsellus sp. larvae (Coleoptera :Noteridae)
9. ^Callibaetis f loridanus Banks (Ephemeroptera : Baetidae)
10. Myxosargus sp. larvae (Diptera: Stratiomyidae)

%

N

Col.

Total

420

12

32.7

175

11

13.6

169

3

13.2

111

9

8.6

62

10

4.8

39

9

3.0

25

4

1.9

23

4

1.8

18

3

1.4

15

7

1.2

82.2

*Denotes dissolved oxygen breathing form

Table 9. Ten most frequent insects collected from v.'n terhyacin th roots.
Lake Alice (from 12 collections, 1972-1974).

Rank S])ecies Col.

-'-• Suplrisellus insularis (Sharp) (Coleoptera :NoterIdae)

1. '-'^lelebasis byersi Westfall (Odonata: Coenagrionidae)
3 . Hydrovatus compressus Sharp ( C ( "> 1 c o p t e r a : D y t i s c j d a (.^
^' Mesonoterus add end us (Blatchley) (Coleoptera :Noteridae)

5. "Ischnura p_osi_ta (Hagen) (Odonata :Coenagrionidae)
-' ' Hydrocanthus regius Young (Coleoptera :Noteridae)
7. Myxosargus sp. (Diptera : Stra ti omyi dae)
7. T_c'_itH;or^.Ls baliu^ La Rivers (Hemipt era :Naucor idne)

9. *Chironomus attenuatus Walker (D ip tera : Chironomidae)
10. Celina sp. larvae (Coleoptera :I)ytiscidae)

12

420

12

169

11

175

10

62

9

39

9

14

7

15

7

9

6

111

5

10

*Denotes dissolved oxygen hreattiing. fi

126

insularis the most common insect at this site. Almost 90%

of all the specimens of another noterid, Mesunoterus addenclus ,

were collected here.

A total of 661 specimens belonging to UG species was
collected at the 1-75 drainage ditch site. Table 10 presents
the 10 most abundant species and Table 11 shows the 10 most
frequently collected species at this site. Probably the most
noteworthy point is the frequency and abundance of the Helodi-
dae beetle larvae belonging to the genus Ora. This genus was
not found at any other site. The larvae of Sc_irt_es, another
helodid, were also common here but uncommon everyvjhere else.
The relatively high abundance of Culex tx^rritans , a genus of
mosquito which was not collected elsewhere, is probably due
to the hatching of a single egg raft. The noterid beetle,
Suphisellus puncticollis , was also relatively abundant here,
with almost half of the 44 specimens of this species being
collected at this site. This site had relatively fewer DO-
breathing forms (noted with an asterisk), perhaps indicating
a greater tendency towards anaerobic conditions.

The use of discriminant analysis demonstrated that the
different abundances of these various species of insects were
not due to chance. By performing a liotelling T"^ test on the
generalized squared distance to the group, an F-value for
testing the significance of difference between any 2 groups
could be evaluated (Morrison 1967) . In this manner it was
found that the abundances of the insect species at Camps Canal
were highly significantly different from those at both Lake
Alice and the drainage ditch. Lake Alice was significantly

127

Table 10. Ten most abundant insects coJlectcd from wnterlivac i ntli roots,
1-75 drainage ditch (from 9 collections, J 972-1 974).

Rank I'PA'^jes

Suphlsellijs gibbulus (Aube) (Coleopt era: Noteridae)
C^ra spp. larvae (Coleoptera rllelodidae)
*lschnura poslta (Hagen) ((Hlonata: Coenagr ionidae)
Belostoma sp. nymphs (Hem i ptera :Belos toma tidae)
Scirtes sp. larvae (Coleoptera rHelodidae)
Culex territans Walker (D,i pt erarCulic idae)
Suphisellus puncticollis Crotch (Coleoptera rNoteridae)
Colpius inf latus (LeConte) (ColeopterarNoteridae)
Hydrovatus peninsularis Young (Coleoptera : Dytisr idae)
Belostoma testaceum (Leidy) (llemipterarBelostomat idae)

%

N_

Col.

Total

233

7

35.2

92

8

13.9

39

6

5.9

34

4

5.1

25

5

3.8

24

1

3.6

2 1

5

3.2

20

3

3.0

16

5

2.4

]5

6

2.3

''"Denotes dissolved oxygen breathing form

Table 11. Ten most frequent Insects collected from wa ter hvac i n th roots,
1-75 drainage ditch (from 9 collections, 1972-1974).

Rank Species

1. Ora spp. larvae (Coleoptera :Helod idae)

2. Suphisellus gibbulus (Aube) (Coleopte ra :Noteridae)

3. >'clschnura posita (Hagen) (Odonata:Coenagrionidae)
3. -ATelebasis byersi Westfall (Odonata rCoenagrlonidae)

3. Belostoma testaceum (Leidy) (Hemlptera rBelostomatidae)

6. Scirtes sp. larvae (Coleoptera:Helodidae)

6. Suphisellus puncticollis Crotch (Coleoptera :Noteridae)

5. Hydrovatus peninsularis Young (Col eoptera :Dytiscidae)

9. Belostoma sp . nymphs (Hemiptera:Belos tomatldae)

10. "'I'illXEfL^iliEl illinoense (Malloch) (Diptera rChironomidae)

Col.

N

8

92

7

233

6

39

6

13

6

11

5

25

5

21

5

16

4

34

4

4

'Denotes dissolved oxygen breathing form

128

different (and just shy of being highly significantly differ-
ent) from the drainage ditch. These comparisons were based
on the abundances of only the 10 most frequent species overall
(see Table 3). As the last part of the discriminant analysis,
the SAS program classifies each collection as to which site
it should have come from based on the abundances of these 10
species. Only 3 collections (2 from the drainage ditch, 1
from Lake Alice) out of the 50 were classified incorrectly.
This technique with its ability to discriminate between 3
similar, eutrophic, waterhyacinth-f illed , aquatic sites, based
just on the abundances of 10 species of insects, could have a
very real practical value for those engaged in monitoring and
classifying aquatic ecosystems. Only a relatively few fre-
quently-encountered species would have to be identified in
order to compare an aquatic ecosystem witli others or with pre-
vious collections from the same site. The need for locating
certain bioindicators of water quality or the measurement of
dynamic, rapidly fluctuating water chemistries would be elim-
inated.

Estimation of Total Number of Spe c i e s

Plots of the cumulative number of species versus the
cumulative number of specimens were made for each of the study
sites. After obtaining estimates of b and of S--, the estimated
number of species in the study area, through the procedure
discussed in the methods section, an exponential curve was
fitted to the data using SAS PROG NLIN. The Marquardt method,

129

a least-squares approach, was used for the fitting of the
curve, although the other optional methods gave virtually
identical curves. The F-value for the goodness of fit was
over 150, extremely significant, for all 3 curves fitted in
this manner.

As can be seen from Fig. 3, the species accumulation
curve for Camps Canal becomes asymptotic at a value of 90.2
species. The standard error for the estimated asymptote is
1.78, V7ith the 957o confidence interval being S- + 2 standard
error. Since 96 species were actually found at Camps Canal,
this gives a sampling efficiency of 106.57.. Several factors
help explain why the predicted number of species is lower
than the actual number of species found. The least squares
approach and most other statistical methods of curve fitting
will usually, if the variation in the data is similar, result
in a line where approximately an equal number of points are
above and below the curve. In this case some of the points
above the curve are near the end where the curve becomes
asymptotic. This statistical approach to fitting a curve
makes no assumptions as to the distribution of specimens among
species or minimum level for the asymptote.

Another factor leading to a low estimate of total species
is the abrupt addition of seasonal and possibly even succes-
sional forms. As can be seen from Fig. 3, the number of species
begins to increase in the beginning of May (point A), starts to
level off by late June (point B) , and stays at a steady level
of species until the end of August (point C) . The new species,

130

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133

mostly HemipLera, appearing in May are not necessarily in-
creasing the number of species actually present since some
probably replace species, such as emerging damselflies, no
longer present at the sampling site. If many collections
(say 25) were made per season, the resultant species accumu-
lation curve would probably show a series of steps of de-
creasing size, marking seasonal turnover of species for the
first few years. For a relatively short term of study like
this (essentially 1% years), the asymptote predicted is
heavily influenced by last series of collections which show
no new species, i.e. the last seasonal asymptote reached.
Thus, since my study ended shortly after the winter level of
species was reached, the predicted asymptote was therefore
influenced by the lower value reached during the preceding
sumiiier.

This seasonal factor is also present in the estimation
for the total nmTiber of specimens at Lake Alice. As can be
seen from Fig. 4, the predicted number of total species is
46.2, while 55 species, 119X of the predicted value, were
actually collected. Again, it appears that the period from
Nov. 19 (point A) through Feb. 9 (point B) , with its slow
rate of acquisition of new species, influenced the predicted
curve downward. There were not enough collections after
June (point C) to establish the existence of a new asymptote
(probably close to a value of 55) and to increase the predicted
value of S". It should also be noted the actual value of 55
species lies on the upper boundary of the 95% confidence

134

interval limit for the mean (standard error = 3.91). Thus
the underestimation may be due in part to the variation in
the data.

There is too little data for the drainage ditch site to
demonstrate seasonal changes in the number of species (see
Fig. 5). For this study site the predicted total number of
species, S-', is 51.5 (standard error = 2.53) and 46 species
were actually collected, giving a sampling efficiency of
89.3%.

The species accumulation curve method appears to be a
potentially useful tool in community ecology. A fairly good
estimate of the total number of species in a sample site could
be obtained if several years' worth of collections were used in
order to minimize seasonal influences. A good estimate of the
seasonal level of species could be obtained by intense sampling
confined primarily to a single season. The plotting of a
species accumulation curve is also a good method for demon-
strating the size and timing of seasonal turnover of species.

Another way of estimating S-'' is to assume (or demon-
strate) that the species are distributed in some set manner.
In 1948 Preston proposed the lognormal distribution of species.
The lognormal distribution pattern assumes that the specimens
per species are distributed in a geometric or logarithmic
series v.^hile tlie abundance of species has a normal distribu-
tion. Preston (1948, 1958, 1962) found tbat this lognormal
distribution is very satisfactory in explaining the distribu-
tion of species abundances of a large variety of organisms,
especially of insects. May, in his elegant review (1975) of

135

distribution patterns and their effects on diversity, states
that "For large or heterogeneous assemblies of species, a
lognormal pattern of relative abundance niav be expected" (p.
106). Thus, the assumption that my abundances of aquatic in-
sect species are lognormally distributed seems to be well-
founded. Actual, conclusive demonstration that this distri-
bution pattern is the correct one is difficult since, as
Price (1975) points out , ". . .a line can be fitted to any
distribution data, and it does not mean that it is a good
model, nor that the explanation for the fit is necessarily
the only explanation" (p. 365). The logn-irmal distribution
has intuitive appeal, its applicability to insects has been
demonstrated, and this pattern allows the computation of S",
the total number of species.

Its m.ain drawback, as mentioned in the methods section,
is fitting a truncated normal curve to the data. Since I did
not, at this time, have the necessary resources to do so sta-
tistically, I therefore fitted a curve to my data points visu-
ally. Fig. 6 shows a species abundance curve for the Camps
Canal study site. By visual inspection, s , the number of
species in the modal octave R^ , is approximately 16. Assum-
ing a=0 . 2 (as shoiNm by Preston 1948) and solving S- = s /iT/a,
S'''=141.8 species. This is quite a bit higher than the 90.2
species estimated by the species accumulation method or the
actual 96 species collected. Sampling efficiency v;ould be 67.7%

The species abundance curve for Lake Alice is shown in
Fig. 7. The num.ber of species in the modal octave is approxi-

136

Number of specimens per species

Figure 6. Species abundance curve for Camps Canal, visually
fitted.

(~> c t a v G

Number of specimens per species

')!

Figure 7. Species abundance curve for Lake Alice, visually
fitted.

137

10

K)

O
U

m
S

1 ;' i •'; S f> / ;; ocl. nvf

2 /i 8 ic r' r,,'', ];'!; ■>',(,

Number of specimens per species

Figure 8. Species abundance curve for 1-75 drainage
ditch, visually fitted.

138

niately 9, resuJ. Ling in a value of 79.8 species for the esti-
mate of S*. This also is much higher than the 52 species
estimated by the previous method or the 5 3 species actually
collected. The calculated sampling efficiency now drops to
68.97o.

The species abundance for the 1-75 drainage ditch is
shown in Fig. 8. The number of species in the modal octave
is approximately 8, which results in an estimated 70.9 species
This again is much more than the previously estimated S" of
5]. .5 species or the 46 species actually collected. Sampling
efficiency for this site then becomes 64.97o.

While previously the estimated sampling efficiency was
nearly 100% for all 3 sites, this figure drops down to under
707o using this crude approximation of Preston's lognormal
curve method. If the actual value of a had been 0.227 (a
value observed by Preston, 1948), then sampling efficiency
would have increased to around 75%. Thus the high estima-
tion of total species present at the sites may be partly due
to assuming a low value of a. Another reason why species
abundance mettiod yields such high estimates of S-'' may be be-
cause a static relation between abundances of the various
species is implicitly assumed. Thus, in estimates based on
short-term collecting, seasonal and other variations affect-
ing the relative proportioTis of species are magnified, result-
ing in a higher S"--. Also, no doubt, there are probably some
extra species in the collections v;hich could not be deter-
mined because they v;ere larval forms or pupae. However, these

139

few species would have a. minimal effect. A long-term study
of many years, like most of the data analyzed by Preston,
would smooth out seasonal variations and add new species and
help confirm or refute the validity of this method.

Both the species abundance curve metliod and especially
the species accumulation curve method could be employed to
answer some interesting general ecological questions concern-
ing species-area relationships as well as problems about the
aquatic insect community of x-zaterhyacinths . By collecting
aquatic insects fairly intensively at 10 or more v/aterhya-
cinth communities in Florida whose area of infestation is
kno\^7n , an estimate of the number of species at each site could
be made. Plotting the number of species versus the log of the
area would allow comparison with MacArthur and Wilson's (1967)
predicted relationship between the number of species and the
size of islands.

If this procedure were then repeated in Argentina, the
probable point of origin for waterhyacinths , and the slopes
of the lines compared, evidence would be provided of whether
the aquatic entomofauna of waterhyacinths has reached species
saturation, since the introduction of wa terhyacinth approxi-
mately 90 years ago. Saturation would be indicated if the
number of species of aquatic insects in v/aterhyacinth communi-
ties in Florida was approximately the same as the number of
species in Argentinian waterhyacinth communities of the same
size. Strong (1974a) has indicated that tree insects in
Britain reach saturation levels of species on trees within

140

300 years of their introduction of a new tree species. He
(1974b) also has shovm that the insect pests of cacao probably
saturate within 72 years of the introduction of this plant to
a nexv' geographical area. Thus saturation of the number of
aquatic insect species beneath v;aterhyacinths could have
occurred in less than 100 years.

Factors Affecting the Number of Species and Genera

I\^ile stepwise multiple regression analyses of the data
from all 88 collections revealed no significant variable or
combination of variables which affected the number of species
or specimens found, when the sites were considered separately
this was no longer the case. Stepwise multiple regression
analysis differs from simple multiple regression analysis in
that each variable being considered is entered one at a time
and its contribution to explaining the variation is then
tested. Simple multiple regression forms a model consisting
of all the variables being considered and then tests for sig-
nificance. Since many variables do not liave a significant
effect, their addition to the model just adds "noise" and

reduces the amount and significance of the variation explained.

2
The maximum R improvement method of stepv;Lse regression,

the method I used, calculates the amount of variation ex-

0

plained, R'- , tor all possible models having that many vari-
ables before adding another variable to the model (see Barr
et al. 1976) .

Using this method, a liighly significant model for the
number of species found at Camps Canal v/as :

141

species = 14.229 + 16.448(iron) - .323(root length).

This model of the dependence of the number of species on the
level of iron in the water and shorter root length explained
58.21 of the variation and was significant at p=.0083 level.
The number of genera present at Camps Canal was significantly
dependent only on the level of iron:

genera = 12.307 + 13 . 538 (iron) .

At Lake Alice the number of species present was dependent
at a highly significant level (p=.0016) on the height and root
length of the waterhyacinths :

species = 15.873 - .133(height) + .216(root length).

The number of genera at Lake Alice was similarly explained:

genera = 17.083 - .136 (height) + .158 (root length).

No significant combination of variables was found to explain
the number of species and genera at the drainage ditch site.

Diversity Studies

General

If one assumes that the distribution of individuals
among species, i.e., the relative abundances of species, is
significant, it would be of interest to determine what
factors influence it. As I have demonstrated in the previous
section that the differences in the numbers of individuals

142

among different species at different sites were highly sig-
nificant, a single statistic which expresses that relation-
ship between number of individuals and number of species
would be of great value in determining what factors influence
this difference between distributions. An obvious choice is
the use of a species diversity index, especially one that in-
cludes components for both richness and equitablility . Such
indices are commonly used to determine the effects of various
factors on the species composition of a community. Wilhm and
Dorris (1968, Uilhm 1972) liave demonstrated the use of Shan-
non's diversity index for stream insects in determining stream
pollution, while Allan (1975) has used diversity of aquatic
insects as a means of detecting the effects of altitude and
substrate size.

Because the controversy about the choice and applicabil-
ity of the various diversity indices m.ade an a priori selection
of a single index difficult, I used Shannon-Weaver's H', Simp-
son's D, and the rarefaction index E(S^). The rarefaction in-
dex was calculated at two levels, n=10 and n=25 . As a check
and for comparison purposes, the number of specimens per
species, SPCMII/SPP, was also used. Table 12 presents the aver-
age values for these diversity indices at my 3 study sites and
for all 88 collections. Duncan's multiple range test revealed
no significant differences betv\'een the means of any single in-
dex at the 3 studv sites.

Dependence on Sample Size

In order to facilitate comparison between different col-
lections, a diversity index should be independent of the

143

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numbei- of specimens. However, inspection of the correla-
tions between the indices I used and the number of specimens
revealed that this was not always the case. Shannon's in-
dex had a significant correlation and specimens per species
were highly significantly correlated ivith the log-transformed
values of the number of specimens, while the 2 rarefaction
indices both had high negative correlations. When the un-
transformed values for the number of specimens was used, the
significances of the correlations were the same except for
Shannon's index, which no longer showed a significant relation
to the number of specimens. Only Simpson's index consistently
showed no correlation to sample size.

Relations to Plant Part Size, Depth, and Time of Year

Stepwise multiple regression of the waterhyacinth morpho-
metric measurements (root length, height, root-shoot ratio),
time of year and depth, on the various diversity indices re-
vealed no significant relationships v/hen the data from all 88
collections were used. However, when the data for each study site
were considered separately, several significant and highly
significant relations were discovered. This would indicate
that the effects of any variable upon a diversity index are
not constant but vary from location to location. Thus the
length of waterhyacinth roots had a significant negative
effect on Shannon's index at Camps Canal but a highly signifi-
cant positive effect on this same index at Lake Alice. No
significant relation to Shannon's index with any combination
of the 5 variables being tested was found for the 1-75 ditch

145

study site. However, at this site, depth had a significant
effect on Simpson's index, which showed no significant rela-
tionships to any of these variables at the other 2 sites.
The rarefaction indices were found to be negatively related
at a highly significant level with depth of water at Camps
Canal, positively related at a highly significant level with
root length at Lake Alice, while no significant relationships
were revealed at the 1-75 ditch study site. The number of
specimens per species was not significantly related to any
combination of the 5 variables at Lake Alice. At Camps Canal
a 2-variable model, positive root length and depth, showed a
highly significant effect in explaining the variation in
specimens per species, while at the 1-75 ditch this variation
was explained at a highly significant level by a model influ-
enced positively bv root length and negatively by height.

It should be noted that even highly correlated variables
such as depth and root length were used in these analyses.
Stepwise regression analysis, in effect, compensates for cor-
related variables. If a variable is entered into the model,
the variation explained by that variable is similar to that
explained by the variables correlated with it. Thus a cor-
related variable would explain little additional variation
and is usually not entered into the model until much later
steps. For (.his reason, the statisticians at the University
of Florida advise me that the use of all variables, including
correlated ones, is justified in stepv;ise regression analysis
(Dr. Ramon Lit tell, Ilr . I^alter Of fen , personal communications.)

146

Relationships to Water Quality Parameters

Stepwise multiple regression analvsis was also used to
ascertain possible relations of water quality parameters to
the various diversity indices. All 13 water quality param-
eters were included in the analyses. The 5 plant and site
variables previously analyzed and the number of petioles per
plant and the number of plants per meter were also included
in the analyses. In this manner not only would the indirect
effect of plant-water quality interactions be taken into ac-
count, but the relative importance of any variable could be
judged by when it appeared in the model.

As in the previous stepv/ise regression analyses, a model
was considered significant if the amount of variation ex-
plained was significant, i.e. the p-level for r was less
than .05, and if the coefficients for all the parameters in-
cluded in the model were also significant. The model chosen
as the "best" model was one which had the lowest p-level for
r" and still had significant coefficients for all the param-
eters included in the model.

VJater quality data were available only for 34 of my collec-
tions. Camps Canal had 12 collections with these data , while
Lake Alice and the 1-75 ditch did not have enough to be ana-
lyzed separately.

Klien all 34 collections having water quality data were
analyzed, the results were not particularly enlightening.
Either no significant model was found or a great number of
parameters were included in the "best" model, making

1A7

interpretation difficult. As noted in the previous analysis,
a variable does not necessarily have the same effect on
diversity at different locations. I^Jhen Camps Canal was con-
sidered separately, fewer variables were required to provide
the "best" model. Table 13 lists the 4 most important param-
eters affecting diversity at Camps Canal and overall. In-
spection of the list provides some interesting generaliza-
tions. Most noteworthy was the importance of alkalinity (or
one of the variables, such as pH or hardness, highly corre-
lated with alkalinity) in its effects on diversity indices.
Higher diversity was associated with loxi/ levels of alkalinity
or one of its correlated parameters. Higher diversity was
associated with high levels of iron, at least at Camps Canal.
Root length and plant height were less important than water
quality parameters, not appearing anj^where on the list.

Conclusions- -Choice of Indices

All of the diversity indices showed extremely high
correlations (p=.0001 or less) with one another, yet they
did not respond the same way. The rarefaction diversity
indices V7ere most sensitive to environmental parameters but,
unfortunately, also to sample size.

None of the indices was adequate in distinguishing
between the three study sites. Since discriminant analysis
could distinguish these sites on the basis of just the abun-
dance of 10 species, this would indicate that the information
lost by combining the species distributions into one statis-
tic negates its usefulness as an analytical tool.

14

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149

Van Emden and VJilliains (1974) , Pielou (1969) and others
have questioned the wisdom of combining species richness and
species equitability into one statistic. Thus, species rich-
ness may be decreasing, but because the rare species are
disappearing, species evenness may be rising, resulting in
no change in the value of the index. A separate calculation
for richness component would be recommended, especially with
the use of a richness index such as the rarefaction index.
However, most of the existing measures of evenness have been
criticized, with especially concise arguments being offered
by Sheldon (1969), DeBendictis (1973) and Peet (1974, 1975).
Edden (1971) offers an intuitively appealing measure of even-
ness based on the lognormal distribution. However, the dif-
ficulty of fitting a lognormal curve has already been discussed.

Stout and Vandermeer (1975) , who calculated the total
number of species expected at a site using species-area rela-
tionships, state "Vie can see no justification for computation
of H or equitableness or evenness in spite of the current
popularity of such computations in the ecological literature"
(p. 269). I basically agree with them. Calculating the
estimated total number of species at the collecting site
would be the recommended approach. However, if some type of
diversity index is necessary, such as for comparing single
collections for v;hich total number of species cannot be cal-
culated, I would choose the rarefaction index primarily be-
cause of its ease of interpretation and intuitive appeal.

SUMIARY

A total of 5485 aquatic insects were collected from
37 different tnonotypic waterhyacinth communities in 18 Flor-
ida counties. At least 147 species of insects were identi-
fied and the identifications confirmed by experts. Aquatic
insects were numerous at most sites and although the low
level of dissolved oxygen (DO) beneath waterhyacinth mats
has often been noted, DO-breathing forms were frequent and
abundant. The most abundant families of insects were midge
larvae (Chironomidae) and the burrowing v/ater beetles (Noter-
idae) .

The abundances of individuals in each species has
biological significance since discriminant analysis dis-
tinguished the 3 repetitively sampled study sites from each
other based on the abundances of the 10 most frequent in-
sect species.

The estimated total number of species at each of the
3 study sites v;as approximately equal to or less than the
total number of species actually collected when the species
accumulation curve method xv-as used for the estimates. Using
Preston's (1948) lognormal distribution method of construct-
ing a species abundance curve to estim.ate the total number
of species resulted in estimates which indicated that approx-
im.ately 707.^ of the available species actually had been col-
lected.

150

15:

Three different diversity indices were calculated with
the hope that reduction of relative species abundances to a
single statistic would help in determining the effects of
various environmental parameters on these abundances. All
3 indices indicated a relation betv/een increased diversity
and lower values of alkalinity and the parameters strongly
correlated with it. Higher levels of iron increased diver-
sity, at least at the Camps Canal site. Hov/ever , these in-
dices were incapable of distinguishing the 3 study sites,
indicating a loss of information in combining species abun-
dance information into a single statistic. The utility of
diversity indices appears to be limited. If the total num-
ber of species in the sample area cannot be estimated, the
use of a diversity index to compare collections may be jus-
tified. In such a case I would recommend the rarefaction
diversity index E(Sj^) because of its intuitive appeal, ease
of interpretation and sensitivity to effects of environmental
parameters .

REFERENCED CITED

Agostini, G. 1974. El genero Eichhornia (Pontederiaceae)
in Venezuela. Acta Bot . VenezueTTca 9 (1 =4) : 303-310 .

Allan, J. David. 1975. The dis Lributional ecology and

diversity of benthic insects in Cement Creek ,'' Colorado
Ecology 56:1040-1053.

Andres, L. A., and F. D. Bennett. 1975. Biological control
of aquatic weeds. Annu . Rev. Entomol. 20:31-45.

Anonymous. 1896. Clogged by hyacinths - Navigation on the
St. Johns, Florida, seriously obstructed. The Sun
[newspaper], New York, Sept. 20, 1896.

Anonymous. 1966. Composite list of weeds. Weeds 14(4)-
347-386.

Barber, M. A., and T. R. Hayne. 1925. l/ater hvacinth and
the breeding of Anopheles. U. S. Public Health Serv
Rep. 40(47) : 2557-2562.

Barr, A. J., J. H. Goodnight, J. P. Sail and J. T. Helwig.

1976. A user's guide to SAS 76. SAS Institute, Raleigh
N. C. 329 pp.

Bennett, F. D. 1967. Notes on the possibility of biological
control of the water hyacinth Eichhornia crassipes.
PANS 13(40:304-309. —

Bennett, F. D. 1968a. Insects and mites as potential con-
trolling agents of water hyacinth (Eichhornia crassipes
(Mart.) Solms.). Proc. 9th Brit. Wee^^ontrol ConFT
832-835.

Bennett, F. D. 1968b. Investigations on insects attacking
water hyacinths in Florida, British Honduras and
Jamaica. C.I. B.C. Report (unpublished). 9 pp.

Bennett, F. D. 1970. Insects attacking water hyacinth in
the West Indies, British Honduras and the U.S.A. Hya-
cinth Control J. 8(2): 10-14.

Bennett, F. D. 1972. Survey and assessment of the natural
enemies of water hyacinth, Eichhornia crassipes. PANS
18(3) :310-311. ^

15;

153

Bennett, F. D. 1974. Biolof;;ical control. Pages 99-106 in
D. S. Mitchell, ed. Aquatic vegetation and its use arid
control. UNESCO, Paris.

Bennett, F. D., and H . Zwolfer. 1968. Exploration for natur-
al enemies of the water hyacinth in northern South Amer-
ica and Trinidad. Hyacinth Control ,J . 7:44-52.

Berner, Lewis. 1950. The mayflies of Florida. Univ. of
Florida Press, Gainesville, Fla. 267 pp.

Berner, Lewi.s . 1968. Ephemeroptera . Pages Hl-ri9 in Frank

K. Parrish, ed. Keys to water quality indicative organ-
isms (Southeastern United States) . Federal Hater Pollu-
tion Control Admin. U. S. Dept. Agri .

Blackburn, R. D. 1974. Chemical control. Pages 85-98 in

D. S. Mitchell, ed. Aquatic vegetation and its use~and
control. UNESCO, Paris.

Blatchley, W. S. 1914. Notes on the winter and early spring
Coleoptera of Florida, with descriptions of new species.
Canad. Entomologist 45:61-66, 88-92, 140-144, 247-251.

Blatchley, W. S. 1925. Notes on the dis tril^ution and habits
of some Florida Coleoptera, v;ith descriptions of new
species. Canad. Entomologist 57:160-168.

Blatchley, W. S. 1932. In days agone : Notes on the fauna

and flora of subtropical Florida in the days when most

of its area was primeval wilderness. Nature Publ. Co.,
Indianapolis. 338 pp., 14 pis.

Bock, J. H. 1966. An ecological study of Eichhornia eras-
si pes_ with special emphasis on its reprocTucEive^biology .
Ph.D. dissertation in botany, Univ. of California.
175 pp.

Boyd, C. E. , and E. Scarsbrook. 1975. Influence of nutrient
additions and initial density of plants on production
of vjaterhyacinth, Eichhornia crassipes. Aquatic Bot.
1(3):253-261. '

Brillouin, L. 1960. Science and information theory. 2nd
ed. Academic Press, New York. 320 pp.

Buckman , H. H. 1930. A report on an investigation of the

water hyacinth for the City Commission of Jacksonville,
Florida. Buckman and Co., Engineers, Jacksonville, Fla.
41 pp.

Bullock, J. A. 1971. The investigation of samples contain-
ing many species. I. Sample description. Biol. J.
Linn. Soc. 3:1-21.

15A

Burkhnlter, Alva P. 19 7<^i. Aquatic weed identification and
control manual. Bureau of Aquatic Plant Research and
Control. Florida Dept. Natural Resources. 100 pp.

Byers. C. Francis. 1930. A contribution to the knowledge

of Florida Odonata. Univ. of Florida Press, Biological
Science Series, 1(1):3.?7 pp.

Carpenter, Stanley J., and Walter J. LaCasse. 1955. Mosqui-
toes of North America (north of Mexico) . Univ. of
California Press, Berkeley. 360 pp., 127 pis.

Cason, James H. 1970. Lake Alice--A studv of potential pol-
lution of Florida aquifer. The Compass 47 (4) : 206-210 .

Center, Ted. D. 1976. Pot;ential of Arzama dens a (Leipdoptera
Noctuidae) for the control of watcrKyacinth with special
reference to the ecology of waterhyacinth (Eichhornia
crassipes (Mart.) Solms) . Ph.D. dissertation, Univ. of
Florida, Gainesville. 334 pp.

Center, Ted D., and J. K. Balciunas. 1975. The effects of
water quality on the distribution of alligator weed and
v/ater hyacinth. Integrated program for alligator weed
management. U. S. Army Engineer, Waterways Experiment
Sta., Vicksburg, Miss." Tech. Report No. 10:B1-B13.

Chadwick, J. J., and M. Obeid. 1966. A comparative study of
the growth of Eichhornia crassipes ami Pistia stratiotes
in water culture. J. Ecol.' 54:563-575.

Chandler, Harry P. 1956. Mcgaloptera. Pages 229-233 in
R. L. Usinger, ed. Aquatic insects of California.
Univ. of California Press, Berkeley.

Chapman, H. C. 1958. Notes on the identity, habitat and

distribution of some semi-aquatic Hemiptera of Florida.
Fla. Entomol. 41 (3) : 117- 124 .

Charudattan, P. 1975. Use of plant pathogens for control of
aquatic weeds. Ecol. Res. Serv. , U. S. E.P.A. 660-3-75-
001:127-153.

Cody, Martin L., and Jarcn M. Diamond. 1975. Ecology and
evolution of communities. Belhnap Press of Harvard
Univ. Press, Cambridge, Mass. 545 pp.

Cook, C. D. K. , B. J. Gut, K. M. Rix, J. Schneller, and M.
Seitz. 19 74. Water plants of the world. A manual
for identification (if t:he genera of freshwater macro-
phytes. Dr. W. Junk b.v.. Pub., The Hague. 561 pp.

155

Coulson, Jack R. 1971, Proj'.nosis for control of water hya-
cinth by arthropods. Hyacinth Control J. 9(1): 31-3-^.

Cuyler, R. Duncan. 1958. The larvae of Chauliodcs latreille
(Megaloptera ; Corydalidae) . Ann. Entomol . Soc7 AmeF^
51(6) :582-586.

DeBenedictis , Paul A. 1973. On the correlations between
certain diversity indices. Amer . Natur. l''^7(954)-
295-302.

Del Fosse, Ernest S. 1975. Interaction between the waterhy-
acinth mite, Orthogalumna terebrantis Wallwork, and the
mottled weevil^ Neochetina eichhorniae Warner. Ph.D.
dissertation, UnTv'. of Florida, GaTne¥ville. 193 pp.

DeLoach , C. J. 1975. Identification and bioloj^ical notes

on the species of Neochetina that attack Pontederiaceae
in Argentina. Coleop. BuIT. 29 (4) : 25 7-265 .

Dymond. G. C. 1948. The water-hyacinth: a Gindcrella of

the plant world. Pages 221-227 in .1 . P. J. Van Vurens ,
ed. Soil fertility and sewage. Faber and Faber, Ltd.,
London .

Edden, A. C. 1971. A measure of species divorsitv related

to tlie lognormal distribution of individuals among species
J. Exper. Mar. Biol. Ecol. 6:199-20^5.

Fager, E. VJ. 1972. Diversity: a sampling studv. Amer.
Natur, 106(949) :293-310.

Ferguson, Frederick F. 1968. Aquatic v;eeds and man's well-
being. Hyacinth Control J. 7:7-11.

Freeman, T. E., F. W. Zettler and R. Charudattan, 1974.

Phytopathogens as biocontrols for aquatic v.^eeds . PANS
20(2)':181-184.

Coin, C. J. 1943. The lower vertebrate fauna of the water
hvacinth community in northern Florida. Proc . Fla.
Acad. Sci. 6 (3-4) : 143- 153 .

Good, I. J, 1953. The population frequencies of species

and the estimation of population parameters. Biometrika
40:237-264.

Gordon, Robert D., and J. R. Coulson. 1969. Report on field
observations of arthropods on water hyacinth in Fla.,
La., Tex. Aquatic Plants Control Prog., U. S, Army
Engineer, Vicksburg, Miss. Tech. Rep. 6:B3-B37.

156

Gowanloch. James Nelson. 19A4. The economic status of the
water hyacinth in Louisiana. La. Con.servationis t 2-
3, 6, 8.

Green, Roger H. 1971. A multivariate statistical approach

to the Hutchinsonian niche: bivalve mulluscs of Central
Canada. Ecology 52 (4) : 543-556 .

Haller, William T., and D. L. Sutton. 1973. Effect of pH
and high phosphorus concentrations on growth of water-
hyacinth. Hyacinth Control J. 11:59-61.

Haller, W. T., E. B. Knipling and S. H. West. 1970. Phos-
phorous absorption by and distribution in water hya-
cinths. Proc. Fla. Soil and Crop Sci. Soc . 30:65-68.

Hansen, K. L., E. G. Ruby and R. L. Thompson. 1971. Trophic
relationships in the water hyacinth community. Ouart.
J. Fla. Acad. Sci. 34(2) : 107-113 .

Heck, K. L. , Jr., G. van Belle and D. Simberl of f . 1975.

Explicit calculation of the rarefaction diversitv mea-
surement and the determination of sufficient sample size
Ecology 56:1459-1461.

Herring, Jon L. 1948. Taxonomic and distributional notes on
the Hydrometridae of Florida (Hemiptera) . Fla. Entomol.
31(4) :112-116.

Herring, Jon L. 1950a. The aquatic and semiaquatic Hemiptera
of northern Florida. Part 1. Gerridae. Fla. Entomol.
33(1) :23-32.

Herring, Jon L. 1950b. The aquatic and semiaquatic Hemiptera
of northern Florida. Part 2: Veliidae and flesoveliidae .
Fla. Entomol. 33(4) : 145- 150 .

Herring, Jon L. 1951a. The aquatic and semiaquatic Hemiptera
of northern Florida. Part 3: Nepidae, Belos tomatidae ,
Notonectidae , Pleidae and Corixidae. Fla. Entomol.
34(1) :17-29.

Herring, Jon L. 1951b. The aqiaatic and semiaquatic Hemiptera
of northern Florida. Part 4: Classification of habi-
tats and keys to the species. Fla. Entomol. 34(4) :146-
161.

Hitchcock, A. E., P. W. Zimmerman, H. Kirkpatrick, Jr. and

T. T. Earle. 1949. Water hyacinth: its growth, repro-
duction and practical control by 2,4-D. Contrib. Boyce
Thompson Inst. 15 ( 7) : 363-401 .

157

Hitchcock, A. E., P. \-l . Zinmierman , II. Kirknatrick, Jr., and
T. T. Earle. 1950. Growth and reproduction of water
hyacinth and alligator weed and their control by means
of 2,4-D. Contrib. Boyce Thompson Inst. 16 (3) : 91- 130 .

Holm, L. G. , L. W. Weldon, and R. D. Blackburn. 1969.
Aquatic weeds. Science 166:699-709.

Horn, G. H. 1880. Synopsis of the Dascyllidae of the United
States. Trans. Amer. Entomol . Soc . 8 : 76-114 .

Hurlbert, Stuart H. 1971. The nonconcept of species diver-
sity: a critique and alternative parameters. Ecoloev
54:577-585.

Ingersoll, Jean M. 1964. Historical examples of ecological
disaster: The water hyacinth; the copper basin. Office
of Civil Defense, Dept. of Defense, Report HI-360-RR/A1- 2 .

Johnson, Clifford, and Minter J. Westfall, Jr. 1970. Diag-
nostic keys and notes on the daniselflies (Zvgoptera)
of Florida. Bull. Fla. State Hus. 15(2):45-89.

Katz, Edith E. 1967. Effects of the chemical eradication of

water hyacinths on associated aquatic fauna. M.S. thesis,
Stetson Univ., Deland, Fla. 52 pp.

Kelsey, H. P., and W. A. Dayton. 1942. Standardized plant names
J. Horace McFarland Co., Harrisburg, Pennsylvania. 675 pp.

Klorer, J. 1909. The water hyacinth problem. J. Assoc. Eng .
Soc. 42:33-48.

Knipling, E. B., S. H. West and W. T. Haller. 1970. Growth
characteristics, yield potential, and nutritive content
of water hyacinths. Proc. Fla. Soil and Crop Sci. 30:
51-63.

La Rivers, Ira. 1948. A new species of Pelocoris from Nevada,
with notes on the genus in the United States. Ann.
Entomol. Soc. Amer. 41:371-376.

La Rivers, Ira. 1970. A new species of Pelocoris femoratus
(Pal isot-Beauvois) from Florida (Hemiptera : Naucoridae}".'
Biol. Soc. Nev. Occas. Papers 26:1-''^-.

Leech, H. B., and H. P, Chandler. 1956. Aquatic Coleoptera.
Chap. 13 in R. L. Usinger, ed. Aquatic insects of Cali-
fornia. Univ. California Press, Berkeley.

Lynch, J. J., J. E. King, T. K. Chamberlain, and A. L. Smith,
Jr. 1947. Effects of aquatic vjeed infestations on the
fish and wildlife of the Gulf states. U. S. Dept.
Interior, Fish/Wildlife Serv., Special Sci. Report No. 39.

158

MacArthur, R. H., and E. 0. VJilson. 1967. The tlieory of

island biogeography . Princeton Univ. Press, Princeton
N. J. 204 pp.

Margalef, R. 1969. Diversity and stability: a practical
proposal and a model of interdependence. Brookhaven
Symp. Biol. 22:25-37.

May, Robert M. 1975. Patterns of species abundance and
diversity. In, M. L. Cody and J. M. Diamond, eds .
Ecology and evolution of communities. Belknap Press
of Harvard Univ, Press, Cambridge, Mass,

McFadden, Max W. 1967. Soldier flv larvae in America north
of Mexico. Proc. U. S. Nat. Mus . 121 (3569) : 1-62 .

Mcintosh, Robert P. 1967. An index of diversity and the
relation of certain concepts to diversity. Ecology
48(3) :392-404.

Mitchell, D. S. 19 74. Aquatic vegetation and its use and
control. UNESCO, Paris. 135 pp.

Monk, C. D. 1967. Tree species diversity in the eastern
deciduous forest with particular reference to north
central Florida. Am. Natur. 101:173-187.

Montgomery, B. E. 1944. The distribution and relative sea-
sonal abundance of the Indiana species of Agrionidae
Proc. Ind. Acad. Sci. 51:273-278.

Morris, R. F. 1960. Sampling insect populations. Annu.
Rev. Entomol. 5:243-264.

Morris, Thomas L. 1974. Water hyacinth Eichliornia crassipes
(Mart.) Solms : Its ability to invade aquatic ecosys-
tems of Payne's Prairie Preserve. M.S. "thesis, Univ.
of Florida, Gainesville. 135 pp.

Morrison, Donald F. 1967. Multivariate statistical methods.
McGraw-Hill, New York.

Muenscher, W. C. 1967. Aquatic plants of the United States.
Comstock Publ. Co., Inc., Ithaca, New York. 374 pp.

Mulrennan, John A. 1962. The relationship of mosquito

breeding to plant production. Hyacinth Control J. 1:6-7.

Needham,' J. C, and M. J. Westfall, Jr. 1955. A manual of
the dragonflies of North America (Anisoptera) including
the Greater Antilles and the provinces of the Mexican
border. Univ. California Press, Berkeley. 615 pp.

159

O'Hara, James. 1961. The i nvertGhrate fauna associated with
water hyacinths in South Florida. M.S. thesis, Univ.
Miami, Florida. 66 pp.

O'Hara, James. 1968. Invertebrates found in water hyacinth
mats. Quart. J. Fla. Acad. Sci. 30 (1) : 73-80 .

Patrick, R. 1954. Diatoms as indication of river change.
Proc. Ind. Waste Conf. 9th, Purdue Univ. Eng . Exten
Serv. 87:325-330.

Peet, Robert K. 1974. The measurement of species diversity.
Annu. Rev. Ecol. and Syst. 5:285-307.

Peet, Robert K. 1975. Relative diversity indices. Ecoloev
56:496-498.

Penfound, VJ. T., and T. T. Earle. 1948. The biology of the
water hyacinth. Ecol. Monog. 18:447-472.

Pennak, Robert W. 1953. Fresh-water invertebrates of the
United States. Ronald Press Co., New York. 769 pp.

Perkins, B. D. 19 72. Potential for waterhyacinth management
with biological agents. Proc. Annu. Tall Timbers Conf.
on Ecol. Anim. Control by Habitat Management, Feb. 24-25
1972:53-64.

Perkins, B. D. 1973. Preliminary studies of a strain of the
waterhyacinth mite from Argentian. C.I. B.C. Misc Publ
6:179-184.

Perkins, B. D. 1974. Arthropods that stress waterhyacinth
PANS 29(3) :304-314.

Pielou, E. C. 1966a. The measurement of diversity in differ-
ent types of biological collections. J. Theoret. Biol.
13:131-144.

Pielou, E. C. 1966b. Shannon's formula as a measure of
species diversity: its use and misuse. Amer . Natur
100:463-465.

Pielou, E. C. 1969. An introduction to mathematical ecology.
Willey-Interscience, New York. 286 pp.

Pieterse, A. H. 1974. The water hyacinth. Trop . Abstr.
29(2) :X263-X483.

Poole, R. W. 1974. An intorduction to quantitative ecology.
McGraw, New York. 532 pp.

Preston, F. W. 1948. The commonness, and raritv, of species
Ecology 29(3) :254-2S3.

160

Preston, F. W. 1958. Analysis of the Audohon Christmas

counts in terms of the lognormal curve. Ecolopy 39(A)-
620-624. "

Preston, F. W. 1962. The canonical distribution of common-
ness and rarity. Ecology 43:185-215, 410-432.

Price, Peter W. 1975. Insect ecology. John Wiley and Sons,
New York. 514 pp .

Raynes , J. J. 1964. Aquatic plant control. Hyacinth Control
J. 3:2-4.

Robson, T. 0. 1974. Mechanical control. Pages 72-84 in

D. S. Mitchell, ed. Aquatic vegetation and its use~~and
control. UNESCO, Paris.

Sager, P. E., and A. D. Hasler. 1969. Species diversity in
lacustrine phy toplankton. I. The components of the
index of diversity from Shannon's formula. Amer . Natur.
103:51-59.

Sanders, H. L. 1968. Marine benthlc diversity: a compara-
tive study. Amer. Natur. 102:243-232.

Seabrook, E. L. 1962. The correlation of mosquito breeding
to hyacinth plants. hyacinth Control J. 1:18-19.

Sheldon, Andrew L. 1969. Equitability indices: dependence
on the species count. Ecology 50:466-467.

Simberloff, D. 1972. Properties of the rarefaction diver-
sity measurement. Amer. Natur. 106:414-418.

Simpson, E. H. 1949. Measurement of diversity. Nature 163:
688.

Small, J. K. 1933. Manual of the southeastern flora. Univ.
North Carolina Press, Chapel Hill. 1554 pp.

Spencer, N. R. 1973. Insect enemies of aquatic weeds. Proc .
3rd Int. Symp. Biol. Control of Weeds: 39-47.

Spencer, N. R. 1974. Insect enemies of aquatic weeds.
PANS 20(4) : 444-450.

Stimac, J. L., and K. L. Leong. 1977. Factors affecting

chironomid larval abundances in three vertical aquatic
weed habitats. Environ. Entomol. 6 (4) : 595-600 .

Stodola, Jiri. 1967. Encyclopedia of water plants. T. F. H.
Publications, Jersey City, New Jersey. 368 pp.

161

Stout, Jean, and JoHtt Vandermeer . 19 75. Coniparison of species
richness for stream- inhabit] ng insects in tropical and
mid-latitude streams. Amer . Natur. 1 09 (967) : 263-280 .

Strong, Donald R. , Jr. 1974a. The insects of British trees:

Community equilibration in ecological time. Ann. Missouri
Bot. Card. 61:692-701.

Strong, Donald R. , Jr. 1974b. Rapid asymptotic species

accumulation in phytophagous insect communities: the
pests of cacao. Science 185 : 1064-1966 .

Sutton, D. L. , and R. D. Blackburn. 1971a. Uptake of copper
by water hyacinth. Hyacinth Control J. 9(l):18-20.

Sutton, D. L., and R. D. Blackburn. 1971b. Uptake of copper
by parrotfeather and water hyacinth. Proc . 24th Annu.
S. Weed Sci. Soc . : 331.

Tabita, Angelo, and John W. Woods. 1962. History of hyacinth
control in Florida. !{yacinth Control J. 1:19-23.

Tilghman, Noah J. 1962. The value of water hyacinth in the
propogation of fish. Hyacinth Control J. 1:8.

Ultsch, Gordon R. 1971. The relationship of dissolved carbon
dioxide and oxygen to mi.crohabitat selection in Pseudo-
branchus striatus. Copeia 1971 (2) : 247-252 .

Ultsch, Gordon R. 1973. The effects of water hyacinths on
the microenvironment of aquatic communities. Arch.
Hydrobiol. 72 (4) : 460-473 .

Usinger, R. L., ed. 1956. Aquatic insects of California.
Univ. California Press, Berkeley. 508 pp.

van Emden, H. F., and G. F. Williams. 1974. Insect stabil-
ity and diversity in agro-ecosystems. Annu. Rev. Entomol.
19:455-475.

Viosca. Percy, Jr. 1924. Report of the entomologist. Page

43 in Annual report of the Board of Health, Parish of New
Orleans and the City of New Orleans.

Wahlquist, Harold. 1969. Effect of water hyacinths and fer-
tilization on fish-food organisms and production of blue-
gill and redear sunfish in experimental ponds. Proc.
23rd Annu. Conf. Southeastern Assoc. Game and Fish
Commrs: 373-384.

VJahlquist, Harold. 1972. Production of waterhyacinths and

resulting water quality in earthen ponds. Hyacinth Con-
trol J. 10:9-11.

162

Wakefield, John W. , and William M. Reck, Jr. 1962. Effects
of water pollution on aquatic vegetation. Hvacinth Con-
trol J. 1:10.

Walker, Edmund M. 195 3. The Odonata of Canada and Alaska,
Vol. 1, Part 1, General Part II, The Zygoptera- -damsel-
flies . Univ. Toronto Press. 292 pp.

Wallace, J. B. 1968. Trichoptera. Pages S1-S19 in Frank
K. Parrish, ed. Keys to water quality indicative
organisms (Southeastern United States). Fed. Water Pol-
lution Control Admin. U. S. Dept. Agric.

Webber, H. J. 1897. The water hyacinth and its relation
to navigation in Florida. U. S. Dept. Agric. Bull

18:1-20.

Weber, Hans. 1950. Morphologische und anatomische Studien
uber Eichhornia crassipes (Mart.) Solms. Abhandlunger
der Mathematisch-Naturwisserschaf tlicher Klasse. Aca-
demic der Wissenshaf ten und div Literature. Mainz.
1950(6) :135-161.

Westfall, Minter J., Jr. 1957. A new species of Telebasis
from Florida (Odonata : Zygoptera) . Fla. EntomoTT 40(1) :
19-24.

Westlake. D. F. 1963. Comparisons of plant productivity.
Biol. Rev. 38:385-425.

Whittaker, R. H. 1965. Dominance and diversity in land plant
communities. Science 147:250-260.

I«Jhittaker, R. H. 1972. Evolution and measurement of species
diversity. Taxon 21:213-251.

Wilhm, Jerry L., and Troy C. Dorris . 1968. Biological param-
eters for water quality criteria. Bioscience 18(6):
477-481.

Wilhm, Jerry L. 1972. Graphic and mathematical analyses

of biotic communities in polluted streams. Annu. Pvev.
Entomol. 17:223-252.

Williams, C. B. 1964. Patterns in the balance of nature.
Academic Press. London. 324 pp.

VJirth, Willis W. , and Alan Stone. 1956. Aquatic Diptera.
Chapter 14 in R. I,. Usinger, ed. Aquatic insects of
California. Univ. California Press, Berkeley.

163

Wright, Mike, and Alvan Peterson. 1944. A key to the genera
of anisopterous dragonfly nymphs of the United States
and Canada (Odonata, suborder Anisoptera) . Ohio J. Sci.
44(4) . -151-166.

Young, Frank N. 1954. The water beetles of Florida. Univ.
Florida Press, Gainesville. 238 pp.

Young, Frank N. 1955. The type locality and habitat of
Hydroporus dixianus Fall (Coleoptera : Dytiscidae) .
Coleop. BulTT~9TTyT7-9.

Young, Frank N. 1956. A preliminary key to the species of
Hydrovatus of the eastern United States ^Coleoptera :
Dytiscidae). Coleop. Bull. 10(3):53-54.

Young, Frank N. 1961. Pseudosibling species in the genus
Peltodytes (Coleopte
Amer. 5^ni) : 214-222 .

Peltodytes (Coleoptera :Haliplidae) . Ann. Entomol. Soc.

Young, Frank N. 196 3. Two new North American species of
Hydrovatus with notes on other species (Coleoptera:
DytiscTdae). Psyche 70 (3) : 184- 192 .

Zeiger, Charles F. 1962. Hyacinth--obs truction to naviga-
tion. Hyacinth Control J. 1:16-17,

Zettler, F. W. , and T. E. Freeman. 1972. Plant pathogens

as biocontrols of aquatic weeds. Atiiui. Pvev. Phytopathol
10:455-470.

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165

BIOGRAPHICAL SKETCH

Juozas (Joseph) Kestutis Balciunas was born 3 October
1946 at Wurtzbiirg, Bavaria, Germany. The son of Drs . Jurgis
and Brone Balciunas, he emigrated to the United States in
1950 and became a naturalized citizen in 1960.

Upon graduation from St. Joseph's High School, Dover,
Ohio, in 1964, he entered John Carroll University, Cleveland,
Ohio, where, in 1969, he received his Bachelor of Science in
biology with a minor in chemistry. He then accepted a teach-
ing assistantship in the Biology Department at John Carroll
University and received his Master of Science degree in biol-
ogy in 1972. His Master's project involved the distribution
of odonate nymphs in an Ohio county.

In August of 19 71 he accepted a research assistantship
at the University of Florida, where he is currently fulfill-
ing the requirements for the degree of Doctor of Philosophy.
His dissertation project involves the abundance and diversity
of aquatic insect species found beneath v;aterhyacinths .

Joseph K. Balciunas is single. He is a member of the
Ecological Society of America and the Florida Entomological
Society.

166

I certify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality,
as a dissertation for the degree of Doctor' of Philosophy.

}:^^ Mi^^c.^

Dale H. Habeck, Chairman
Professor of Entomology

I certify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality,
as a dissertation for the degree of Doctor of Philosophy.

/?

C"

J(%ities E . Lloyd ^^
Professor of Entomology

I certify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality,
as a dissertation for the degree of Doctor of Philosophy.

Carr
Professor of Zoology

I certify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality,
as a dissertation for the degree of Doctor of Philosophy.

Thomas J. IjJ^lker
Professor of Entomology

I certify that I have read this study and that in my
opinion it conforms to acceptable standards of scholarly
presentation and is fully adequate, in scope and quality,
as a dissertation for the degree of Doctor of Philosophy.

Minter J., Westfaly, Jr. '/

Prof essor'-bf Eiitoniology''and Zoology

This dissertation was submitted to the (Graduate Faculty of

the College of Agriculture and to the Graduate Council, and

was accepted as partial fulfillment of the requirements for
the degree of Doctor of Philosophy.

December 1977

cA. o^ ■ <UAX'-

Dearyf/ College of Agriculture

DearT; Graduate School

UNIVERSITY OF FLORIDA

3 1262 08553 2900