Official Organ of the Florida Entomological Society
VOL. XXXII JUNE, 1949 No. 2
A NEW PAGE IN INSECTICIDAL PRODUCTION FOR THE
PROTECTION OF VEGETABLE CROPS
E. G. KELSHEIMER, Entomologist
Vegetable Crops Laboratory
Florida Agricultural Experiment Station
World War II was the impetus that started economic ento-
mology on its way to a broader and more efficient insect control.
In this country, DDT was the organic insecticide responsible
for all of this enthusiastic and fact finding research. DDT has
been the guinea pig and standard for all of our organic insecti-
cides, and practically every insecticide manufacturer has initi-
ated a program to produce a material superior to DDT. As a
result, we have many promising organic in the chlorinated
series, such as chlordane (chlordan to the chemists), dichloro-
diphenyl dichlorothane (DDD), methoxychlor, chlorinated cam-
phene, and benzene hexachloride (low gamma and essentially
pure gamma isomer base material). Of more recent introduc-
tion are the members of the phosphatic group-hexaethyl tetra-
phosphate, tetraethyl pyrophosphate and parathion. There still
is a large and promising array of insecticides known only by
their laboratory code numbers. Another group includes the
botanicals such as pyrethrum, rotenone, Ryania, Sabadilla, nico-
tine, and others, all of which play an important part in agri-
It has become a common expression among research workers
and representatives of manufacturers to remark "Am I con-
fused?" It is obvious why we have this confusion, but for-
tunately this picture is being cleared as quickly as time and
funds permit. As Garner said, "Every man after a certain
age is entitled to his conclusions and confusions."
1 Presidential address, 1948 meetings.
Mailing Date: July 19, 1949
54 THE FLORIDA ENTOMOLOGIST
VOL. XXXII JUNE, 1949 No. 2
THE FLORIDA ENTOMOLOGICAL SOCIETY
OFFICERS FOR 1948-49
President---......---.....--- ...--- .-----M. C. VAN HORN
Vice President .....-----------...... --------J. A. MULRENNAN
Secretary ..----....-....-------....---. LEWIS BERNER
Treasurer ---... --.-------------------G. W. DEKLE
Executive J. T. GRIFFITHS, JR.
Executive Committee .... ....... ...... ) C. F. LADEBURG
H. K. WALLACE ... ......-------...--....-..--.........-.. --- Editor
G. B. MERRILL -..--. ---..---.............Associate Editor
G. W. DEKLE.-----.....-.................--Business Manager
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VOL. XXXII-No. 2
There isn't one of us present that can't remember back when
the standard reply to an inquiry was, "if it is a chewing insect,
use arsenicals or cryolite, if a sucking insect, use nicotine." If
properly applied, a grower managed to produce a crop. Our
new organic and inorganics have not entirely replaced our old
insecticides because there still is a big demand for arsenicals,
cryolite, nicotine, pyrethrum and rotenone where their past
records have proven their value.
Enough time has now elapsed so that intelligent growers
and the public realize that DDT did not end their insect prob-
lems. Such is true with our other organic. Too many of these
are specific for a limited number of insects, some even to species
within a genus. The growers' as well as the workers' ideal is
one compound that is general for all chewing and sucking in-
sects. We don't have any such material, so therefore, the doors
have not been closed to research seeking for new and more
I dare say that more emphasis has been placed upon the
importance of toxicity to man, toxicity to plants and harmful
residues in the past five-years than in all of the time previous.
Is it due to the fact that we have become more conscious of
these factors or is it because our older materials did not present
these problems? Every one understands the tolerance placed
upon certain fruits and vegetables and this was used as a
criterion for our research. We know that all insecticides should
be treated as poisons and applied with care. We also know
that many of our old insecticides were phytotoxic and were
just not applied to plants. Harmful residues were explained
under the heading of tolerance. Residues in the soil are an
important factor. My own classic example is the application
of lead arsenate in my garden to kill the grubs. I thought that
the application would not last long in a sandy soil but would
leach out. Such was not the case. I couldn't grow anything
on it for three years. I have since learned that perhaps I could
have corrected the problem but it was my garden and I didn't.
You see, we had our same problems before with the older
materials, but perhaps did not place too much importance
thereon. In many parts of Florida, the custom has been to clear
off and prepare new land each year for a crop. It is true this
did hold down certain insect populations, plant diseases, and
prevented any soil residue problems. With new land each year
THE FLORIDA ENTOMOLOGIST
becoming more scarce, growers are using the same fields over
Perhaps more alarm has been shown over the harmful resi-
dues left in the soil after heavy applications of organic for
both soil inhabiting and aerial types of insects than ever before.
Some very disquieting reports have been issued from the north-
ern states on harmful effects of DDT in the soil to certain crops.
Florida being an insecticide manufacturers paradise has
used great quantities of organic materials for the control of
certain soil inhabiting insects. DDT was the first material used
in the soil in any great quantities. Some greenhouse tests with
peppers showed no significant difference up to 5,000 pounds
actual material per acre. Tomatoes were more sensitive, sig-
nificant reduction beginning with 800 pounds actual per acre.
In a laboratory test, lettuce was grown in soil containing vary-
ing amounts of DDT up to 500,000 lbs. actual DDT per acre.
There was no difference in the growth and appearance of the
plants up to 50,000 pounds. The soil with the high amount
was like putty, being half sand and half 50W DDT. This amount
failed to kill the plants and after a month's time when the
experiment was discarded, one dwarfed lettuce plant was re-
moved to good soil, and it grew and produced a normal head of
lettuce. These are all tremendous amounts of material, but we
were attempting to reach a toxic range. Under our Florida
conditions, it is doubtful if we will have to contend with a
residual effect in the soil. We have not tested all of the new
materials by any means and perhaps never will as it is a long
process. You grow a crop under these conditions and follow
up with the same or a different one to see how long these effects
may be noted. Chlordane has been used up to 50 pounds per
acre with no effect on the germination of seedlings of vegetables
in seedbeds. The tobacco men have a different story as injury
Phytotoxicity is of primary concern to every one. The new
materials have a specificity toward plants. Some plants may
be treated with safety at any time. Others have to be perfectly
dry or burn will result to the new growth. This factor is one
of the reasons why we like to apply our insecticides in the
afternoon and evening. Phytotoxicity does not have to appear
as damaged plants but may show only as decrease in yield. A
field of cucurbits may look green and healthy and the grower is
real proud of his insect control. Because he has not run any
VOL. XXXII-No. 2
check he does not realize how many hampers are missing at
the end of the harvest.
We briefly mentioned tolerance limits but now we think of
our materials in terms of toxicity to man. All insecticides are
poisons, but some are many times more toxic than others. It
is this toxicity to man that is of the utmost concern to all. New
materials appear so fast that they are not fully tested so, with
many, there is still a question of doubt as to their safeness.
Many of the new insecticides break down fairly rapidly under
our sunlight conditions, thus enabling us to give the grower
a little wider range of latitude of safety between the last appli-
cation and harvest.
All growers want to combine their insecticides and fungi-
cides and frequently include secondary nutritional elements.
Think of the fungicides which include the carbamates and cop-
pers and then the insecticides of the chlorinated and phosphate
group-not to mention cryolite and the arsenicals. To this
may be added the nutritional such as iron, manganese, zinc,
boron and copper, if no copper spray has been used. One time
a grower called up and inquired about the advisability of mix-
ing a carbamate and copper plus a chlorinated insecticide, some
iron, manganese, zinc and then some ammonia. I told him I
never tried such a combination and certainly would not advise
it. He then said "I put her on". I am no longer confused,
Compatibility of material is of utmost importance. We think
of compatibility in chemical, physical and biological terms.
The manufacturers have screened their materials and stated
on their labels that such a material can be used in safe com-
bination with some and not with others, generally those of an
alkaline nature. We are interested in all three phases because
a material cannot settle out, curdle or in other ways mess up
a spray machine. Particularly are we interested in the bio-
logical compatibility as it affects the control of our insects and
fungi. Some very interesting phenomena have shown up in
some of our carbamate and chlorinated combinations. Very
definite chlorosis is visible, sometimes within 24 hours after
application. This occurs on new growth of fast growing plants.
It is not evident on older and slow growing plants. Its effect
upon yield has not been evaluated.
Recently, I was asked by a group of interested citizens what
was my opinion of the value of mosquito control and its effect
THE FLORIDA ENTOMOLOGIST
upon wild life. My answer was in favor of it because it has
been found that DDT, used with care, is not harmful to wild
life. In this same connection, the bee keepers were quite alarmed
about the insecticides used on cucurbits. They need not be, if
the growers will cooperate and apply their insecticides on
cucurbits in the afternoon and evening. Bees do not remain
in cucurbit fields long after noontime. Applications that are
made will be on old flowers. The new ones that open the next
day are the ones that will be visited by the bees and there is
less likelihood of the bees picking up the poison.
THE COMMERCIAL ANGLE
As previously stated, Florida uses a tremendous amount of
insecticides. Thus the economic stake is considerable for every
company is interested in placing its material before the public
eye. Florida offers a year around growing program, something
we often forget. Little if anything of commercial vegetable im-
portance is grown in central and south Florida from June to
August. But in northern Florida, crops are in full swing at
that time. I mention this to show how complicated the picture
is for the insecticide representative. At times the research man
in particular sections is "talking to himself"-how about this
representative I have mentioned? At times I become quite
critical of some of the methods used to put across a material,
but when I calm down, I realize they are in it for the money.
Sometimes a product is put on the market prematurely. We
all realize the lack of wisdom in doing this. We research men
are likely to forget the amount of capital invested in a new
product. We don't like the high prices demanded just because
the company wants its returns from the pilot plant venture.
This isn't the entire picture by any means. When a product is
considered ready for the trade, a substantial inventory of the
material must be in each district or area. Suppose a change
in formulation is necessary before the present inventory is
moved, then considerable readjustment must be made. This
means then a re-education of that particular representative's
clients, and may cause considerable grumbling.
The commercial representative can help the research work
by discouraging the too frequent and sometimes promiscuous
use of high priced insecticides. Many of these are sold on credit.
A loss to one is a loss to all.
VOL. XXXII-No. 2
In summing up the manufacturer's side of the picture, they
can help the research worker by adequately screening out their
materials, giving generous samples for investigational work,
and allowing the material to be tested a normal gestation period
(a term used by my good friend, George Decker). Curious
as it may seem, some concerns still are hesitant to supply ade-
quate samples. One very well known firm just sent tiny ex-
hibition samples and then expected full field reports back on
the material. Those samples went in the waste basket. We
generally ask for enough material to run two seasons; in that
way we can test a batch lot in the fall and in the spring.
THE ROLE OF THE RESEARCH WORKER
The state research worker and the manufacturers work
hand in hand. It is our duty to adequately and carefully evalu-
ate material sent to us for experimental investigation. By that
we mean a product ready for use if not already on the market.
We cannot serve as screening depots and test a number of ex-
perimental materials. Florida is a wonderful testing ground
by reason of the fact that crop production is a year around
proposition somewhere in the state.
New materials appear so fast that we are able only to hit
the high spots and are happy to report in a preliminary way
on the toxicity to insect, phytotoxicity, toxicity to man, residual
effects in the soil and then hope that we can come back later
and do a more thorough job of evaluating the materials.
Everyone present knows how complex the situation is. It
is no longer a job for the entomologist. He runs into problems
that require the assistance of chemists, plant pathologists, plant
and insect physiologists, toxicologists, ecologists, etc. Just to
touch lightly on the last subject, the ecological relationship, a
material may be specific for an insect in one section of the coun-
try and fail miserably elsewhere. This same condition may be
true within a state.
In our rush, we have not had the time to evaluate these new
materials under various weather conditions. Some materials
respond well during dry weather, others in wet weather. Ap-
parently, from recent tests conducted, a material needs only
to be on the plant an hour's time to prove effective. We know
of one material, very effective for subterranean insects, whose
efficacy is increased following artificial watering or a light
shower. This same material applied to a plant for aerial types
THE FLORIDA ENTOMOLOGIST
of insects is again apparently activated by frequent rains and
goes so far as to reduce the yield of the fruit. I mention these
illustrations, as perhaps some of the reasons why a material
may fail after apparently proving itself a good insecticide.
In conclusion, we have presented some of the facts as we
see them. Yes, we are still confused. New products continue
to be called to our attention. A new product is a new problem
and limited time does not permit us to break down this confusion.
We all do the best we can. We supply the manufacturers and
growers with the best answers that only limited data provide.
The challenge of the "new" is very demanding. We have turned
a new page in insecticidal production and with plenty of energy
and a dash of luck, we can keep pace and supply the information
they are asking us to give.
OBSERVATIONS ON THE INCREASE OF APHIDS ON CELERY
FOLLOWING THE APPLICATION OF COPPER A
COMPOUND AS A FUNGICIDE
By J. W. WILSON
Central Florida Experiment Station
For a considerable period of time the fact that application
of certain materials to various crops tends to be followed by
an increase of one or more insects, has been generally recog-
nized by Entomologist and Plant Pathologist. For example,
Folsom in 1927 attributed the initial infestations of aphids on
cotton following the application of calcium arsenate to the posi-
tive phototrophic reaction of the winged females. Bonde and
Snyder (1946 and 1947) reported a significant increase of aphid
populations in potato plots sprayed with Bordeaux Basic Copper
Sulfate, Karbam Z, Karbam Z and soap and Dithane. They
also observed that aphid populations are often greater in fields
sprayed with Bordeaux than in those receiving applications of
neutral copper fungicide. Wylie (1948) reporting on his work
on the control of aphids on celery with insecticides combined
with fungicides stated that the aphid populations on the plots
treated with Bordeaux were significantly greater than on the
untreated plots. Thompson (1936, 1937 and 1940) observed
the buildup of purple scale on citrus following the applications
of Bordeaux. He found that the scale populations increased
with the amount of residue deposited on the citrus leaf, and
VOL. XXXII-No. 2 61
that the increase in scale population was entirely due to the
protection afforded the young scale crawlers by the residue, as
was illustrated by the fact that roadside trees where road dust
was deposited on the leaves had a heavier infestation of purple
scale than trees away from the road that did not receive a deposit
of road dust. More recently the buildup of aphids and mites
on cotton following the application of DDT has been reported
by Loftin (1945) and others. Ruehle (1947), reporting on
fungicides for the control of late blight on potatoes, stated that
leaf miner infestations were heaviest on plots sprayed with the
dithiocarbamates as compared with plots treated with copper
and zinc chromate.
Moore (1935) studied'the reaction of the potato aphid to
potato leaves sprayed with bordeaux and concluded that the
winged females were attracted to the bordeaux sprayed leaves
because of the greater amount of light reflected by the bordeaux
sprayed leaves. Aphids caged on sprayed and unsprayed leaves
did not increase faster on the sprayed leaves. There was no
difference in the wave length of light reflected from the sprayed
and unsprayed leaves, but more intense light was reflected from
the bordeaux sprayed leaf surface. When fast green dye was
combined with 5-5-50 bordeaux and applied to potato leaves
the number of aphids was less than on the bordeaux sprayed
leaves but greater than on unsprayed leaves.
During the fall of 1947 an experiment was conducted on pascal
celery in which Fermate and Zerlate at one pound each to 100
gallons of water and Copper A Compound at five pounds to 100
gallons were applied at 7-day intervals as fungicides. Triton
B 1956 at the rate of 160 cc. per 100 gallons was added to both
fungicides as a spreader sticker. Eleven insecticides were com-
bined with each of the fungicides when the aphid population
became large enough to require treatment. The celery plants
were transplanted to the field on October 28 and the application
of fungicides was begun seven days later with a total of twelve
fungicide applications for the season. Insecticides were com-
bined with the fungicides December 9, 22 and January 16. The
spray materials were applied by means of a pressure sprayer
operating at 300 pounds pressure. The spray machine was
equipped with a six row boom having three nozzles to each row.
This equipment applied the spray material at the rate of 105
gallons per acre. The plots were arranged in a randomized
block design with six replications. Aphid counts were made
THE FLORIDA ENTOMOLOGIST
at approximately 7-day intervals beginning December 2, by re-
cording the aphids on ten trifoliate leaves plucked at random
from the two center rows of each plot. No other insect attacked
the celery during the growing season. Very light and widely
scattered infestations of red spider were found a few days be-
fore the celery was harvested. A sample of the aphids was
identified by Dr. A. N. Tissot as Aphis gossypii Glover.
Table 1 lists the insecticides, the concentration and the source
of the insecticides used.
TABLE 1.-LIST OF THE INSECTICIDES, CONCENTRATIONS AND SOURCE OF
THESE INSECTICIDES APPLIED TO PASCAL CELERY IN COMBINATION WITH
FFRMATE-ZERLATE AND COPPER A COMPOUND DURING THE GROWING
Treat- per 100
ment Material Gallons Source
1 25% DDT Emulsion ..--...... 1 qt. Rohm & Haas Company
2 6% gamma isomer Ben-
zene Hexachlor .........-- 4 lbs. California Spray-Chemical Co.
3 25% gamma isomer BHC 1 lb. California Spray-Chemical Co.
4 48% Chlordane Emulsion. 2 qts. U. S. Rubber Company
5 40% Chlorinated Cam-
phene ................................ 4 lbs. Pennsylvania Salt Company
6 50% H.E.T.P. --~..... -- ..- / pint California Spray-Chemical Co.
7 50% T.E.P.P. ..................... /2 pint California Spray-Chemical Co.
8 50% Methoxy DDT ............ 4 lbs. E. I. Du Pont
9 25% Parathion .................... Y lb. American Cyanamid Company
10 25% DDD Emulsion ......... 2 qts. Rohm & Haas Company
11 40% Colloidal DDT .......... 1 qt. Michigan Chemical Company
12 Check ....................................
Table 2 presents a summary of the aphid counts made during
the growing season. From this table it will be noted that with
a few exceptions the aphid population on the plots treated with
Copper A Compound is considerably greater than on the plots
treated with Fermate-Zerlate. This is true in the plots receiving
the two fungicides alone, as well as in the plots where the in-
secticides were combined with the fungicides. It will also be
noted that the aphid population was not high at any time during
the growing season.
In an effort to account for this larger aphid population on
the plots receiving Copper A Compound as compared with the
plots treated with Fermate-Zerlate, pH determinations were
made of the water used to make up the spray materials, and of
the spray mixtures. The pH of Copper A Compound mixtures
TABLE 2.-APHID POPULATIONS AT 7-DAY INTERVALS ON PASCAL CELERY TREATED WITH FERMATE-ZERLATE AND COPPER A
COMPOUND IN COMBINATION WITH VARIOUS INSECTICIDES DURING THE CROP SEASON 1947-48.
Date Treatment Number
1 2 3 4 5 6 7 8 9 10 11 12
Cu 56 35 71 75 52 78 106 61 65 58 100 55
12/2 F-Z 63 78 43 96 65 113 :2 33 72 54 58 53
Cu | 70 84 64 132 85 46 :0 79 22 70 48 |. 211
12/16 F-Z 41 49 51 44 25 36 :!; 77 11 7 27 139
Cu 45 133 106 176 113 173 110 346 95 | 97 72 274
12/22 F-Z 93 38 61 45 57 36| 5 92 17 47 60 241
Cu 67 146 82 71 106 118 12) 116 54 43 34 348
12/30 F-Z 73 56 63 66 57 70 72 84 93 43 60 196
Cu 112 161 126 250 70 138 1.5 104 64 47 79 342
1/6 F-Z 71 65 81 113 58 68 81 55 80 13 40 151
Cu 150 148 308 97 55 155 21;5 104 143 31 35 297
1/12 F-Z 92 91 87 136 38 48 91 34 36 16 55 82
Cu 135 71 80 170 121 225 118 122 18 29 172 217
1/1 F-Z 48 28 21 77 27 49 30 28 41 38 31 45
Cu 67 62 1 51 199 48 77 47 37 18 13 39 77
1/26 F-Z 14 21 7 29 16 13 11 23 29 7 16 13
Cu 69 59 51 259 118 111 71 51 1 33 30 80 18
2/2 F-Z 17 16 18 114 30 95 11 25 33 44 26 9
Cu 32 49 51 71 72 46 50 46 55 62 95 72
2/10 F-Z 64 63 24 51 40 51 34 26 74 31 34 20
60 50 45
34 11 14
25 1 31 37 | 67 39 57 | 63
24 18 38 79 35 27 I 57
THE FLORIDA ENTOMOLOGIST
was very slightly lower than the pH of the Fermate-Zerlate
mixtures. Furthermore, there was no difference in the pH
value of samples of the plant juices from the plots treated with
the two fungicides. Thus it would appear that the pH of the
spray mixtures or the pH of the plant juices had no influence
on the aphid populations in these plots. It has been suggested
that the Copper A Compound mixture might destroy the para-
sitic fungi attacking aphids and thus allow a more rapid in-
crease in the numbers of aphids on the plots sprayed with
Copper A Compound. No differences in the number of aphids
killed by parasitic fungi was observed in the plots treated with
these fungicides during the growing season. However, such
an effect upon the parasitic fungi might have been unobserved
because the aphid population was comparatively light in all of
the plots. The amount of light reflected by leaves sprayed with
these fungicides has yet to be measured. It has also been sug-
gested that the applications of copper might have produced a
physiological condition favorable to the multiplication of aphids.
Plans have been made to test this hypothesis during the present
Bonde, Reiner and Everett Snyder, 1946. Comparison of different organic
and copper fungicides and some combinations of fungicides with DDT
for the control of potato diseases and insects. Amer. Potato Jour.
23: 12; 415-25.
.1947. Control of late blight and early blight. Annual
Report, Maine Agr. Exp. Sta. for the year ending June 30, 1947. p. 268
Folsom, J. W. 1927. Calcium arsenate as a cause of aphid infestations.
Jour. Econ. Ent. 20: 6; 840-43.
Loftin, U. C. 1945. Results of tests with DDT against cotton insects in
1944. U.S.D.A. Bureau of Ent. and Plant Quarantine. E Series 657.
Moore, J. B. 1935. Studies of the reaction of potato to sprayed and un-
sprayed potato leaves. Jour. Econ. Ent. 38: 2; 436-42.
Ruehle, G. D. 1947. Control of potato diseases in Dade County. Fla. Agr.
Exp. Sta. Annual Report for 1946. p. 197.
Thompson, W. L. 1936. Control of purple scale and whiteflies with lime-
sulfur. Fla. Agr. Exp. Sta. Annual Report for 1935. p. 100.
.1937. Control of purple scale and whiteflies with lime-
sulfur. Fla. Agr. Exp. Sta. Annual Report for 1936. p. 114.
1940. Control of purple scale and whiteflies with lime-
sulfur. Fla. Agr. Exp. Sta. Annual Report for 1939. p. 145.
Wylie, W. D. 1948. Tests of new insecticides for the control of aphids in
the Everglades. Fla. Agr. Exp. Sta. Bulletin 446. p. 7.
VOL. XXXII-No. 2
A PRELIMINARY REPORT ON THE SNAIL DRYMAEUS
DORMANI IN CITRUS GROVES IN FLORIDA
JAMES T. GRIFFITHS, JR.
Citrus Experiment Station, Lake Alfred, Florida
An arboreal snail, Drymaeus dormani Binney, has been re-
ported in citrus groves in Florida for many years. Often,
growers have believed that the presence of these snails in their
groves has been of great benefit. No real effort has ever been
made to either substantiate or repudiate these claims. In the
spring of 1946, the author started a study of this snail in three
groves in Lake County and in one grove in Sumter County. The
following discussion reports these observations and is an attempt
to explain, in a preliminary way, the possible role of this snail
in citrus culture in Florida. Continued observations will be
necessary before more definite conclusions can be drawn.
In 1857, W. G. Binney (1)1 described a snail taken by O. J.
Dorman near St. Augustine as a new species, Bulimulus dormani,
and in 1878, he (2) made a more complete and accurate descrip-
tion. A complete bibliography on description and synonomy is
listed by Pilsbry (6) in his monograph on land shells written
in 1946 and Norris (5), in 1947, described the activities of this
snail in one grove in Lake County.
Following Binney's description, the snail was reported (3)
near the Matangas River, at Port Orange, at Oak Hill in Vo-
lusia County, and on the Florida west coast between Cedar Keys
and the Suwannee River. Simpson (8) in 1893, stated that he
found several hundred shells in a heavy hammock north of
the Manatee River, and that he also found the snail near Cun-
ningham in Volusia County. In 1906, Sellards stated that the
snail ranged as far north as the St. Johns River and south to
the Caloosahatchee River. Pilsbry (6) lists the snail in Alachua,
Duval, Marion, Webster, Manatee, Lee and Highlands counties.
A variety albidus was created by Wright (10) from collections
near Fatio in Volusia County, but considerable question is cast
upon the validity of such a classification. In 1948, the author
observed D. dormani in citrus groves in Lake, Sumter, Her-
nando, and Marion Counties and has reliable reports of its
presence in groves near DeLand in Volusia County. To the
1 Italic figures in parentheses refer to Literature Cited.
THE FLORIDA ENTOMOLOGIST
writer's knowledge, this species has not been reported south
of Lake Okeechobee, and its range is confined to Florida. Pils-
bry (6) stated that dormani is an apparent descendant of a
Mexican species, and that it probably migrated to Florida via
the southern United States in Pliocene times. It is, apparently,
not closely related to any West Indian species.
BIOLOGY IN CITRUS GROVES
In discussing a generalized land snail, Binney (2) stated
that they were usually vegetarians, that they laid their eggs
in summer in the soil, and that they tended to be especially
active at night or after a shower. During winter they hiber-
nated by secreting a membrane-like structure, the epiphragm,
across the opening of the shell. These generalities appear to
fit D. dormani very well. Oviposition has been found to occur
in the early part of the summer months. The onset of oviposition
may vary from year to year, but it apparently extends over
a period of six to eight weeks. In 1946, oviposition was well
started by June 1; in 1947, it was delayed until about June 25;
and in 1948, only a few eggs were seen by June 17. The onset
of oviposition is probably partially determined by the onset of
warm weather in the spring. However, there was an early
spring in 1948, and the snails became active as early as Feb-
ruary, but this did not result in early oviposition. This may
have been due to the extremely dry weather which was ex-
perienced in May and June of 1948.
The eggs are laid in groups which vary from only a few
to as many as 30, 40 or more. Since they are semi-buried, it
appears that some effort is made to deposit the eggs so that
leaves or other trash will partly cover them. They are laid
near the base of a tree and the author has never observed them
more than a few inches away from that general area. No data
has been obtained on the necessary incubation period. There
may be over a hundred eggs at the base of a tree and when they
hatch, the lower part of the tree trunk may be literally covered
with tiny snails measuring less than 2 mm. in diameter.
So far, the length of time required to reach maturity and
the total life span have not been determined. Some evidence
appears to indicate that the snails live at least three years, and
possibly longer. They attain a maximum size such that the
shell measures almost three centimeters in length. Tryon (12)
suggests that terrestrial snails usually require two years to
VOL. XXXII-No. 2
reach sexual maturity and that they live 6 to 8 years in cap-
tivity. Whether this applies to D. dormani will have to be
The densities of the snail populations in the groves under
observation have fluctuated from year to year. Heavy popu-
lations might occur for one or two years, and then this would
be followed by a low population for the next year. The trees
attain a slick appearance due to the feeding activities of the
snails and an idea of the number of snails present may be cal-
culated by the date when the trees are cleaned up. Where
snails are common, this has been observed as early as mid-July,
but when few snails are present, it has been delayed until as
late as November. Mortalities are often heavy during the win-
ter or fall months. In one grove there was a heavy population
in October, but they died off before cold weather and very few
snails lived to go into hibernation. During November and
December, it was almost impossible to find a live snail in the
grove. Cold weather may sometimes be a factor, but in this
latter instance snail mortality cannot be attributed to low tem-
peratures. Lack of foodmay have been a factor since the trees
were free of sooty mold by mid-July. For the present, however,
the reasons for the marked population changes from year to
year must remain unexplained.
The snails usually go into hibernation in December. They
seek shelter in cracks and crevices in the trees and under trash
at the base of the trees. A few, however, remain on the foliage
or on exposed limbs and go dormant there. They secrete a
membrane-like structure (the epiphragm) across the opening
of the shell, and securely attach themselves to some substratum.
They remain there until warm weather, when they appear to
become active at about the same time that the trees begin to grow.
EFFECTS OF SNAILS IN GROVES
The food habits of this snail have not been fully determined.
Binney (2) states that land snails are largely vegetarians, and
Pilsbry (6) describes a related species which feeds on minute
algae on the trees. D. dormani obviously eats sooty mold, and
it would appear that this was its main food source. Large
lichens on the limbs and trunks and entomogenous fungi on
white flies are not eaten, but green algal growth is removed
from the wood. In the late summer and fall of the year, all
the sooty mold may be gone so that the trees appear to have been
THE FLORIDA ENTOMOLOGIST
oiled. The leaves are slick and glossy, and the wood is smooth
and clean. The appearance of the wood is quite characteristic
and at any season will serve as an easy guide to the trees which
have or have recently had snail infestations.
In 1906, Sellards (7) discussed the fact that D. dormani re-
moved sooty mold. In fact, this was what made the snail a
valuable ally at the turn of the 20th century. At that time
fruit was not regularly washed and then packed as is the case
today. It was simply picked, put in a barrel, and shipped north.
The advent of the whitefly and its attendant sooty mold forced
the citrus man to wash his fruit before packing it. This added
a new and expensive operation. However, where the snails had
first cleaned the fruit, the washing was unnecessary. It is easy
to understand why growers desired to maintain snails in their
groves. The situation facing the grower today is entirely dif-
ferent, and different evaluations must be made of the snails
and their cleaning activities.
Some citrus growers believe that the snails actually eat the
scale insects on the trees, but the author has found no justifica-
tion for such a claim and Norris (5) stated that it was doubtful
that they ate scales. Purple and red scale populations have
been checked at regular intervals in three groves with snail
populations for more than two years. During that same period,
scale infestations were checked in other groves on similar pest
control programs. In these groves, zinc, copper and oil sprays
were not used and only sulfur was applied. The data are too
extensive to reproduce here and definite conclusions must await
additional study. However, some of the groves had relatively
heavy purple scale infestations and some had very light ones.
Groves with and without snails were in both categories, and it
could not be concluded that there were any less scales in the
snail infested groves. Florida red scales were not a problem
in any of them. In snail infested groves, a number of leaf
samples were divided as to those which had been cleaned of
sooty mold by the snails and those which had not. Less purple
scales were found on the clean leaves. The author cannot con-
clude that the scales were removed by the snails, but rather
that the lack of residue was the important factor and that as
suggested by Thompson (11) and Holloway (4), purple scale
is more prevalent in the presence of inert residues. It is pos-
sible that clean leaves may be a factor in maintaining low scale
infestations, and therefore that snail infested groves would be
VOL. XXXII-No. 2
expected to have less scales than other groves. Whether this
be true or not, scale insect infestations could not be considered
to have been a limiting factor in any of the groves involved.
No claims have been made by growers for the control of other
citrus insects. In general, it has been noted that insect popula-
tions were similar in groves both with and without snail popu-
lations when these groves were not sprayed with compounds
of zinc and copper, and with an oil emulsion. Thus, there were
usually low scale and purple mite infestations and sometimes
high rust mite incidence. These conditions are undoubtedly
related to the fact that a biological balance has been attained
such that scales and purple mites do not usually produce ex-
cessive injury. It is however, necessary to apply some sulfur
if the grower wishes to produce fruit free from rust mite injury.
The problem of melanose should also be considered. Al-
though no copper was sprayed in any of the snail-populated
groves discussed above, the author did not observe serious
melanose infection on oranges in either 1946, 1947, or 1948.
Excessive melanose was noted on grapefruit in one of the groves.
Although snails have been collected in abundance from the dead
wood, and it is possible that they may eat melanose spores, no
actual evidence of such has been obtained. It must also be
noted that snail activity is at a minimum during the spring,
when melanose control would be essential. Populations are low
at that time, and there is little evidence of any cleaning activity.
YIELD AND COST OF PRODUCTION DATA
It is difficult to obtain accurate production records and also
difficult to get the proper groves for comparisons. Table 1
shows yield and cost data for three groves in Marion County.
All are close together and are operated by the same production
man. The one with snails is the oldest and the trees are defi-
nitely larger than in the other two. All three are on virtually
identical fertilizer and pest control programs. Costs for these
groves and for those discussed below have been calculated on the
basis of standard fertilizer material costs given the author by
different concerns; standard dealer insecticide prices; and 3/4
cent per gallon for the application of sprays and 11/2 cents per
pound for the application of dusts. In addition, miscellaneous
charges include discing, chopping, and fertilizer distribution,
all at $1.25 per acre, and taxes at $12.00 per acre. No pruning,
irrigation, depreciation, etc., are included. Table 1 indicates
THE FLORIDA ENTOMOLOGIST
that the presence of snails neither reduced the cost of produc-
tion nor increased the yield in the groves considered.
TABLE 1.-A COMPARISON OF YIELD AND COST OF PRODUCTION IN THREE
GROVES WITH THE SAME FERTILIZER AND PEST CONTROL PROGRAMS.
Variety ...... Pineapple Parson Brown Mixed Pineapple
and Parson Brown
Snails ........ No No Yes
Boxes Cost Boxes Cost Boxes Cost
Year per per per per per per
Tree Box Tree Box Tree Box
1943 ........... 6.9 ...... 3.8 ...... 5.1
1944 ............ 5.9 ...... 3.6 ...... 5.2
1946 ............ 6.9 170 5.7 170 6.6 18s
1947 ....... 3.7 290 5.9 170 ,6.1 250
Average -. 5.9 230 4.8 170 5.8 211/20
Table 2 compares yield and cost data for two groves in Lake
County. Both are old groves and are situated within a few
miles of each other on the west side of the same lake. Both are
cared for by the same cooperative association and have similar
cultural and fertilizer practices. However, Grove A has no
snails and is on a complete spray program which included the
use of zinc, copper, DN, sulfur, and an oil emulsion while Grove
B has snails and is treated only with dusting sulfur. The groves
are both interplanted with various varieties and are essentially
comparable. However, in Grove A, only 22 per cent of the trees
are seedlings and grapefruit, while in Grove B, 37 per cent of
the trees fall into these two varieties. In spite of this differ-
ential, Grove A has averaged almost twice as much fruit per
acre as Grove B during the past three years. The fruit has
cost more to grow on a per box basis with the discrepancy caused
by the difference in spray and dust costs. It will be noted that
although spray costs averaged 11 cents more per box in Grove
A, miscellaneous charges averaged 4 cents per box less. This
latter figure represents fixed charges, but does not include de-
preciation, interest on investment, etc. The cost per box for
such fixed overhead is directly tied up with yield and decreases
TABLE 2.-A COMPARISON OF YIELLD AND COST DATA FOR Two SIMILAR GROVES.
Grove A No Snails Grove B Snails **
Year Boxes Boxes Boxes Boxes _
per per Cost per Box per per Cost per Box
Tree Acre ] Fert. Spray Misc. Total Tree Acre ] Fert. I Spray I Misc. Total
1945 ........ 4.0 338 21 140 60 411 3.1 225 250 20 9 360
1946 ........ 5.1 435 20 15 5 40 2.1 209 23 2 10 35
1947 ........ 5.3 452 12 11 4 27 3.6 260 12 2 8 22
Average .. 4.8 408 18 130 50 36 2.9 231 201 2S 90 310
Spray program includes use of DN, Zn, Cu, S, and oil.
** Pest control program consists of S dust only.
THE FLORIDA ENTOMOLOGIST
materially as yields increase. Although Grove B grows cheaper
fruit, its yield is materially reduced and fixed charges are of
greater significance in figuring costs.
Figures on the per cent of fruit sent to the cannery from each
of these two groves are available for comparison in only three
years. In 1943 and 1944, there was very little difference (See
Table 3), but the per cent was slightly in favor of the sprayed
grove. In 1947, when grades were considerably tighter, there
was a striking difference in favor of the grove without snails.
TABLE 3.-A COMPARISON OF THE PER CENT OF FRUIT SENT
TO THE CANNERY.
Variety 1943 1944 1947
SGrove A Grove B Grove A I Grove B Grove A Grove B
Parson Brown 11 0 12 31 11 -
Seedling ........ 20 34 49 41 53 81
Pineapple ...... 27 37 35 49 33 95
Valencia ........ 24 21 12 12 42 58
Average .. 21 23 27 33 43 76
No sweeping conclusions may be drawn from the yield and
cost data presented here. Tendencies are evident, but more in-
formation is needed. There is certainly no evidence here to
indicate that snail infested groves have yielded material benefits
to their owners. Apparently, the snails do no harm, and when
a grower does not wish to use a complete spray program, it is
possible that they are of some benefit. However, this conclusion
is not substantiated by any data collected by the author.
SUMMARY AND CONCLUSIONS
The activities of the snail, Drymaeus dormani, were studied
in citrus groves in Florida for more than two years. Eggs
were laid in June and July and hatched in July and August of
each year. The snails hibernate in crevices and cracks in the
trees during the winter months.
The snails feed on sooty mold and green algae on the trees.
No evidence was found to indicate that they feed on infesting
purple or Florida red scale populations. Scale infestations in
VOL. XXXII-No. 2
snail groves were similar to those found in other nearby groves
on similar pest control programs.
Cost and yield data for three groves on identical pest control
programs did not show increased yield or decreased costs due
to the presence of snails.
Cost and yield data from two similar groves, one with snails
on a sulfur dust program, and one without snails on a complete
spray program, showed that the grove with the complete spray
program produced almost twice as much fruit per acre for a
little more cost per box. Less fruit went to the cannery from
the sprayed grove.
No detrimental effects of snails were noted, but data col-
lected, so far, does not support the reported benefits attributed
to snail populations in the grove.
1. Binney, W. G. 1857. Notes on American land shells. No. 2. Proc.
of Acad. Nat. Sci. of Phil. 9: 188.
2. Binney, W. G. 1878. The terrestrial air breathing molluscs. Vol. V.
Bull. Mus. of Comp. Zool. 4: 1-10, 397.
3. Binney, W. G. 1885. A manual of American land shells. U. S. Nat'l
Mus. Bull. No. 28: 406-407.
4. Holloway, J. K., and T. R. Young, Jr. 1943. The influence of fungi-
cidal sprays on entomogenous fungi and purple scale in Florida.
J. Econ. Ent. 36: 453-457.
5. Norris, R. E. 1947. Some observations on the control of citrus pests
by tree snails in Lake County. Cit. Ind. 28 (10): 3, 10, 11.
6. Pilsbry, H. A. 1946. Land mollusca of North America. Acad. Nat.
Sci. of Phil. Mimeograph No. 3, Vol. II. Part I. 21-31, 37-39.
7. Sellards, E. H. 1906. The Manatee snail, Bulimulus dormani. Fla.
Agr. Exp. Sta. Press Bull. No. 59.
8. Simpson, C. T. 1893. Contributions to the mollusca of Florida. Proc.
Day. Acad. Sci. 5: 6-7.
9. Simpson, C. T. 1906. Notes. Nautilus 20: 24.
10. Smith, Maxwell. 1927. Non-marine mollusks of Volusia County,
Florida. Nautilus 41: 53.
11. Thompson, W. L. 1932. Insects of citrus. Fla. Agr. Exp. Sta. Ann.
12. Tryon, G. W. 1882. Structural and systematic conchology. Phila-
THE FLORIDA ENTOMOLOGIST
FIELD NOTES ON A COLOR VARIANT OF THE TWO-STRIPED
WALKINGSTICK, Anisomorpha buprestoides (Stoll)1
L. A. HETRICK
College of Agriculture, University of Florida
Large walkingsticks of a peculiar black and white coloration
were first observed by the writer late in 1947 at Juniper Springs,
Marion County, Florida. In October 1948 these same walking-
sticks were found to be very abundant near Salt Springs, Marion
County, Florida. Specimens were collected and submitted to
the United States National Museum for examination. Mr. C.
F. W. Muesebeck reported that the specimens had been examined
by Dr. A. B. Gurney who considered the insects to be a color
variation of Anisomorpha buprestoides (Stoll). The National
Museum specialists urged that cage studies of these insects be
made in order to definitely determine the correct taxonomic
In size and structure the black and white walkingsticks agree
with descriptions of Anisomorpha buprestoides (Stoll). Several
thousand pairs of the black and white form have been examined
by the writer as well as a large number of pairs of the more
typical brown form of Anisomorpha buprestoides. In the black
and white walkingsticks the anterior margins of the joints of
the antennae are consistently ringed with white. Also the
tergites of the thorax and abdomen are each consistently mar-
gined with a black band posteriorly. This brings about inter-
ruptions of the "two dorsal light stripes" from which the ap-
proved common name of Anisomorpha buprestoides is derived.
Comparable markings have not been found during examination
of many pairs of typical Anisomorpha buprestoides.
The area where large numbers of the black and white walk-
ingsticks have been found is a typical Florida scrub. Exces-
sively drained sandy soil characterizes such an area. Typical
plants of the scrub are the sand pine, Pinus clause Vasey,
Chapman oak, Quercus chapman Sarg., myrtle oak, Quercus
myrtifolia Willd., turkey oak, Quercus laevis Watt., tree lyonia,
Lyonia ferruginea Nutt., rosemary, Ceratiola ericoides Michx.,
and the palmetto, Sabal etonia Swingle.2
Apparently the oaks are the favored food plants of the black
and white walkingsticks. Feeding has also been observed on the
SOrder Orthoptera, Family Phasmidae.
2 Plant identifications were made by Miss Lillian Arnold of the Uni-
versity of Florida Agricultural Experiment Station.
VOL. XXXII-No. 2 75
foliage of rosemary and the tree lyonia. Fronds of the palmetto
are a frequent resting place for the insect but no indication of
feeding on this plant could be found. Occasionally the insects
have been collected from the trunks of the sand pine but it is
doubtful that the foliage of this tree would be acceptable as
Perhaps the most interesting observations made on the
black and white walkingsticks were those on the oviposition
habits of the insects. It is quite generally accepted that the
eggs of walkingsticks are dropped randomly and indescrimi-
nately upon the ground beneath the food plants of the adults.
Blatchley states that "the eggs are dropped loosely and singly
upon the ground by the mother". Comstock has written that
"the eggs are scattered on the ground beneath the plants upon
which the insects feed, the female, unlike most Orthoptera,
making no provision for their safety". In the black and white
form of Anisomorpha buprestoides many females were observed
to be digging small pits in the sandy soil, the eggs being dropped
into these pits and sand being scratched over them by the
females. Although no leg modifications for digging are appar-
ent, both the prothoracic legs and the mesothoracic legs are
used for this purpose. The mesothoracic legs are used exten-
Pair of walkingsticks over excavation in sandy soil, in which the eggs are
deposited. Photo by W. D. Sudia.
THE FLORIDA ENTOMOLOGIST
sively for covering up eggs that have been dropped into the
depressions. Apparently not more than eight or ten eggs are
laid into a hole; the female moves away and selects another
The male insect frequently remains attached to the female
during the process of oviposition. At first sight this appears
to be copulation but the male genitalia are attached to the ven-
tral portion of the segment anterior to the genital segment of
the female. Relative to Anisomorpha buprestoides, Littig has
stated that "in the act of copulation this organ (aedeagus of
the male) is typically inserted into the vulva, (8th sternite of
female) as many specimens were collected in this position.
Nevertheless, several males and females were collected with the
male organ inserted into a midventral opening posterior to the
7th female sternite which is possibly a primative gonopore".
Perhaps this is merely a means of aiding the diminutive male
in clinging to the body of the female.
Apparently Anisomorpha buprestoides is one member of the
Family Phasmidae that makes some provision to insure the
hatching of eggs by digging, them into the sandy soil. Perhaps
the covering of sand assures optimum humidity conditions for
the hatching of the eggs. The soil cover over the eggs may
1 "I -. ., : "
. Wo **' .',* ,
***/ *.. d' -i m
Female of Anisomorpha buprestoides excavating pit in sandy soil for
purposes of oviposition. Photo by W. D. Sudia.
VOL. XXXII-No. 2
serve to protect them from foraging birds or other predators.
It seems doubtful that eggs beneath the shallow soil cover would
survive winter fires that frequently burn over scrub areas but
this is worth some consideration.
Blatchley, W. S. 1920. Orthoptera of Northeastern North America.
Nature Publishing Company.
Comstock, J. H. 1920. An Introduction to Entomology. Comstock Pub-
Littig, K. S. 1942. External Anatomy of the Florida Walkingstick,
Anisomorpha buprestoides (Stoll). Fla. Ent. 25 (3): 34-41.
INSECTS FROM BURROWS OF PEROMYSCUS POLIONOTUS
The following records of commensal or parasitic insects
found in the burrows of the white-footed mice, Peromyscus
polionotus polionotus (Wagner) and P. polionotus rhoadsi
(Bangs) in Florida may be of interest in connection with the
ecology of those forms:
In burrows of P. polionotus polionotus:
Ctenophthalmus pseudagyrtes Baker (Det. J. Bequaert).
Jackson Co., Marianna, April 3, 1938, 1 specimen, C. C. Goff.
Recorded only as a parasite of the Pocket Gopher, Geomys
bursarius (Shaw), by Fox (U. S. D. A., Misc. Publ. 500,
In burrows of P. polionotus rhoadsi:
Arenivaga floridensis Caudell (Det. T. H. Hubbell).
Marion Co., Ocala National Forest, "Big Scrub" 11 mi. east
of Ocala, March 11, 1939, F. N. Young [1 juv. 9].
Ceuthophilus latibuli Scudder (All det. T. H. Hubbell).
Lake Co., Cassia, March 28, 1938, C. C. Goff [1 adult]; Emer-
alda, March 25, 1938, C. C. Goff [5 adults and juvs.];
Tavares, March 5, 1938, C. C. Goff [6 adults and juv.].
Marion Co., Ocala National Forest, "Big Scrub" 11 mi. east
of Ocala, March 11, 1939, F. N. Young [7 juvs.].
Orange Co., Zellwood, March 23, 1938, C. C. Goff [1 adult].
-Frank N. Young, Department of Biology,
University of Florida, Gainesville.
* i l