Everglades Experiment Station
Belle Glade, Florida
Mimeographed Report No. 12
RECENT ADVANCES IN THE CONTROL OF ANIMAL, PASTURE AND CORN PESTS
By Norman C. Hayslip
Recent Advances in the Control of Animal, Pasture Grass and Corn Pests
Norman C. Hayslip
I. CATTLE PESTS.--A number of new potent insecticides have been intro-
duced in recent years and rather extensive tests of these chemicals upon cattle for
the control of major cattle parasites are in progress in various cattle sections
throughout the United States and the world* A considerable amount of this research
has been developed by the U. S. Department of Agriculture and various State Experi-
ment Stations. The Everglades Experiment Station has no project on cattle pests at
tids time, but a limited number of trials and observations have been made,
A recent report by workers in the U.S.D.A. Bureau of Entomology and
Plant Quarantine (1) explains the present status of most of these new chemicals
on livestock, and a Florida press bulletin (2) describes the use of DDT on cattle
and in dairies. While this work is far from complete a digest of the findings to
date should be of value to everyone who has the responsibilities of cattle production.
The following review is taken from these two publications and other reports and ob-
servations in this area,
This insecticide has received more exhaustive study than any of the other
newer synthetic materials and has proved to be one of the most valuable insecticides
for the cattleman. There is some concern, however, over its use since recent studies
have revealed that DDT is stored in the animal tissues and eliminated in the milk
when forage crops containing DDT are fed to animals.
Use on cattle.--Wettable powders are most generally recommended for use on
cattle. T7E3s form ofDDT is available in most areas as a 50 percent DDT powder
which may be mixed with water. DDT emulsion has been used with equal success, but
is not generally recommended because certain formulations have produced harmful
effects on cattle. Since the wettable powder offers greater safety and is very
effective in its control this form of DDT is recommended.
There has been considerable confusion in the recommendations which vary
from .25 percent to 2.5 percent DDT spray at a rate of 1 pint to 1 gallon per animal.
In order to clarify this point it may be stated that it is not the amount of DDT
which passes through the spray nozzle that is important, but the amount applied upon
the animal and the coverage obtained. The important point should be to determine how
much of the spray is lost by falling upon the ground or drifting away in the air.
If one gallon of spray must pass through the spray nozzles in order to obtain
thorough, even coverage of an average mature animal and half of this spray is lost,
then about one gallon of a 0.5 percent DDT spray per animal would be best. On the
other hand, if a small efficient power sprayer should require only one quart of
spray to obtain a thorough, even coverage and the amount of loss was about 10 per-
cent, a 1.5 percent DDT spray at the rate of one quart per animal would probably be
Generally speaking, a large power sprayer using about 2 quarts per mature
animal of a 1 percent DDT spray should prove adequate for flies and mosquitoes. From
2 4 quarts of this material may be required for each mature animal for control of
cattle lice and ticks. If a small power sprayer which will give good coverage at 1
quart of spray per animal is used a 1 2 percent spray should be used.
Horn flies.--This pest is very susceptible to DDT. The Everglades Station
has obtainedTxce1lent control using DDT at the rate of 1 pound technical DDT per
450 animals by mixing wettable DDT in water and applying to the heads and backs of
the animals with a knapsack sprayer. A more thorough treatment is recommended, how-
ever if a longer period of protection is desired. Two quarts per animal of a 1 per-
cent spray applied with a power sprayer should give 3 4 weeks protection.
Stable flies.-The stable fly problem has not been so serious in the
Everglades 'area sii DDT came into general use on vegetables and pastures. This
Station has found that treatment of town lot animals with DDT does not give satis-
factory control, but in treating dairy barns and other resting places good control
has resulted. The most effective control may probably be in the treatment of
breeding areas such as straw, seaweed, vegetable refuse, etc.
Mosquitoes.--Where airplane dusting or spraying service is available, area
treatment with DDT is very effective and offers protection for at least one week.
Mosquitoes feeding upon animals treated with DDT will die for several days after
spraying and this should help relieve a mosquito problem. Treatment of barns also
is effective in reducing the mosquito population.
Horse flies and deer flies.--Observations indicate that applications of
DDT to lives- ck 'F- no3eNe'tivein controlling these pests. The effect of large
area treatment by plane is not known.
Cattle lice,--DDT is very effective against these pests. The Bureau of
Entomology reportsfT at complete eradication of lice is possible vi th onr application
if the coverage is thorough and complete. Dipping is more likely to result in
eradication than is spraying, but excellent control is obtained either way. Use 2 -
4 quarts of 0.5 percent DDT per mature animal if sprayed and the same concentration
is used for dipping. A second treatment about three weeks following the first wivl
probably eliminate lice from the herd.
Ticks.--Ticks are not easily controlled by insecticides, but DDT is one of
the most sat-sfactory materials for the control of the lone star tick, cattle fever
tick and gulf coast tick, DDT is reported to be ineffective against engorged ticks,
but highly effective to the nymphs and unengorged adults.
Use in dairy barns.-Very good control of house flies, stable flies,
mosquitoesa-nd roaches can be obtained in dairies and around stables if all walls
and ceilings are sprayed with DDT. A 2.5 percent spray using the wettable powder,
emulsion or oil based DDT should be applied freely to the buildings. Wet the svr-
face thoroughly but do not allow any run-off. Usually about one gallon of spray per
1000 sq. ft. is sufficient. A long period of protection results from a treatment of
This material has been used in considerable quantities in Florida for the
control of several vegetable insects. A report by Bureau of Entomology and Plant
Quaratine workers (1) has summarized the status of this insecticide. Benzene hex-
achloride has shown greater toxicity to many livestock pests than any other new
material. Its residual action, however, is shorter than DDT and its odor further
limits its use. DDT has proven superior in horn fly and house fly control because
it is longer lasting. Benzene hexachloride shows promise in deer fly and stable fly
control but the effect is not long lasting. Recent work indicates that this pcison
is superior to DDT in controlling lice on cattle. Against the lone star tick it gavo
a better kill of the ticks than did DDT, but DDT was superior in preventing rein.
festation. A combination of the two materials offers much promise in tick control
This insecticide has received considerable testing at the Everglades
Station against vegetable insects and has shown definite promise in this field.
Against livestock parasites it has not been tested as extensively as has benzene
hexachloride. Cooperative tests between the Bureau of Entomology and Plant Quarantine
and the National Livestock Loss Prevention Board and State Agricultural Experiment
Station of Kansas and Missouri indicate that it is generally less effective than DDT.
Against lice on cattle it may be equal to DDT, and against the lone star tick and
winter tick it may prove superior to DDT. Preliminary investigations using this
material for preventing reinfestation of susceptible animals to screwworm attack are
promising. Tests against cattle grub, lice, deer flies and house flies indicate
that this insecticide is not promising.
Comparative tests show this material inferior to DDT against horn flies.
Against house flies it is less persistent than DDT, but highly effective. It is
promising for the control of lice on cattle. It is comparable to DDT against the
lone star tick. Chlordane is not effective in protecting animals from horse flies.
Substitutes for DDT
Since DDT is taken up and accumulated in the tissues and milk of animals
more interest is being directed at substitutes for DDT, Methoxy DDT and DDD are re-
ported to be less toxic to warm blooded animals and are receiving attention as
possible substitutes. They have been found generally less effective than DDT, but
in some cases they seem promising. A report of preliminary tests in South Carolina
suggests that methoxy DDT and combinations of this insecticide with Benzene hexa-
chloride may give relief against horse flies and deer flies.
(1) BISHOPP, F. C. and KNIPLING, E. F. Industrial and Engineering Chemistry,
Vol. 40, No. 4, Page 713, April 1948.
(2) TISSOT, A. N. Fla. Agr. Expt. Sta. Press Bulletin 630, January 1947.
II. PASTURE GRASS.--The most severe insect pest attacking pastures in
South Florida has been armnworms. TJhile several species of worms seem t9 be in-
volved, the fall arnyworm is the most prevalent and destructive. At times cutworms
(closely related to arnyworms) become abundant enough to cause heavy damage to
grasses. Preliminary trials at this Station last fall indicate that 5 percent DDT
or 5 percent DDD (Rhothane) should give good control of these pests when applied at
20 30 pounds per acre. Many pastures have been dusted with 5 percent DDT wlth
airplanes and the control obtained has usually been satisfactory. Since cattle co n-
sume a substantial quantity of DDT in grazing it is recommended that they be removed
from treated pastures for about two weeks after treatment. There have been no re-
ports of acute poisoning to cattle left on the pasture, but the fact that substantLel
q-antities of DDT have been found in the animal tissues and milk makes such a pre-
cautionary measure advisable.
Leafhoppers are found in large numbers on pastures in some areas. The
total effect of these sucking insects is not known, but their importance is usually
under-rated. It is easy to see the damage caused by leafhoppers on beans, but the
damage in grass is not so apparent. DDT dust is very effective against most leaf-
hoppers and should be used where these pests are severe.
III CORN PESTS.-Insects constitute one of the most serious problems in
corn production. This past season has demonstrated the destructive possibilities of
cutworms, arnyworms, earworms and wireworns. Entire plantings of corn are sometimes
destroyed by cutworms and arnyworms. The fall arnyrvorm in the buds of corn often
causes severe injury in killing the buds of young corn and in cutting and eating
the tassels in addition to their heavy feeding upon the ears of corn. This pest
acting as a budworm probably reduces the yield of corn even where the stand is not
destroyed. The corn earworm is not as destructive on field corn as on sweet corn,
but this pest takes its toll in total yield of good quality corn. Corn culture in-
creases the wireworm problem since the adult click beetles are attracted to growing
corn and deposit their eggs in these areas*
All of the above mentioned insects can be controlled. However, to control
them at a cost which can be justified for field corn presents a special problem.
As long as the market price of corn is high, chemical control can probably be used
and the following summary and suggestions for control are made on that basis.
The most critical period in cutworm damage is from the time the corn is
planted until it is about 12 inches tall. If a good stand of corn remains by this
time the chance of maintaining this stand is very good. It is sometimes difficult
to understand how a complete field of corn can be totally destroyed so rapidly by
cutworms and armyworms. A better understanding of what happens in these cases shoul-
aid in preventing such heavy losses. In many cases soil containing a heavy crop of'
weeds and grass will be plowed, disced and planted to corn in rapid succession. Atf
the time the corn is planted there may be thousands of cutworms in the soil which
had been feeding upon the weeds and grasses. With all their food source destroyed
these worms begin feeding upon the germinating corn as soon as it appears above tho
ground. Early symptoms of their presence may not look so severe with a tiny plant
cut off here and there along a row. However, the amount of food for these worms is
very limited and as soon as they eat one tiny plant they migrate to another and soon
join other worms and feed along with them. As these worms migrate they join more
and more worms and soon they assume arnyworm tactics of feeding day and night because
they are competing with many more worms and never get enough food. In a large corn
field early evidence of these "arnyworm" waves appears in the form of rather small
areas where there are no corn plants. From this stage to complete destruction of
the entire field is only a few days and rapid treatment is necessary to save the crop,
If the following steps are taken this severe damage from cutworms can be
avoided. (1) The land should be prepared well in advance of planting in order to
reduce the cutworm population. (2) If cutworms are known to be present a poisoned
wheat bran bait may be applied before planting. Four pounds of Paris green or 12
pounds of undiluted cryolite may be mixed with 100 pounds of wheat bran and broad-
cast in the late afternoon. Airplanes may be used in applying these baits or they
may be broadcast with ground equipment or by hand. A 5 percent DDT dust at 40 50
pounds per acre also has been reported to give good control of cutworms.
(3) Inspect the entire planting every 3 4 days for signs of cutworms until the
corn becomes well established. If cutworms are localized use spot treatments of
poisoned baits, sprays or dusts. If the acreage is large, mount a tractor and ride
the fields in order that the entire area can be inspected. If a light infestation
is found scattered over the planted area, treatment may be delayed until time to
spray for budworms. However, observe this light infestation closely with dally
inspection because it may be more serious than suspected. If a rather heavy in-
festation is found scattered over the entire planted area, treat at once with
(A) poisoned bait or, (B) a spray consisting of 1 quart DDT emulsion per 103 gale
water, or (C) 5 percent DDT dust. If spraying is too slow, apply poisoned bait
or dust by airplane. Paris green or cryolite-wheat bran bait may cause some injury
to corn when it comes in contact with the plant, but baits applied at about 20 pounds
per acre should cause no serious damage.
The fall arMyworm appears to be the most serious species of armyworm
attacking corn in South Florida. This pest is most always present as budworm in
corn plantings and is especially destructive in the spring. In addition to the budw.
worm type of feeding this pest often migrates to corn from adjacent fields, or from
weeds and grass which have been killed by cultivation. In this latter case the pests
assume real armyworm habits in completely destroying the corn as they migrate by
thousands through the field. Most often an invasion of this type comes from border i
fields of weeds and grass, but at times arnyworms become established on the weedc
and grass in the corn field. When the weeds are destroyed the worms migrate to the
corn and cause heavy losses. Since there are two distinct types of damage caused
by armnworms requiring slightly different treatment they will be discussed separately,
The "budworm" in corn is usually the fall armyworm or the corn earworm.
In South Florida the fall armyworm is most prevalent in the buds of corn. The moth
deposits egg masses on the corn leaves. These eggs hatch into tiny worms which
feed upon the leaf for a short period and then migrate into the bud. The worm
remains in the bud until it is mature. It then goes into the ground to form the
pupal or resting stage. The moth emerges from this pupa. In the spring the moths
deposit eggs on the corn soon after germination and continue to infest the corn until
it reaches maturity. Because of this continuous reinfestation weekly spray or dusu
treatments may be required in order to keep the corn free of worms. It is readily
apparent that the expense of weekly spraying may be excessive for field corn, so
the important point should be the proper timing of treatments and the number of
treatments required to make a crop of corn. A study of this type is in progress at
this Station and more information will be available at the completion of this ex-
periment when yields of corn will have been taken fiom the various treatments. A
summary of this study to date is included to show the effect of the various treatment
(time and number) combinations.
EFFECT FP TIITNG AND NUMBER OF TREATMENTS 1ITH TWETTABLE DDT SPRAY
FOR THE CONTROL OF CORN BUDtl'RS1
Height cf corn and p.t e- of ScC ay a :i'.atior-.
ment Cor0n Corn of buds
No 6" high 10" high 36'9 high inieted
S(April 10) (April 21) (May 1) ITa/
7 X 33
8 Check 98
N _r I I : : "' l l I I I l i
1 All treatments except No. 8 received
wettable DDT per 100 gal, water appl:
acre with a power sprayer using 3 no
2 Corn planted March 25.
3 "X" indicates treatment was applied.
a spray of 2 pounds of .0 percent
ied at the rate of 100 gal. per
zzles per row. Treatment No. 8 was
A comparative study of several of the newer promising insecticides was
conducted in cooperation with the Agronomist. The results of this experiment
are recorded in the following table.
EFFECT OF INSECTICIDE TREATMENTS ON THE CONTROL OF FALL ARIT7ORMS IN THE BUDS OF CORN
Percent of Buds Infested
Material Amount 7Day Aftefr "ays After
1. 50 percent wettable DDT 2 lb. per 100 Gal. 29.7 4.5
2. 50 percent wettable methoxy DDT 2 lb. per 100 Gal. 40.2 9.4
3. 50 percent wettable DDD 2 lb. per 100 Gal. 32.7 9,6
4. 15 percent wettable parathion 1 lb. per 100 Gal. 36.3 9.7
5. HCH wettable-6 percent gamma
isomer 4 lb. per 100 Gal, 33.6 14.
6. 25 percent chlorinated camphene
wettable 4 lb. per 100 Gal. 28.5 7*3
7. 50 percent wettable chlordane 2 lb. per 100 Gal. 22.9 7.5
8. 15 percent wettable parathion ) lb. per 100 Gal. 39,7 11.3
9. DDT-wheat bran bait 5 percent DDT 35.5 6.6
10. Chlordane-wheat bran bait 5 percent chlordane 19.0 2.8
11. Parathion-wheat bran bait 1.5 percent parathion 13,4 0,0
12. Check, untreated 95,3 85.2
Sprays were applied with a three nozzle boom at 200 pounds pressure. Baits
were applied by hand, throwing a small pinch in each whorl. Corn was first
treated when about 16 inches tall, and almost 100 percent of the buds were
infested with fall arnyworms at this time.
It will be noted that most of the treatments gave good control. Since DDT:
DDD and chlorinated camphene wettable powders are very effective and not too expensive
one of these insecticides should be used if the corn is to be sprayed. Previous ex-
periments have indicated that spraying is superior to dusting for budworm control.
The good control obtained with poisoned baits warranted further study, and additional
trials were made. The results of these latter trials are summarized in the following
EFFECT OF POISONED BAIT TREATInITS ON THE CONTROL OF THE FALL
ARMUrORM IN THE BUDS OF CORN
Percent of Buds Infested
Block A Block B
Treatment :Just rior 4 Days Just Prior 4 Days
To After To After
sTreatment Treatment Treatment Treatment
1-Parathion-1 percent in wheat bran 100.0 6.3 72.5 .*8
2-Parathion-1 percent in wheat bran 100.0 9.1 79.7 13.3
3-Parathion-4 percent in wheat bran 93.6 6.3 68.7 7.7
I-Parathion-1/8 percent in wheat bran 96.8 9,5 85.1 8.8
Chlorinated camphene-5 percent in 902 13.1 88.0 2.0
6-Chlordane 5 percent in wheat bran 96.1 17.6 88.9 7.9
7-Chlordane 5 percent (Commercial mix) 90.6 28.1 90.4 18.1
8-HCH 0.36 gamma isomer in wheat bran 91.2 35.3 71.0 20.3
9-Check, not treated 91.5 94.9 89.7 94.8
It will be noted in the above table that 1/8 percent parathion was equal
to 1 percent parathion; that the commercial chlordane bait was inferior to the
wheat bran mix and that the benzene hexachloride bait was inferior to all treatments
except possibly the commercial chlordane bait. The sharp reduction in budworms
following one bait application is encouraging and may prove useful in budworm con-
trol if satisfactory methods of application are developed. Vhile there is some
evidence of good control with poisoned baits applied by airplane for budworm con-
trol this point has not been investigated. If growers have corn too large to treat
with ground equipment they would do well to compare one of these poisoned baits with
a dust application from airplanes. This Station contemplates work along these lines
Armyworms migrating into corn plantings from other areas must be treated
at once. If they have migrated from an adjoining field, spot treatments may place
them under control. If they are general over the planting the entire crop must be
treated. A 5 percent DDT dust applied at 25 35 pounds per acre should give ade-
quate control of these pests.
This moth deposits eggs on the silks. The eggs hatch and the small worms
migrate into the tips of the ears and feed upon the corn. While it is necessary
to control this pest in corn for roasting ears it is doubtful that treatment on fie3d
corn would be economically feasible.
These pests constitute a real problem in corn production. The adults
(click beetles) are in flight in the spring and summer at which time they deposit
eggs on the ground* Wireworm increases are noted where ccrn or grass and weeds
are growing during this flight period Corn attracts the adults and mary nay be
found resting in the spring corn. Wireworm larvae are often abundant enough bo
cause a severe reduction in the stand of corner Symptoms indicating the presence
of these pests are wilted plants. If these wilted plants are pulled up and ex-
amined the wireworms are found either in the corn plant or in the soil near:-by
Preliminary trials at this Station indicate that chlordane and parathion may give
satisfactory control of wireworms. When chlordane was mixed vith fertilizerr and
applied immediately good control'was obtained. Further studies are necessary be-
fore recommendations can be made.