Insects in relation to national defense


Material Information

Insects in relation to national defense
Series Title:
Its Circular no. 1-23. Feb. 1941-Jan. 1944
Also known as:
Insects in relation to national defense, circular
Physical Description:
24 nos. in 1 v. : ill., photos., map, plans, diagrs. ; 23 cm.
United States -- Bureau of Entomology and Plant Quarantine
U.S. Govt. Print. Off.
Place of Publication:
Publication Date:


Subjects / Keywords:
Beneficial insects   ( lcsh )
Insect pests   ( lcsh )
Insecticides   ( lcsh )
Fumigation   ( lcsh )
World War, 1939-1945 -- Health aspects   ( lcsh )
non-fiction   ( marcgt )


General Note:
Reproduced from type-written copy.
General Note:
Includes bibliographical references.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 029081698
oclc - 09471812
lcc - SB931 .U44
System ID:

Full Text




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April 1942

Digitized by the Internet Archive
in 2013 11




Circular 12 Ticks

Table of Contents


Introduction.............................. 1
Kinds of Ticks...... ... ...... ..... 3
Life Histories andHabits................. 6
How to Avoid Tick Attack and Infection.... ll
Precaution Against Tick Bites........... 12
How to Reduce the Danger of Disease
Infection by TickBites............... 13
Control of WoodTicks..................... 16
Control of the Brown Dog Tick............. 19
Control of Horse Ticks and Cattle Ticks... 22
The Spinose EarTick...................... 23
References.. ...... . ... . . . .. ..... .. ... 24


Several species of ticks freely attack
people. Some of these carry diseases and others
are more important as annoyers either by their
presence or by their bites. Certain kinds of
ticks are also important as parasites or trans-
mitters of diseases of domestic animals, poultry
and livestock.
Ticks, although often referred to as in-
sects, are not true insects, but arachnids, re-
lated to the mites and spiders. They feed only
on the blood of animals, to which they attach
themselves by burying their mouthparts in the
skin. Although mating of males and females fre-
quently occurs while the females are attached to

Circ'lL[r 12 Ticks

.n animal and feeding, eggs are never laid while
the feliale is still on the host, but only after
it has dropped to the ground. For this reason,
an increase in the infestation of ticks on an
animal occurs only by the attachment of other
ticks and never by the breeding on the animal of
those c,'ready attached.

Ticks are widely distributed geographically,
but in any one locality their occurrence is usual-
ly limited to a few favorable areas. Certain
species are iaost comionly found on one's clothing
or attached to one's person after walking through
areas covered with brush or high grass. Other
species are encountered attached to dogs, horses,
and other domestic ani:ials. :liany species are
found attached only to wild animals, such as opos-
sums, sklunks, rabbits, or field mice. Some infest
dry caves, ana some frequent the bedding places of
deer and other animals, ready to feed on sleeping
animals or persons. One species frequently in-
fests houses and buildin-s.

Rocky L.ountain spotted fever of man is car-
ried by the common wood tick (Dermacentor andersoni
Stiles) in the Rocky mountainn region, and by the
American do.- tick (D. variabilis (Say)) in the Mid-
dle westernn and Eastern S3tates. Both species may
also transmit rab oit fever or tularaeimia. In the
case of h^'th of these diseases only a small per-
centare of the ticks are infected. A form of as-
cending paralysis is also caused occasionally by
the attachment of these ticks especially at the
base of the head. The symptoms usually subside when
the parasite is re.ioved. Relapsing fever is trans-
mitted by several species belonging to the genus
Ornithodoros which occur in the ".est and Southwest.
Tne cattle tick, Boophilus annulatus Say, carrier
of tick fever of cattle, has now oeen eradicated
from most of the United Dtates, but is still to be
found in parts of Texas and iFlorida and in the
Caribbean region. Ticks are frequently sufficient-
ly abundant to cause serious injury to animals
through direct irritation and loss of blood.

Circular 12 Ticks

The spinose ear tick, Ornithodoros mecgnini
Duges, often gives serious trouble by attaching
itself deep in the ears of man, horses, and other

In tropical Africa the tick, Ornithodoros
moubata (Jurray), is common in habitations of man
and animals, and transmits Af'rican relapsing fever
of man. -Human tick bite fever of Louren9go .arques
is transmitted mainly by the larvae of uAmblyomma
hebraeuxi Koch.

Australian human tick paralysis is caused
by either Ixodes ricinus (L.) or I. holocyclus
(Neuna.). This disease does not appear to be very
common and its cause is similar to that of the
tick paralysis referred to above.


There are tvo .m-ain groups or families of
ticks: those with a flexible or leathery body
(Argasidae), fig. 1., and those with more or less
armored or. hErd body (Ixodidae), fig. 2.

Fig. 1 A soft-bodied
tick. The fowl tick,
Argas miniatus Koch,

Circular 12 Ticks

-- Fig. 2- A hard-bodied
In P :. tick. The Rocky I:oun-
i 1tain spotted fever tick,
Dermiacentor andersoni
-( Stiles) nale.

Several different kinds of ticks are en-
countered in the woods and brush, and these are
often spoken of as "wood ticks." These attack
man more or less freely and also attach themselves
to livestock. The species commonly referred to
as wood ticks are often different in various sec-
tions of the country, and therefore common names
which are more specific have been assigned.
These species and their distribution are indi-
cated below. The males have the backs covered
with a hard shell and often present quite a dif-
ferent appearance fro:a the females. The females
have a hard plate shieldu, or scutum) over the
head end of the body. The rear portion being
capable of great distention as blood is imbibed.
The newly hatched tick (larvae or seed ticks) and
the nymphs (second stage) have a similar shield.

Circular 12 Ticks

The Rocky Mountain spotted fever tic!:, D.
andersoni Stiles, is widely distributed in the
Rocky Mountain region. The American dog tick, D.
variabilis Say, occurs in many states outside tHe
Rocky Mountain region. It is most abundant in
the Atlantic coastal areas and the Mississippi
Valley. The Pacific coast tick, D. occidentalis
Mliarx, occurs in California and Oregon. The lone
star tick, Amblyorma a'aericanum (L.), is found
from Texas to Ilissouri and eastward to the -_t-
lantic coast. The Cayenne tick, A. cajennense
(Fabr.), is a troublesome species in southern
Texas, `exico, the giest Indies, and parts of Cen-
tral and South America. The black-legged tick,
Ixodes ricinus scapularis (Say), is common in the
Gulf and Atlantic Coast states; and I. r. califor-
nicus (Banks), the California black-legged tfT-c-,
in the Pacific Coast states. the soft-bodied ticks of the genus
Ornithodoros there are several species which super-
ficially reserable each other in the seed tick and
nymphal as well as the adult stages. These are
found mainly in caves, hollow trees, and the bur-
rows of animals. The males and females are capa-
ble of engorgement with blood. Another soft-
bodied species is the fowl tick, Argas miniatus
Koch, which is a serious pest of poultry and oc-
casionally bites man, fig. 1.

One of this group, the spinose eartick, 0.
megnini Duges, is prevalent in the arid and semi-
arid southwestern United States, Mexico, and Cen-
tral America. Another species, known as Orni-
thodoros turicata Duges, that is found in caves
and animal burrows frequently invades houses and
other buildings and freely attacks man. It is
known to transmit relapsing fever to man. This
is also true of several closely related species.


Circular 12 -Ticks

Because of the similarity in appearance
of many species of ticks, accurate identification
of the species can be made only by a specialist
familiar with the distinguishing characters. The
Bureau of Entomology and Plant Quarantine, United
States Department of Agriculture, Washington,
D. C., will identify specimens submitted. Speci-
mens should be preserved in small vials of 70%
alcohol or 2% formalin. If well packed in ab-
sorbent material to prevent breakage and leakage,
they may be these containers. If al-
cohol or formalin is not available, specimens may
be lightly crushed and placed between folds of
paper prior to mailing. All specimens should be
accompanied with information as to locality and
date of collection, conditions where found, in-
cluding kind of animal with which associated.


The life history and habits of different
kinds of ticks vary greatly.

All ticks pass through at least three
stages of development: the egg (fig. 3), the
seed tick or larva, having six legs (fig. 4),
the nymph (fig. 5), and the adult, male and fe-
male (figs. 6 and 7). In general, ticks feed upon

Fig. 3 Female tick with egg mass.

Circular 12 Ticks

?i:. 4 Seed tick or larva, unengorged.
tick, Der 2.acer.tor variabilis (Say).

American dog

Fig. 5 Nymph, unengorged. American dog tick, Derma-
centor variabilis (Say).

Circular 12 Ticks

Fi.. Hale.
bilis (Say).

Ai'erican do tick, Dermacentor varia-


^ 4,

Fig. 7 Fernal., unen.orged. American dog tick, Derma-
centor variabilis (Say).

Circular 12 Ticks

blood in the seed tick, nymphal, an adult stages,
and molt their skins between each feeding. There
may be two or more nymphal stages in the case of
the soft-bodied ticks. The soft-bodied ticks
also differ from the others by their habit of
filling quickly with blood (30 minutes to an hour)
and hiding away much as do bed bugs, while the hard
back ticks remain attached for several days (5 to
15 or even longer). Another distinct difference
is that the soft-bodied ticks may feed several
times as adults, the females depositing a mass of
eggs between blood meals. The females of the hard-
back ticks, on the other hand, become greatly dis-
tended with blood, then drop off, seek protected
places on the ground, deposit several th usand
eggs, and die (fig. 3).

The incubation period in most species varies
from 2 or 3 weeks in warm weather, and as a rule
the minute seed ticks are soon ready to attach
themselves to a suitable host. The seed ticks and
nymphs of some species such as the lone star tick
and the cayenne tick (Amblyomma cajennense) of the
tropics will attach themselves to man or most any
warm-blooded animal. The seed ticks frequently
crawl upon grass and cluster together in large
masses. '1hen these are touched by a man or other
animal they cling to it and start crawling about
rapidly and soon attach. These young stages of
the spotted fever tick and American dog tick, how-
ever, rarely or never attack man. The young of
the former mainly attach to and engorge on wild
animals such as chipmunks, ground squirrels, and
woodchucks; those of the latter, on wild mice
(fig. 8). The engorgement period of seed ticks is
2 days to 2 weeks and that of the nymphs slightly
longer. The molting period of seed ticks ranges

10 Circular 12 Ticks

Fig. S Engorged n;.-nphs of the AVari" can dog tick
attached to a meadow mouse.

from about 1 to 5 weeks and that of nymphs from
2 to 6 weeks, during moderate weather. The maxi-
mum length of life of these stares is from 7 to
10 months, or even loni-er under very favorable

Most ticks are long lived. The adults of
some kinds may live 5 or miiore years without feed-
ing. The males as well as the feir.ales of Aost
species bite, but the former do not greatly dis-
tend with blood; the shell-like covering of tneir
backs (fig. 6) prevents this.

In the case of many kinds of hard-back ticks
such as the American dog tick the engorged seed
ticks and nymphs drop to the ground and molt in
protected places. Some other kinds of ticks such
as the cattle fever tick (LIar.-aropus annulatus)
and the winter tick (Dermacentor albipictus Pack.)
attach themselves to the host as seed ticks, en-
gorge, molt to nymphs, and again attach themselves,
engorge, and molt to adults without leaving the
host until they drop as engorged females.

Circular 12 Ticks 11

As indicated, some ticks will feed upon
almost any kind of host; others attack only one
or a few species. The brown dog tick (Rhipice-
phalus sanguineus Latr.) is of the latter class
as it rarely attaches to any animal but the dog.
The cattle fever tick is also restricted in its
hosts, developing mainly on cattle, horses, and


Since all ticks are pests of man or.some
animal and are potential disease carriers they
should be destroyed and their bites avoided as
far as possible. This is more important, of
course, where human diseases such as Rocky MIoun-
tain spotted fever, tularaemia, and relapsing fever
commonly occur. The species commonly spoken of as
"wood ticks" are most likely to attack man and
these are the carriers of Rocky Mountain spotted
fever and tularaemia.

Rocky Mountain spotted fever is widespread
in the United States, having been reported in all
the states of the Union with the exception of
Wisconsin, Kansas, Connecticut, Vermont, New Hamp-
shire, and Maine. The prevalence of the disease
is closely correlated with the abundance of the
ticks that carry it. The disease is much more
prevalent in the northern Rocky Mountain regions
and along the Atlantic Seaboard than elsewhere in
the country, although a number of cases occur in
some of theCentral States, notably Iowa. The
virulence of the disease varies in different areas.
The most virulent form occurs in the Bitterroot
Valley, Montana, and portions of Wyoming. In
these areas the mortality runs from 60 to 75 per-
cent. The form of the disease occurring in Idaho,

12 Circular 12 Ticks

Washington, and Oregon is milder, the mortality
running about 5 to 10 percent. In the eastern
United States the virulence is intermediate, the
mortality running from 20 to 25 percent. The
danger of infection is, of course, dependent very
largely on the abundance of ticks, although even
in the areas where the disease occurs most com-
monly, only a small percentage of the ticks found
in nature are infected. The number of infected
ticks usually runs from 1 in 200 to 1 in 600.

Precaution against tick bites

When man is in tick-infested areas precau-
tions should be taken to avoid tick bites and pos-
sible infection. Wearing high-top shoes or leg-
gings, or wearing the socks over the bottom of the
trousers is helpful. Most ticks crawl up from the
ground or low vegetation, and the above precau-
tions tend to keep them from crawling beneath the
clothing. An occasional glance over the clothing
will detect the presence of the adult ticks before
they reach the belt or neckline or have an oppor-
tunity to get underneath the clothing. The minute
seed ticks and relatively small nymphs are more
difficult to detect and exclude. When masses of
seed ticks are seen to attach to clothing many of
them can be brushed off. An occasional light spray-
ing of the clothing with kerosene extract of
pyrethrum as one traverses areas where these young
ticks arc abundant is helpful in keeping them off.
Pyrethrum, derris, or cube powder lightly dusted
in the inside of the outer clothing also lends pro-

By keeping the possibility of t.ick infesta-
tion in mind, one will be more likely to feel them
when they start to crawl on the skin, and so remove
them before they have become attached.

Circular 12 Ticks

After walking in tick-infested areas it is
well to exa:,iine the outer clothing thoroughly,
especially in the folds and under the collar, be-
fore entering automobiles or buildings. If ticks
are very abundant in the area traversed, clothing
should be removed and fumigated upon coming in
from the field. If thegarments are dropped
loosely into a large metal container, such as a
25-pound lard can, and two teaspoonfuls of carbon
tetrachloride poured over them, or the fumigant
placed in a sriall open dish set on top of them,
and the can tightly closed, all ticks will be
killed in 8 hours. One should never sleep in
clothing that was worn during the day, and field
clothing should not be thrown on bedding when
there is danger of tick infestation. Clothing
of troops returning from maneuvers in tick-infested
areas may be fumigated in bulk in any available
tight containers.

Examine the body thoroughly for attached
ticks upon retiring and arising; better still, let
individuals examiine each other. Pay particular
attention to the hairy parts, especially the back
of the head. Ticks often lie very close to the
skin when first attached and are easily overlooked.
Combing the hair upward with a fine-toothed comb
helps reveal the presence of ticks. Prompt re-
moval of attached ticks will prevent the develop-
ment of tick paralysis.

Avoidance of bites of the soft-bodied ticks
(Ornithodoros) is not easy. In choosing temporary
camp sites it is well to avoid areas inhabited
with ground squirrels, wood rats, and other manmaals.
It is advisable not to sleep on the floor of huts
in the warmer parts of the world as such a practice
gives opportunity for ticks of this group to bite
during the night.

How to reduce the danger of disease infection by
tick bites

If a tick is found attached, remove it at
once by grasping it with the fingers or a pair of

14 Circular 12 Ticks

tweezers and pulling slowly and steadily. Care
should be taken to prevent breaking off the mouth-
parts before they are removed from the skin. In
many species, such as the carriers of Rocky Moun-
tain spotted fever, the American dog tick, and
the Rocky Mountain wood tick, there is little
danger of this, but in the case of the lone star
tick and others having exceptionally long mouth-
parts, it sometimes occurs. If a bit of skin is
pulled off with the tick it is evident that the
mouthparts have not broken off. If it appears
that the mouthparts have been left in the skin,
they should be removed at once by excision. Ticks
should never be allowed to remain attached for
several hours. After the tick has been removed
it is well to disinfect the point of attachment
with a solution of carbolic acid or silver nitrate.
Iodine may be used if the other materials are not
at hand. This can best be done by dipping the
point of a round wooden toothpick in the solution,
then drilling it lightly into the skin at the
exact point of attachment.

Infection may be derived from the blood of
crushed ticks if it gets into the eye, nose, or
mouth, or into a skin abrasion. Therefore, when
one is called upon to de-tick animals repeatedly,
it is better to use an insecticide rather than to
pick the ticks by hand. If the ticks are picked,
they should be handled with a pair of small forceps,
using ca.e to avoid tearing them open. They should
then be dropped at once into boiling water, kero-
sene, turpentine, or alcohol. Keep the hands away
from the eyes, nose, and iaouth while working, and
wash them thoroughly with soap and water when the
job is finished. Do not allow the ticks that have
been removed to escape, as they may reattach them-
selves to persons, and are rore likely, if infected
with spotted fever, to transit the disease by a
short period of attachment.

Circular 12 Ticks

A vaccine protective against Rocky ".:oun-
tain spotted fever is obtainable from the United
States Public Health Service, but its production
is limited.
Jhen a person is suspected of having con-
tracted Rocky MIountain spotted fever, all urnneces-
sary physical exertion should be avoided and the
patient promptly hospitalized under medical care.
The incubation period of spotted fever in man is
2 to 12 days.
The same precautions are applicable to
tularaemia (rabbit fever).
Some species of ticks, Ornithodoros (fig.9),

Fig. 9 A relapsing
fever tick, Ornithodoros
turicata (Du s) fe-

transmit relapsing fever, and in the areas where
these ticks occur special precautions must be taken
to avoid being bitten by them. Ticks of this genus
do not crawl about on the body as long as do wood


16 Circular 12 Ticks

ticks before attaching themselves, and may remain
attached for only a few minutes, but this short
period is sufficient to permit the infected ticks
to transmit the disease. One species, 0. turicata,
frequents dry limestone caves in certain parts of
Texas, and its attack is so quick that it is almost
impossible to enter such caves without being bit-
ten. One should avoid all caves, overhanging em-
bank-ents, rock led.. es, r-nd similar places in the
infected region. Other species frequent dry woods,
the burrows of rodents, and occasionally invade
cabins. They are much more difficult to avoid,
but fortunately their distribution is quite loca-
lized in the NVestern States, particularly Texas
and California. when one is known to have been
bitten by these ticks, and high fever and chills
develop about one week later, medical care should
be administered promptly.


It is very difficult to eradicate wood
ticks from extensive areas, but certain measures
may be taken to reduce their abundance in restricted
localities. The abundance of all species may be
reduced by clearing out vines and underbrush from
wooded areas. The brush, grass, and weeds should
be kept closely cut in unused fields, particularly,
near dwelling places. Close grazing of brushy and
weedy areas with sheep does much to reduce tick
abundance. If fine-wooled sheep, such as rambouil-
lets, or merinos, are used, relatively few ticks
become engorged on them and many are killed by the
wool grease. These methods render the areas un-
favorable for the adult ticks, and also drive out
the rodents and ground birds on which the immature
ticks develop. Burning of underbrush has been
thought efficacious in reducing the numbers of
tic- s, but i:is rrctice has many disadvantages.

In the case of the American dog tick, the
most widely distributed species, considerable re-
duction in tick abundance may be achieved by

Circular 12 Ticks

control of the meadow mice on which the immature
ticks develop, by the use of poisoned baits. As
the use of these baits involves a certain amount
of danger to the operator and to domestic animals,
they should be distributed with great care and
under trained supervisors. As meadow mice often
cause considerable losses in orchards, the Fish
and Wildlife Service of the 'U. S. Department of
the Interior has developed reliable methods for
their control that are adaptable to cantonment

The Fish and Wildlife Service considers
starch-coated grain bait as probably nost satis-
factory for this purpose. This bait and its use
are described by James Silver in Farmers' Bulle-
tin 1397. It is prepared as follows:

Mix 1 tablespoon of gloss starch in one-
fourth teacup of cold water and stir into
three-fourths pint of boiling water to
make a thin clear paste. Mix 1 ounce
of powdered strychnine with 1 ounce of
baking soda and stir into the starch to
a smooth creamy mass free of lumps. Stir
in one-fourth pint of heavy corn sirup
and 1 tablespoon of glycerin or petrolatum.
Apply to 12 pounds of wheat or preferably
steam-crushed whole oats and mix thor-
oughly to coat each kernel.

The bait should be put out in October or
November and again later in the winter if fresh
signs of mice are present. To prevent birds from
getting the bait and to protect it from the
weather it is advisable to use "poison stations."
For this purpose small drain tiles or tunnels
made of wood or galvanized iron may be used. A
teaspoonful of the bait is put in each and the
stations are located in a dry place where the mice
normally run. It is well to cover them with coarse
brush but not grass, as the latter makes them too

Circular 12 Ticks


When dogs are kept in ticky areas they become
heavily infested with engorging ticks. This not
only results .in loss of condition of the dogs, but
increases the possibility of persons coming in
contact with infected ticks, and produces numerous
engorged female ticks to increase the general in-
festati'-i in the region. In such cases, dogs
should Ub '--t as nearly free of ticks as possi-
ble, and those ticks which do become attached should
be killed quickly. This may best be accomplished
by the application of a derris dip made of 2 ounces
of derris or cube powder and 1 ounce of neutral
soap to a gallon of lukewarm water. (The powder
should contain at least 3 percent rotenone.) It
is best to make a paste of the powder with a small
amount of the water, then add it to the rest of
the water.

The dip may be applied by putting the dog
in a tub containing it, or it mLnay be used as a
wash buat in either case care should be taken to
wet the skin thoroughly, as well as the hair, over
the entire body. The dip can be kjpt for at least
a week without deterioration. If the dip cannot
be used conveniently, derris powder may be dusted
onto the skin on all infested parts. This method
is less satisfactory, and applications should be
made evcj second day. The powder or dip must not
be allowed to get tato the eyes, as it is very ir-

When the infestation is restricted to a
very small area, many of the ticks on the vegeta-
tion may be killed by thoroughly applying a spray
consisting of one part of nicotine sulphate (40%
nicotine), 1 part of soap, and 288 parts of water.
This is about 8 teaspoonfuls of nicotine sulphate
and 1/2 ounce of soap to 3 gallons of water.

Caution: Remember that 40 percent nicotine
is a violent poison wnich must not be taken into
the mouth or allowed to remain on the skin. It
should be kept in plainly marked containers and in
a secure, safe place.

Circular 12 Ticks

The brown dog tick (Rhipicephalus sanguineus
(Latr.)), (figs. 10 and 11), is an important pest

fFig. 10 The brown dog
tick, Rhipicephalus
wsanguineus (Latr.).
Mal e.

Fig. 11 The brown dog
Jtick, unengorged,
Rhipiceahalus sanguineus
77Tat.) Female.

Circular 12 Ticks

of doss, but it does not attach itself to man. It
is not known to carry any disease in this country
except canine piroplasyaosis, which is not wide-
spread. It often causes considerable annoyance to
man by infesting houses where dogs are kept.

The brown dog tick may complete its entire
life cycle in outbuildings and residences, produc-
ing increasingly heavier infestations, providing
the building is heated in winter and a dog is
present on which the tic-s may engorge. All the
developmental stages of this tick--larvae, nymphs,
and adults--engorge on dogs, and very rarely on
other large animals. As in the case of wood ticks,
the larvae and nymphs drop from the host to molt,
and the females drop to lay eggs.

This tick is a native of the warmnner regions
of the United Stat.s where it lives outdoors as
well as i- buildings, and it is becoming widely
established i. the colder regions in kennels, houses,
and'other buildin-s, vhoere it is protected' from low
winter temperatures.

The tick may be controlled on dogs by use
of the derris or cube dip reconiended forthe con-
trol of wood ticks.

Infested dor, holdd oe er%4- 'i one place,
especially duriiin their sletpi hours. This more
or less confines the ticls to that place and makes
the treatment easier. The kennels in which the
infested animals sleep should t*r 'hoiouchly sprayed
with creosote oil without t dilution. This material
is the same as that used for the prevention of de-
cay of posts and trbers.

Cation: Creosote oil stains and is very
caustic; tnoreforL, i, .-:.nioulc not be used in houses
and should not u allowed to come in contact with
ani.a s or plants. It penetrates wood and cracks

Circular 12 Ticks 21

and can be relied upon to destroy with a single
treatment practically all the ticks in the build-
ing. If corrugated or other metal kennels or cages
are being used it is best not to use the creosote
oil but to spray with one of the creosote dips or
disinfectants because the creosote oil remains on
the metal and will burn the dogs. The strength
of creosote dip should be used at triple the strength
usually recommended on the container for disinfect-
ing purposes. The dilution for ticks would usually
be about 1 part of dip to 25 parts of water.

The use of a gasoline torch or pear-burner
in concrete or other fireproof buildings is satis-
factory for the destruction of the ticks in the
cracks and floors.

When buildings become infested with ticks
it is best to keep the dogs out of doors except
when they are allowed to enter to serve as traps
for the free ticks. The baseboards, window casings,
and other infested places should be sprayed fre-
quently with one of the standard fly sprays, see
Circular 21, which are essentially kerosene con-
* training a small amount of pyrethrum extract. The
ticks are quite resistant to sprays of this kind
and must be wetted thoroughly if they are to be
killed. In addition to the spray, the use of fresh
pyrethrum powder scattered behind baseboards and
other hiding places is advised. If the dog is kept
indoors it should be treated regularly as outlined
above. The treatment of the dog and the premises
must be persisted in for several months to eradicate
the pest.

Fumigation of infested houses is seldom ad-
visable because the ticks are usually present in
entryways, around porches, and in outbuildings where
they cannot be reached with a fumigant. Further-
more, the tick is very resistant to. fumigants.

Circular 12 Ticks


Horses and cattle are not only subject to
attack by the wood ticks, but also by three species
of ticks of a different type. These are the cattle
ticks, Boophilus annulatus and B. a. microplus Can.
the winter ticks, Dermacentor albipictus (Pack.),
and D. nigrolineatus (Pack.), and the tropical horse
tick-, D. nitens Neum. The winter ticks are widely
distributed in the United States, while the cattle
ticks and the tropical horse tick occur in the ex-
treme Southern States, in the West Indies, Central
America, and the warmer portions of South America.
These three kinds of ticks are similar to the wood
ticks in appearance but differ in their development.
The seed ticks and nymphs do not drop to the ground
to molt. Thus they remain on their hosts continu-
ously for 18 to 30 days and are therefore more easily.
controlled by systematic dipping or other periodic
treatment. The tropical horse tick fs found mainly
in,the external ears of horses and mules. The winter
tick and cattle ticks attach to various parts of
either horses or cattle. These ticks do not attach
themselves to man or carry any human diseases, but
cattle ticks are the carriers of Texas fever of

Individual animals may be freed of these
ticks by the application of an insecticide. When
only a few animals are to be treated, a derris or
cube dip prepared according to the method recom-
mended for use against wood ticks may be used, ex-
cept that it should contain 7 ounces of derris or
cube powder per gallon. It is applied as a wash
every 2 weeks. When large numbers of animals are
to be treated a dipping vat should be constructed
and the animals dipped in an arsenical solution.
One of the commercial concentrated arsenical dips
prepared and sold for the control of cattle ticks
may be diluted and used according to the directions
received with the material. The arsenical content
of the diluted dip should be 0.18 to 0.19 percent
arsenious oxide.

Circular 12 Ticks


The spinose ear tick, Ornithocoros men.-nini
(Duges), (fig. 12), attaches itself deep in the
ears of most of the
larger animals and oc-
casionally in those of
man. dhen the larvae
r have completed engorze-
ment they remain at-
I f tached until they molt,
and the nymphs reattach
~JE themselves in the ear
of the same animal. The
period of attachment
j ranges from 1 to 7 months.
r,4hen the nymphs have comi-
Spleted feeding they drop
to the ground, where they
molt to adults. The adults
never feed, but mate and
lay eggs v.ithout reattach-
Fig. 12- The spinose ear ing.
tick, Ornithodoros megnini
(Dug~s). Nymph. This tick is a
troublesome pest of horses
and mules. It affects
their condition and makes
them hard to bridle. A single tick in a man's ear
may produce severe pain and other discomfort. In-
festations of the ears of men sleeping on the ground
during maneuvers are not infrequent.

Small ticks are not easily seen or removed
from the ears of man without suitable equipment.
Usually all that is necessary in such cases is to
remove them with forceps. Camps should not be lo-
cated close to corrals or other places where live-
stock concentrate. Ticks in the ears of animals
should be killed by injecting a mixture of 2 parts of
pine tar to 1 part of cottonseed oil into the ears

21 Circular 12 Ticks

with a syringe. This iixture will kill the ticks
present and prevent reinfestation for about 30 days.
It is harmless to the skin inside the ears, but
should not be allowed to remain in contact with the
-ace or other parts covered with hair, where it may
cause loss of hair.

-i -- -r J A '_- /T jI~"J
*-"-' j... -j; i ]S

Pishbpp, 7. 0. Ticks and the role they play in
the transmission of diseases. Snith-
sonian Report for 1933, PP. 389-406.
*iashinf'ton, D. C. (Pub. 3276).

*ishopp, V. C. The brovwn dog tick, with sugges-
tions for its control. U. S. Department
of A,-ri., Bur. Ent. & P. q. Cir. 2-292.
Revised' July 1939. '/ashington, D. C.



.. 3., and 0mith, C. N. The A.aerican dog
tick, eastern carrier of Rocky Mountain
spotted fever. U. 3. Dept. Agri. Cir.
478. April 1938. Washington, D. C.

F. C., and S:2ith, C, N. Combating the
American dog tick, carrier of Rocky 11oun-
tain spotted fever in tne Central and
Eastern States. U. S. Dept. Agri., Bur.
ant. & P. -. Cir. E-454. October 1938.
dashington, D. C.

Cooley, R. A. The Rocky fountain wood tick. Mon-
tana Agr. Expt. Sta. lull. 268. 1932.

ZllenberFer, J. P., and Chapin, R. i. Cattle-fever
ticks and methods of eradication. U. S.
Dept. A-ri. farmers' Bulletin 1057.
Jan. 1932. 'Vashington, D. C.

Hers, 7i. L. Medical _ntomology, 582 pp.
MTacrmillan Company, New York.


Circular 12 Ticks

Times, M.

The spinose ear tick. U. S. Dept.
Agri. Farmers' Bulletin 980. MIIay 1918.
Washington, D. C.

Patton. W. S., and Evans, A. -'I1. Insects, Ticks,
l.ites, and Venomous Animals of Veteri-
nary and Liedical Importance. Pt. 1
MIedical, 786 pp. 1929.


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