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Group Title: Circular / Florida Cooperative Extension Service ; no. 425
Title: External parasite control on horses
CITATION PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00067160/00001
 Material Information
Title: External parasite control on horses
Series Title: Circular Florida Cooperative Extension Service
Physical Description: 7 p. : ill. ; 28 cm.
Language: English
Creator: Koehler, Philip Gene, 1947-
Butler, Jerry F
Publisher: Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville
Publication Date: 1980?
 Subjects
Subject: Parasites -- Horses   ( lcsh )
Horses -- Diseases   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: Philip G. Koehler and Jerry F. Butler.
General Note: Cover title.
Funding: Circular (Florida Cooperative Extension Service);
 Record Information
Bibliographic ID: UF00067160
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 08895982

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HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida






Circular 425


ENTOMOLOGY


EXTERNAL
PARASITE
CONTROL
ON
HORSES


PHILIP G. KOEHLER
JERRY F. BUTLER



Florida Cooperative Extension Service
Institute of Food and Agricultural Sciences
University of Florida, Gainesville
John T. Woeste, Dean for Extension


If










EXTERNAL PARASITE CONTROL ON HORSES


Arthropod parasites of horses include internal
bots which infest the digestive tract, mites which
burrow in the skin and feed on the skin surface,
ticks which infest the ears as well as the skin, lice
which either suck blood or feed on skin, blood
sucking flies and mosquitoes which range in size
from biting gnats just observable with the naked
eye to the large black horse flies which are almost
one inch long. Non-biting flies such as house flies
and face flies are also important in producing fly
worry, irritation and disease transmission.
These parasitic habits are complicated by dam-
age caused by disease transmission and severe
host reactions caused by an immune response.
Signs of damage usually show up as weakness,
emaciation, anemia, rough hair coat, stunted
growth, tail and mane rubbing, lesions and di-
sease transmission. Extreme populations or trans-
mission of disease may lead to death of the host.

HORSE BOTS
Horse bots are bot fly larvae which are internal
parasites of horses. The horse bot larvae develop
in the stomach of horses causing symptoms
ranging from stomach ulcers, esophageal paral-
ysis to occlusion of the digestive tract.

Biology
The adult bot fly is a bee-like fly about 1/2 to
8/4 inch in length. Bot flies are covered with black
and yellow hairs and do not feed as adults. In
Florida two species of adult bot flies may be ac-
tive throughout the year, although they are more
abundant from late spring to early winter (Aug.-
Sept.).
Female bot flies lay from 150 to 1,000 yellowish
eggs. The eggs are firmly glued to the hairs of the
forelegs, belly, flanks, shoulders and other parts
of the body of the horse. While the fly's egg
laying does not cause the horse pain, the horse
often is bothered by the presence of the fly.
Egg laying principally occurs on the inside
knees of the animal where the horse can easily
reach the eggs with its tongue. The eggs are
ready to hatch 7 to 10 days after oviposition, and
will hatch only if the horse licks or bites the area
where they have been glued. It is believed that
the sudden increase in temperature from the
tongue stimulates the young larvae to hatch.


Once inside the horse's mouth, the larvae bur-
row into the mucous linings of the mouth and
tongue and remain there for 3 to 4 weeks. Dam-
age to the mouth membranes is often seen during
this stage. From the mouth, the larvae pass to the
stomach and intestine where the second and third
instar larvae remain attached but may change lo-
cation. They remain in these areas until the fol-
lowing summer.
When fully mature, the third stage larvae de-
tach from the stomach and pass through the in-
testines and are passed in the droppings. They
migrate out of the droppings and burrow under
the surface of the soil. Here the pupae remain for
1 to 2 months. The fly emerges throughout the
summer and fall.
The individual fly does not feed but starts its
egg laying cycle, which lasts for about two weeks,
then it dies. Cold weather and frost usually kill
off the remaining flies in the fall of thel year and
signal the end of the egg laying season. Only one
generation is completed per year.
In south Florida, adult bot flies have been
found to be active year-round. In central and
north Florida adults are found from spring to
early winter. Highest populations of adults are
recorded from August through September.
Larval populations sampled in horses in Octo-
ber and November ranged from 1 to 184 larvae
per stomach in central and north Florida.

Symptoms
A few bots will cause little damage; however,
increasing populations cause gastrointestinal dis-
turbances. Infestations can produce symptoms
varying from mild to severe. Symptoms include
irritation of stomach membranes, ulceration of
stomach, peritonitis, perforated ulcers, colic,
mechanical blockage of stomach resulting in
stomach rupture, esophageal paralysis, and squa-
mal cell tumors.
In addition to the previous pathogenicity the
first stage larvae migrating in the tongue and
gums have been shown to cause pus pockets in
the mouth. The larvae developing in the stomach
have also been shown to cause severe anemia.
Cases have also been reported of horse bots in
man. The first stage larvae have been found mi-
grating in the skin of man cutaneouss myiasis)


Philip G. Koehler and Jerry F. Butler are Assistant Professor-Extension Entomologist and Associate Professor, respectively,' Department of
Entomology and Nematology, Institute of Food and Agricultural Sciences.









and horse bots have also been reported in the
stomach of man and pig.

Control
Effective control of horse bots requires
breaking the life cycle of the fly. Insecticides (see
Table 1) are labeled for external treatment in a
warm water wash after eggs have been laid but
before they hatch. For external insecticide treat-
ment, a warm water wash (1100-1200F) should
be rubbed or sponged on areas infested with eggs.
The larvae will hatch and die from contact with
the insecticide. Treatments should be applied
weekly during peak oviposition periods (August-
September). During the wash, care should be
taken to protect hands from insecticide and lar-
vae with synthetic rubber gloves. Grooming may
aid in removal of eggs but effectiveness of control
is questionable.
For internal treatment of horse bots, consult
a veterinarian. Insecticides (see Table 2) are
labeled as liquids, bolus, and feed additives for
horse bot control. Internal medications will usu-
ally control second stage but may not control
third stage larvae. Most effective treatments
should be applied one month after first sighting
of eggs to control second stage larvae. Materials
which control both second and third stage larvae
should be applied in the fall of the year. Carbon
disulfide is effective but may cause gastritis with
sloughing of stomach mucosa. Dichlorvos is effec-
tive but may not be readily eaten as a feed addi-
tive.


HORSE AND DEER FLIES
Horse flies and deer flies are insects that are
usually daytime feeders and are vicious biters
and strong fliers. As with mosquitoes only the fe-
males bite. Their attacks often account for
lowered weight gains and reduction in condition.
Because of their painful bites and frequent at-
tacks, horse flies produce frenzied behavior in
their hosts, sometimes causing them to run long
distances in an effort to escape. Horse flies intro-
duce an anticoagulant into the wound when they
bite which causes blood to ooze for up to eight
hours. These wounds are excellent sites for sec-
ondary invasion of screwworm and also cause
much blood loss. Being intermittent feeders, they
are known mechanical transmitters of diseases
such as anthrax, tularemia, anaplasmosis, and
equine infectious anemia (EIA).


Most species of horse and deer flies are aquatic
or semi-aquatic in the immature stages, but some
develop in moist earth, leaf mold or rotting logs.
Generally the eggs are deposited in layers on
vegetation, objects over water or moist areas
favorable to larval development.
Eggs hatch in 5 to 7 days and the larvae fall
to the surface of the water or moist areas where
they begin to feed on organic matter. Many
species prey upon insect larvae, crustacea, snails
and earthworms.
When the larvae are ready to pupate, they move
into drier earth, usually an inch or two below the
soil surface. The pupal stage lasts 2 to 3 weeks,
after which the adults emerge. The life cycle
varies considerably within the species, requiring
anywhere from 70 days to 2 years.
Control of these flies is difficult with no treat-
ment of the larvae possible. Repellents will give
relief for up to 24 hours when applied to the ani-
mal.



OTHER BITING FLIES
Mosquitoes
Mosquitoes are small, two-winged flies with
piercing sucking mouthparts. Females of most
species suck blood, males do not. Mosquitoes at-
tack all kinds of warm-blooded animals, domestic
and wild. Florida has many species recorded as
economic pests on livestock.
Although habits of different species vary
greatly, all require water for the larvae. Female
mosquitoes lay their eggs on water or in places
that later become flooded. Egg hatch varies with
the species. Larvae wigglerss) hatch from the
eggs and feed on organic matter in the water.
Pupation takes place in the water. The adult
mosquito emerges and is ready to feed in a short
time.
Damage caused by mosquitoes include pain
from the bites, unthriftiness, death by suffocation
and heavy blood loss. Mosquitoes also vector such
diseases as encephalomyelitis (WEE, EEE,
VEE) and are suspect for any of the mechani-
cally transmitted diseases.
If mosquitoes are a serious problem to horses,
control measures should be implemented. The
most effective control method available is source
reduction by removing or draining mosquito
breeding sites. Daily fogging or aerosoling for
adult mosquitoes may provide temporary relief
but is only a temporary control measure.









Stable Flies
The stable fly, or dog fly, is similar to the house
fly in size and color, but the bayonet-like mouth-
parts of the stable fly differentiate it from the
house fly. Unlike the flies already discussed, both
sexes of the stable fly are vicious biters. They are
strong fliers and range many miles from the
breeding sites.
Stable flies cause irritation and weakness in
animals and account for much blood loss in severe
cases. Bite wounds also can serve as sites for
secondary infection. These flies are easily inter-
rupted in feeding and are mechanical transmit-
ters of anthrax, equine infectious anemia (swamp
fever) anaplasmosis and stomach worms, Habro-
nema.
Stable flies breed in soggy hay, grain or feed,
piles of moist fermenting weed or grass cuttings,
spilled green chop, peanut litter, seaweed deposits
along beaches and sometimes in manure well
mixed with hay. The female, when depositing
eggs, will often crawl into loose material, placing
the eggs in little inner pockets.
Each female may lay a total of 500 to 600 eggs
in four separate layings. Eggs hatch in 2 to 5
days and the newly hatched larvae bury them-
selves, begin to feed, and mature in 14 to 26 days.
While the average life cycle is 28 days, this period
will vary from 22 to 58 days, depending on
weather conditions.
Adult flies are capable of flying up to 80 miles
from their breeding site. If more than 5 to 10
flies are present per animal extensive fly rearing
is present in the area.
Stable fly control is most successfully ap-
proached with cultural control measures. Since
the larvae require a moist breeding media, it is
essential that the breeding source be found and
dispersed to allow drying. Animal treatments are
limited to fogging or mist applications of insecti-
cide and the use of repellents which may last for
2 to 3 days.

Sand Flies and Biting Midges
("Punkies, No-See-Ums")
Other blood sucking flies that are often prob-
lems to cattle and horses include many species of
Phlebotomus flies, sand flies (Culicoides and Lep-
toconops) and biting midges punkieses, no-see-
ums"). All of these flies are associated with wet
or aquatic habitats. Because the areas are so
often associated with water or swampy conditions
these pests become a problem which is difficult,


if not impossible to control. Several species of
sand flies and biting midges are of economic im-
portance on livestock.
The life cycles and habits of midges affecting
livestock is poorly known. The sand flies are con-
sidered the most important livestock pests of this
group. One species is a known vector of blue
tongue virus in sheep and cattle. Damage is usu-
ally seen in skin reactions and lesion formation.
Horses may lose the hair in the infected areas
because of fly feeding. No effective control meas-
ures are available for these flies.
The black flies are small flies and are not as
common in Flprida as in other regions. Eighteen
species are reported for Florida. Four species
feed on cattle and horses. Damage from black flies
feeding includes animal losses along the river
basins. Death usually occurs as a consequence of
an acute toxemia caused by vast number of bites
or as a result of anaphylactic shock. Both weak-
ness from heavy blood loss and suffocation by in-
halation may also attribute to animal loss. Di-
seases are vectored by black flies in other regions.
Black flies are small, dark, stout-bodied flies
with a hump-backed appearance. The adult fe-
males suck blood mainly during daylight hours
and are not host specific. The black fly is a poten-
tial disease vector in Florida. It hovers about the
eyes, ears and nostrils of animals, often alighting
and puncturing the skin with an irritating bite.
Large numbers of bites may cause weakness from
blood loss, anaphylactic shock or death.
The black fly life cycle begins with eggs being
deposited on logs, rocks or solid surfaces in
swiftly flowing streams. Larvae attach themselves
to rocks or vegetation with a posterior sucker.
The length of the larvae period is quite variable
depending on the species and the larval environ-
ment. The adults which emerge after pupation are
strong fliers and may fly 7 to 10 miles from their
breeding sites.


Horn flies
Horn flies often attack horses which are pas-
tured near cattle. These blood feeding flies do not
develop in horse manure but migrate to horses
from cattle pastures. They do feed on horses and
may build to more than 65 flies per animal. In
Florida they are common and persistent blood
feeders causing damage by irritating the animal.
The life cycle of the horn fly takes place only
in fresh cow manure. Eggs hatch in about 18
hours and the larvae feed in the individual pad-









dies, passing through three instars in 3 to 5 days.
The pupal stage lasts 3 to 5 days and the adults
which emerge have a preoviposition of three days.
Mating takes place on the host with females lay-
ing about 200 eggs in their lifetime.
These flies apparently migrate extensively and
will go to and stay on horses.
Control of horn flies on horses can be achieved
with any of the residual treatments applied for
insect control on horses.

NON-BITING FLIES
The common house fly is of concern to both
livestock producers and people who live around
farmstead areas. The animal industry cannot
raise animals without producing manure which is
the house fly's preferred breeding site. The com-
mon house fly is found both inside stables and on
the animals themselves. If the farm is located
close to any public housing areas, house flies are
an immediate concern to the animal industry be-
cause they can be mechanical vectors of human
disease.
House fly damage to horses is from annoyance
caused by persistent feeding on the muzzle, eyes
and open wounds. Animals become nervous, rest-
less, and reduce food intake. House flies are also
intermediate hosts for stomach worms (Habro-
nema), diseases and parasites of horses. It has
also been shown that the house fly is capable of
transmitting diseases such as bovine mastitis and
pink eye. In addition house flies are known to be
contaminated with more than 100 species of
pathogenic organisms.
The house fly has complete metamorphosis,
going through the egg, larva, pupa and adult
stages. The adult female searches for a suitable
larval medium to lay eggs. Poultry and livestock
manure, organic refuse (plant and animal),
waste, garbage and other filth is normally se-
lected for oviposition. The adult female lays 75
to 150 oval, white eggs that hatch in 8 to 12
hours. The larval stage is composed of three lar-
val stages lasting 3 days to 3 weeks. The pupal
stage lasts 4 to 5 days after which the adult
emerges. Thus in a minimum of 10 days under
optimum conditions a house fly can develop from
egg to adult.
Control of house flies is a continuing operation,
in which sanitation and moisture control is the
most important step. Manure should be removed
and disposed of every 4 to 5 days in summer and
less frequently in cool weather. The most ideal
method of disposing of manure is to spread it on


land where it can serve as fertilizer.
If flies continue to be a problem after sanita-
tion and moisture control practices have been im-
plemented it may be nessary to apply chemical
control methods. Chemical controls may be ap-
plied as larvicides, baits, residual sprays, and
space sprays.
Larvicides are chemicals applied to manure to
kill house fly maggots. They are effective in re-
ducing house fly breeding when applied thor-
oughly.
Baits are composed of an attractant material
such as sugar and an insecticide. The flies are at-
tracted to the bait and killed by the insecticide.
Dry baits should be applied to hard dry surfaces
so they will not dissolve and become ineffective.
Residual sprays are normally insecticides which
are applied to surfaces flies frequently contact.
These surfaces can be rafters, beams, structures
or any place flies tend to rest. Space sprays are
effective in quickly knocking down flies which are
prevalent in areas. Since there is no residual ef-
fect, insecticides applied in this manner must be
applied frequently.
The face fly is not presently in Florida. It is
present in a corner of Georgia and Alabama and
could migrate into Florida if it is able to adjust
to our conditions. Its oviposition is similar to the
horn fly. Its feeding habits on the host are similar
to the house fly except it congregates at the eyes.
The face fly avoids shade preferring the open
sunlight which is the opposite of the house fly
which it closely resembles: It causes severe irri-
tation on the face and eyes and is very difficult to
control.
Eye gnats are very common small flies seen
around the faces of horses throughout the sum-
mer months. The larvae develop in organic mat-
ter in the soil. No effective control methods are
available for this pest.
At least 60 species of blow flies have been re-
ported for North America. The primary screw-
worm fly is a true parasite; other blow flies and
their larvae feed mainly on cadavers or they may
invade necrotic wounds.
The blow flies are most numerous in the spring
and fall. In general eggs are laid in open wounds
and putrid organic debris. The larvae develop
feeding on dead tissue or living tissue. As the
larvae mature they fall out and pupate in the
ground. About 17 days are required from egg to
adult.
Adults may lay as many as 1,000 eggs in a
lifetime in batches of 100 to 250. The primary









screwworm has been eradicated by the 'sterile
male method in the Southeast but is still present
in the Southwest and is always a potential threat.
Control is best achieved by proper care of in-
jured animals and proper disposal of putrid or-
ganic debris.

HORSE LICE: BITING AND SUCKING
Two biting lice and one sucking louse infest
horses and mules. Heavy infestations usually are
seen in the winter and may cause anemia, un-
thriftiness, loss of condition, stunting of growth,
uneasiness, loss of hair and even sores, wounds
and scabs from rubbing of the irritations.
Lice are permanent parasites of their hosts,
spending the entire life cycle on the host. Most
species live only a short time off the animal and
are not found on other species of animals. The
horse sucking louse, will only live for 2 to 3 days
off the host. The life cycle for this louse takes
4 to 5 weeks for completion from egg to egg with
5 to 14 days required for egg hatch. Egg produc-
tion for different species varies from 50 to 100
eggs 4 to 5 weeks. It is seen in damaging numbers
in the winter and may be found anywhere on the
body.
Biting lice feed on the skin and hair causing
itching, irritation and hair loss. The life cycle for
these lice takes 27 to 30 days for development
from egg to adult and about seven days for the
eggs to hatch. These lice are most prevalent on
the head, mane, tail base and shoulder area. These
are usually winter parasites, however, they may
be found in Florida in damaging populations at
any time of the year.
Lice are transferred from animal to animal by
contact, movement of flies and occasionally by
contaminated equipment and bedding. All animals
should be checked periodically for infestations
and all animals in infested premises should be
treated for good louse control.
Retreatment of animals is required for good
control because insecticides will not kill the eggs.
With two weeks between treatment of biting lice
and 3 to 4 weeks between treatment for sucking
lice good control will be achieved.

MITES: SKIN SURFACE AND BURROWING
Five different species of mange, scab and itch
mites attack horses. These mites are not usually
prevalent in Florida; however, isolated infesta-
tions may become a problem. These must be con-
trolled to prevent infestations on other horses in
the herd as well as man.


These pests are too small to be seen with the
naked eye but the host damage and reaction
should be easily recognized. The mites associated
with horses belong to two basic groups. Itch,
mange or scabies mites and the chigger or follicle
mites.


Itch or Mange Mites
The itch, or mange mites, are small ovoid mites
about as big around as the cross sections of a
straight pin (1/16 inch). The eight legs are very
short and barely extend beyond the margin of
the body. They burrow just beneath the skin
making very slender winding tunnels from 1/10
to 1 inch long. The fluid discharged at the tunnel
openings dries to form dry nodules.
The female mite dies after laying about 20 eggs
in the tunnel. Eggs hatch in 3 to 10 days into
microscopic 6- legged nymphs. These become 8-
legged after one molt and in two more molts they
reach maturity. The males die after mating. The
females begin new tunnels in 10 to 30 days. after
hatching from eggs.
A generation can be completed in two weeks.
These mites secrete an extremely irritating toxin,
which when combined with the tunneling causes
extreme host reactions and itching. The host re-
action causes the skin to. slough off in the infested
areas.
The mite problem is most prevalent during the
winter but can persist throughout the year. Infes-
tations are contagious and treatment of all ani-
mals in a herd is essential in preventing spread.
Under certain conditions man may contact this
mite.
Infested animals rub and scratch continuously.
Areas of the head, back or base of the tail become
inflamed and scurfy with only scattered hairs re-
maining. The infestation may spread over the
entire body forming large, dry cracked scabs on
the thickened skin. To distinguish it from lice
some scrapings from the affected skin should be
examined for mites.
Itch mites which cause chorioptic mange are
very similar to the former itch mites except they
do not burrow into the skin. Chorioptic mites live
and feed on the skin surface. The life cycle is
similar to the other itch mite with the production
of lesions and mange in the areas of the hocks,
knees and pasterns. They often produce foot
mange. Infested horses are restless and are often
seen biting or licking the lower legs. Infestations
may cause lameness.









Demodectic Mites


The demodectic or follicular mite, is a micro-
scopic (0.23mm), cigarshaped worm-like mite that
lives within the skin. All stages of the life cycle
are often found within the hair follicle and se-
baceous glands. The mite causes nodular lesions
in the skin usually around the neck and shoulders.
Nodules can vary in size from a sixth of a match-
head to the size of a golf ball. The nodules form
from a creamy fluid substance in which the mites
are found.

Little is known of the life cycle of this mite.
Control is difficult because of the depth of the
mites in the skin.



Chigger Mites
Chigger mites redbugss) make up a large
group of species which occasionally cause prob-
lems for both horses and man. They cause intense
itching and reddish welts on the skin.

Adult chiggers do not feed on animals but are
predators on eggs and other small arthropods.
They lay eggs in the soil which hatch to the 6-
legged parasitic "chigger" stage. These seek out
a host. They attach to the skin and begin feeding
by digesting the skin with strong digestive en-
zymes, feeding for 3 to 4 days. This feeding
causes the intense itching and damage. They then
fall off and molt to nonparasitic nymphs and fi-
nally adults. Certain pasture areas may become
heavily infested with chiggers which can cause
massive infections resulting in severe dermatitis
in horses.



Mite Control
Mange control requires isolation of infested
animals and thorough wetting of the whole ani-
mal with timed applications of approved pesti-
cides (see table).
Chiggers can be controlled by application of
detergent wash containing one of the insecticides
registered for other mites. Area control is not
feasible.


TICKS
Two general groups of ticks attack horses.
Hard ticks have a long association with the host,
feed slowly, take a large blood meal, drop from
the host to molt, and lay many eggs. Their mouth-
parts are anterior and may be seen from above.
Ticks are easily distinguished from .insects,
since the body is not definitely divided and the
strong fusion of the thorax and abdomen pro-
duces a sac-like leathery appearance. A distinct
head is lacking, but there is a head-like structure
which bears recurved teeth that are inserted into
the wound, allowing the tick to hold on strongly.
Females can be greatly distended and are bean-
like in form when fully engorged. Ticks have four
developmental stages: egg, 6-legged seed or larval
stage, 8-legged nymphal stage and 8-legged adult.
The two most common species in Florida in-
clude one hard tick, the tropical horse tick, and
the spinosed ear tick. The tropical horse tick in-
fests the ears as a one host tick and can be found
on animals in South Florida. It is a dangerous
vector of babesiosis in horses. The spinosed ear
tick is a soft tick which also infests the ears and
feeds only as larvae and second stage nymphs.
Both ticks can cause severe damage to the ear
and inner ear.
Males, females and immatures all feed on blood
and lymph. A fully engorged female usually de-
posits eggs (from 100 to 18,000) on the ground.
The larval or seed ticks emerging from eggs in
the soil usually climb up grasses or other low
vegetation to contact passing animals. The larvae
molt once into nymphs and go through 1 to 5
nymphal stages. Ticks remain in the 8-legged
form until they emerge as sexually mature adults.
The majority drop off the host to molt after
feeding.
The effects of ticks upon the host include in-
flammation, itching and swelling at the bite site,
blood loss, production of wounds that may serve
as sites for secondary invasion, obstruction of
body openings and paralysis from the injection of
toxic fluids. They also transmit many diseases, in-
cluding anaplasmosis, bovine and equine piroplas-
mosis and tularemia.
Tick control may be attempted through area
or premise control with insecticides. Premise con-
trol kills ticks which are either engorged or on
foliage waiting to contact a host. Animal control
may also be successful with spray or dips.











Table 1. Control of external parasites on horses, ponies and mules

Pest of horses,
ponies and mules Insecticide Formulation Application directions Safety restrictions
Biting Gnats stirofos (Rabon 1% WO Apply to head, neck, belly,
(Culicoides) + back, forelegs and inner
synergized pyrethrum 2% WO surfaces of ears.
+
repellent
Deer Flies stirofos (Rabon) 1% WO or S Ready-to-use. Apply to
+ flanks, back, and belly for
synergized pyrethrum complete coverage.
+
repellent

Horn Flies coumaphos (Co-Ral) S Mix 2 lb of 25% WP in 100
gal water. Apply 'as coarse
spray.
Mix 2 qt of 11.6% EC in 100
gal of water. Apply as
coarse spray.
1% D Apply 2 oz of dust maximum
per animal.

lindane S Mix 1 lb of 25% WP in 100
gal of water. Apply 2 qt
per animal.

lindane S Mix 1'/-2 qt of 1.7%+43.4% Do not treat ani-
+ EC in 50 gal water. Apply mals under 3 months
toxaphene as coarse spray. Repeat as of age, or sick and
necessary every 2-3 weeks. stressed stock.

stirofos (Rabon) 1% WO or S Ready-to-use. Apply to flanks,
+ back and belly for complete
synergized pyrethrum coverage.
+
repellent

Horse Bots coumaphos (Co-Ral) .06% WO Dilute 25% WP in 25 gal of
water (1100-120 F). Apply
as a hand wash to areas
affected with fly eggs. Protect
hands with synthetic rubber
gloves. Do not use in con-
junction with internal
medication.

malathion .12% WO Dilute 1 lb of 25% WP in
25 gal of water (110-120 F).
Same 'as above.

Horse Flies stirofos (Rabon) 1% WO or S Ready-to-use. Apply to flanks,
+ back and belly for complete
synergized pyrethrum coverage.
+
repellent
House Flies stirofos (Rabon) 1% WO Ready-to-use. Apply to head Do not apply di-
+ area especially around rectly to eyes
synergized pyrethrum 2% WO nostrils and eyes. or mucous mem-
+ branes.
repellent

Lice coumaphos (Co-Ral) S Mix 2 Ib of 25% WP in
100 gal of water. Apply as
coarse spray.
Mix 2 qt of 11.6% EC in
100 gal of water. Apply as
coarse spray.


7










Table 1 (Continued). Control of external parasites on horses, ponies and mules


Pest of horses,
ponies and mules


Insecticide


Formulation


Application directions


Safety restrictions


Lice (Cont.) lindane S Mix 1 lb of 25% WP in
100 gal of water. Apply 2 qt
per animal.
lindane S Mix 11A-2 qt of 1.7% + 43.4% Do not treat ani-
+ EC in 50 gal of water.Apply mals under 3 months
toxaphene as a coarse spray. Repeat as of age, or sick and
necessary every 2-3 weeks. stressed stock.
Mange (Sarcoptic, lindane S Mix 11 lb of 25% WP in 100 Do not treat ani-
Psoroptic) gal of water. Apply 2 sprays mals under 3 months
at 7 day intervals, of age, or sick and
stressed stock.
toxaphene S Mix 10 lb of 40% in 100 gal
of water. Apply as coarse
spray. Retreat in 7-10 days.
Mosquitoes lindane S Mix 114-2 qt of 1.7% + 43.4% Do not treat animals
+ EC in 50 gal of water. Apply under 3 months of
toxaphene as coarse spray. Repeat as age, or sick and
necessary every 2-3 weeks, stressed stock.
stirofos (Rabon) 1% WO or S Ready-to-use. Apply to flanks,
+ back and belly for complete
synergized pyrethrum coverage.
+
repellent
Screwworm coumaphos (Co-Ral) 5% D Thoroughly dust wound and
surrounding area.
S Mix 8 lb of 25% WP or 8 qt
of 11.6% EC in 100 gal of
water. Apply as coarse spray.
Stable Flies lindane S Mix 1 lb of 25% WP in 100
gal of water. Apply 2 qt
per animal.
lindane S Mix 1/4-2 qt of 1.7% + 43.4% Do not treat ani-
+ EC in 50 gal water. Apply mals under 3 months
toxaphene as coarse spray. Repeat as of age, or sick and
necessary every 2-3 weeks. stressed stock.
stirofos (Rabon) 1% WO or S Ready-to-use. Apply to
+ legs and flanks.
synergized pyrethrum 2% WO
+
repellents
Ticks (Ear) coumaphos (Co-Ral) 5% D Dust ear and surrounding
area by blowing dust in ear.
S Mix 4 lb of 25% WP or 4 qt
of 11.6% EC in 100 gal of
water. Apply as a coarse spray.
Ticks (Hard) lindane S Mix 1 Ib of 25% WP in 100
gal of water. Apply 2 qt
per animal.
lindane S Mix 1'-2 qt of 1.7% + 43.4% Do not treat ani-
+ EC in 50 gal of water. Apply mals under 3 months
toxaphene as coarse spray. Repeat as of age, or sick and
necessary every 2-3 weeks, stressed stock.


Key to Abbreviations


D =dust


S = spray


WO =wipe-on










Table 2. Insecticides labeled for internal control of stomach bots in horses
Effectiveness
Insecticide Formulation Directions Warnings (% control in tests)
butonate stomach tube veterinary appli- 100%
cation only
carbon disulfide stomach tube veterinary appli- 100%
cation only

carbon disulfide + stomach tube veterinary appli- 100%
piperazine or balling gun cation only
dichlorvos 20% powder 14.2-18.5 mg/lb veterinary consulta- 93-100%
oral feed additive tion recommended (2nd instar)
0-100%
(3rd instar)

37% gel 32 cc/1200 lb orally veterinary appli- 54-100%
by syringe cation only
34% resin 1.6 gm/100 Ib veterinary consulta- 100%
tion recommended

trichlorfon 90% powder 5 gm/250 lb oral veterinary consulta- 100%
feed additive tion recommended



Table 3. Control of pests around horse farms and other animal buildings (non-food)
Pest Insecticide Formulation Application directions
Fleas stirofos (Rabon) 0.5% S Mix 1 gal of 23% EC in 50
+ gal of water. Thoroughly
dichlorvos (Vapona) treat infested areas.
Fly Maggots dichlorvos (Vapona) .5% S Mix 1 gal of 23.4% EC in 25
gal of water. Apply 1-2 qt
to every 100 sq ft of fly
breeding area. Repeat in
7-101 days.
dimethoate (Cygon) S Mix .5 pt of 23.4% EC in 5 qt
water. Apply to fly-breeding
areas such as manure piles.

ronnel (Korlan) 2% B Mix 2 gal of 24% EC in 25 gal
of water with 3 oz of sugar
per gallon. Spray or sprinkle
areas where flies congregate
at 1-2 day intervals as needed.
stirofos (Rabon) 1% S Mix 1 gal of 23.4% EC or 4
lbs of 50% WP in 25 gal of
water. Apply 1 gal of spray
per 100 sq ft of manure area.
Repeat every 7-10 days.
stirofos (Rabon) 1% + .25% S Mix 1 gal of 23% EC in 25 gal
+ of water. Apply by spraying
dichlorvos (Vapona) or sprinkling 1 gal to 100 sq
ft of manure, wet straw and
around fly breeding areas.
Repeat every 7-10 days.
Gnats dichlorvos (Vapona) .5% M or F Mix 1 gal of 43.2% EC in 96
gal of water. Apply 1 qt per
8000 cu ft.
20% RS Hang one resin strip per 1000
cu ft of enclosed area.
Replace strip as needed.









Table 3 (Continued). Control of pests around horse farms and other animal buildings
(non-food)


Application directions


Safety restrictions


Gnats (Cont.)


dichlorvos (Vapona)


1% M or F


Mix 1 gal of 23.4% EC in 25
gal of water or 28 gal of oil
for 1% M or F. Apply 1 qt
per 8000 cu ft.


naled (Dibrom) 1% M Ready t o use. Apply 1 oz per
3000 cu ft.
M Mix 1 qt of 36% EC in 40 gal
of water. Apply 1 oz per
3000 cu ft.
B Mix 1 tsp of 36% EC in 1 lb
of sugar. Scatter bait on floors
where flies congregate.
stirofos (Rabon) 1% + .25% S Mix 1 gal of 23% EC in 25 gal


+
dichlorvos (Vapona)


dichlorvos (Vapona)


of water. Remove cobwebs and
dust from surfaces. Apply 1%
spray to fly resting areas, 1
gal for every 500-1000 sq ft.


.5% M or F Mix 1 gal of 43.2% EC in 96
gal of water. Apply 1 qt per
8000 cu ft.


20% RS Hang one resin strip per 1000
cubic ft of enclosed area.
Replace strip as needed.
1% M or F Mix 1 gal of 23.4% EC in 25
gal of water or 28 gal of oil
for 1% M or F. Apply 1 qt
per 8000 cu ft.
dimethoate (Cygon) S Mix 1 pt of 23.4% EC in 3 gal
of water. Apply to areas
where flies rest at 1 gal per
500-1000 sq ft.
fenthion (Baytex) 1.5% S Mix 4 fl oz of 45% EC per gal
of water. Apply 1 gal per 500
sq ft to surfaces frequented
by flies. Apply to structures
as residual spray.
malathion S Mix 1 qt of 57% EC in 12 gal
of water. Apply 1 gal per 1000
sq ft to areas where flies
congregate.
B Mix 1 qt of 57% EC and 2.5 lb
sugar in 12 gal of water.
Apply as bait spray to manure.
Spray dry bedding within 18
inches of wall. Do not reapply
within 14 days.
naled (Dibrom) 1% M Ready to use. Apply 1 oz per
3000 cu ft.
M Mix 1 qt of 36% EC in 40 gal
of water. Apply 1 oz per 3000
cu ft.
B Mix 1 tsp of 36% EC in 1 lb
of sugar. Scatter bait on floors
where flies congregate.
pyrethrins .03% + .25% M Ready to use. Apply 2 oz per
+ 1000 cu ft.
piperonyl butoxide


Pest


Insecticide


Formulation


House Flies










Table 3 (Continued). Control of pests around horse farms and other animal buildings
(non-food)
Pest Insecticide Formulation Application directions Safety restrictions
House Flies (Cont.) ronnel (Korlan) .5% S Mix 2 qt of 24% EC in 25 gal
of water. Spray walls, ceilings,
partitions with 1 gal per 500
sq ft. Add 3 oz of sugar per
gal for increased effectiveness.

ronnel (Korlan) 1% S Mix 1 gal of 24% EC in 25 gal
of water. Spray walls, ceilings
and partitions with 1 gal per
500 sq ft. Add 3 oz of sugar
per gal for increased
effectiveness.

2% B Mix 2 gal of 24% EC in 25 gal
of water with 3 oz of sugar per
gallon. Spray or sprinkle areas
where flies congregate at 1-2
day intervals as needed.

stirofos (Rabon) 1% + .25% S Mix 1 gal of 23% EC in 25 gal
+ of water. Remove cobwebs and
dichlorvos (Vapona) dust from surfaces. Apply 1%
spray to fly resting areas, 1
gal for every 500-1000 sq ft.

trichlorfon (Dylox) S Mix 5 lbs of 80% WP in 40 gal
of water. Apply 1 gal per 500
sq ft. Apply t o floors, walls,
ceilings. Spray bedding areas
after removal of animals. For
longer residual add 1 lb of
sugar per gallon.

Mosquitoes dichlorvos (Vapona) .5% M or F Mix 1 gal of 43.2% EC in 96
gal of water. Apply 1 qt per
8000 cu ft.
20% RS Hang one resin strip per 1000
cu ft of enclosed area.
Replace strip as needed.
1% M or F Mix 1 gal of 23.4% EC in 25
gal of water or 28 gal of oil
for 1% M or F. Apply 1 pt
per 8000 cu ft.
fenthion (Baytex) 1.5% S Mix 4 fl oz of 45% EC per gal
of water. Apply 1 gal per 500
sq ft to surfaces frequented
by flies. Apply to structures
as residual spray.

naled (Dibrom) 1% M Ready to use. Apply 1 oz per
3000 cu ft.
M Mix 1 qt of 36% EC in 40 gal
of water. Apply 1 oz per 3000
cu ft.
B Mix 1 tsp of 36% EC in 1 lb of
sugar. Scatter bait on floors
where flies congregate.
ronnel 1% S Mix 1 gal of 24% EC in 25 gal
of water. Spray 1 gal per 1000
sq ft where pests are found.
stirofos (Rabon) 1% + .25% S Mix 1 gal of 23% EC in 25 gal
+ of water. Remove cobwebs and
dichlorvos (Vapona) dust from surfaces, Apply 1%
spray to fly resting areas, 1 gal
for every 500-1000 sq ft.









Table 3 (Continued). Control of pests around horse farms and other animal buildings
(non-food)
Pest Insecticide Formulation Application directions Safety restrictions

Spiders ronnel 1% S Mix 1 gal of 24% EC in 25 gal
of water. Spray 1 gal per 1000
sq ft where pests are found.
stirofos (Rabon) 1% + .25% S Mix 1 gal of 23% EC in 25 gal
+ of water. Remove cobwebs and
dichlorvos (Vapona) dust from surfaces. Apply 1%
spray to fly resting areas. 1 gal
for every 500-1000 sq ft.
Stable Flies pyrethrins .03% + .25% M Ready to use. Apply 2 oz per
+ 1000 cu ft.
piperonyl butoxide
stirofos (Rabon) 1% + .25% S Mix 1 gal of 23% EC in 25 gal
+ of water. Remove cobwebs and
dichlorvos (Vapona) dust from surfaces. Apply 1%
spray to fly resting areas, 1
gal for every 500-1000 sq ft.
Ticks stirofos (Rabon) 0.5% S Mix 1 gal of 23% EC in 50 gal Do, not apply to
+ of water. Thoroughly treat flowers and shrubs.
dichlorvos (Vapona) infested areas.
Wasps fenthion (Baytex) 1.5% S Mix 4 fl oz of 45% EC per gal
of water. Apply 1 gal per 500
sq ft to surfaces frequented by
flies. Apply to, structures
as residual spray.
stirofos (Rabon) 1% + .25% S Mix 1 gal of 23% EC in 25 gal
+ of water. Drench nests with
dichlorvos (Vapona) spray in evening when wasps
are quiet.


Key to Abbreviations B = bait F = fog M = mist RS = resin strip S = spray

















Single copies are free to residents of Florida and may be obtained from the County Extension Office. Bulk rates are available upon
request. Please submit details of the request to C.M. Hinton, Publication Distribution Center, IFAS Building 664, University of Florida,
Gainesville, Florida 32611.


This publication was promulgated at a cost of $904.86, or 18 cents per copy to inform horse owners
on the biology and control of external parasites on horses.








































I DA


4-5M-77


COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS
(Acts of May 8 and June 30, 1914)
Cooperative Extension Service, IFAS, University of Florida
and United States Department of Agriculture, Cooperating
K. R. Tefertiller, Director




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