Lewis, Kenneth R.

Texas A&M University

TICKS ATTACKING
HUMANS AND PETS
Kenneth R. Lewis
Area Extension Entomologist
Texas A&M University Agricultural
Research and Extension Center at Overton
L·1403
A
Ticks are grouped into two families: 1) the
"hard ticks" (Ixodidae), which have a hard, smooth
skin and an apparent head; and 2) the "soft ticks"
(Argasidae), which have a tough, leathery, pitted
skin and no distinguishable head. Although both
groups contain species that attack humans and ani-
mals, some hard ticks are more of a problem in
Texas and will be discussed in greater detail.
Life Cycle
Ticks have four developmental stages - egg,
six-legged larva, eight-legged nymph and adult
(Fig. 1). Hard ticks usually mate on the host animal.
The female then drops to the ground and deposits
from 3,000 to 6,000 eggs, which hatch into larvae or
"seed ticks." Larvae climb nearby vegetation where
they collect in large numbers while waiting for small
rodents or other vertebrates to pass within reach.
After a blood meal on the host, the engorged larvae
drop to the ground, shed their skins (molt) and
NYMPH
FEMALE
LARVA
MALE
o t Texans, at one time or another, will ex-
perienc the aggravation of tick bites. Knowledge of
tick and th ir habitats, as well as methods of tick
control, can help you avoid this problem.
Ticks are parasites of warm-blooded animals.
Their bites are not only annoying, but can be pain-
ful, causing localized skin inflammation and infec-
tion and pos ible introduction of disease-causing
microorganism into host animals.
Ticks are not insects, but are closely related to
mites, piders and scorpions. Adult ticks have eight
legs, while adult insects have only six. Also, the
tick's body is fu ed into a single region, instead of
having the head, thoracic and abdominal regions
typical of insects.
EGG MASS
Figure 1. Typical d v lopmental stages for
tick of primary Importanc In Texa . Figure 2. Male (A) and f male (8) American dog ticks
Texas Agricultural Extension Service • The Texas A&M University System • Daniel C. Pfannstiel, Director • College Station, Texa
Figure 4. Female lone star tick
Disease Transmission
When feeding, the tick makes a small incision
in the skin of the host and inserts barbed piercing
mouth'parts to remove the blood. Most species
the American dog tick (Dermacentor variabilis), the
brown dog tick (Rhipicephalus sanguineus) and the
lone star tick (Amblyomma americanum).
Adult American dog ticks are chestnut brown
with white spots or streaks on their backs (Fig. 2).
Unfed adults are about lis-inch long. Engorged
females become slate gray and may expand to a
length of1h inch. Larvae and nymphs feed mostly on
small rodents, while adults feed on dogs, cattle,
humans and other animals. These ticks are widely
distributed over the eastern two-thirds of Texas,
but are most abundant in coastal and other humid
areas. They are attracted by the scent ofanimals, so
are most often encountered near roads, paths, trails
and recreational areas. Although present the year
round, American dog ticks are usually most numer-
ous in the spring.
Adult brown dog ticks are reddish-brown (Fig.
3). Unfed adults are l/s_ to 3/16-inch long, and en-
gorged females are about V2-inch long. They feed
almost exclusively on dogs, where they attach to the
ears and between the toes. They rarely attack man
or other animals. Although widely distributed in
Texas, these ticks prefer areas near human habita-
tion or dog kennels. Inside the home, the ticks hide
behind baseboards, window casings, window cur-
tains, ceiling and picture moldings, bookcases and
cabinets, as well as inside upholstered furniture and
under the edges of rugs. Outdoors, they hide near
building foundations, in crevices between porch
floorings and sidings and beneath porches.
Adult lone star ticks are various shades of
brown or tan (Fig. 4). Females have a single
silvery-white spot on their backs and males have
scattered white spots. Unfed adults are about
lis-inch long, but after feeding, females may be
lh-inch long. Larvae and nymphs parasitize small
wild animals, birds and rodents, while adults feed
on larger animals. All three stages will bite humans.
These ticks live in wooded and brushy areas of
Texas, and are most numerous in underbrush along
creeks and river bottoms and near animal resting
places. Lone star ticks are present throughout the
. year, but peak.adult and nymphal populations occur
in April or May and again in July or August, while
peak larval activity is reached in mid-June or July.
~.~
'J.
Figure 3. Female brown dog tick
Common Species in Texas
The term "wood ticks" is applied to several
species of hard ticks so similar in appearance and
habits that it is difficult to distinguish one from
another. In Texas, the most common of these are
emerge as nymphs. The nymphs locate a host, en-
gorge themselves with blood, drop to the ground,
molt and become adults. Adult ticks seek host ani-
mals and, after engorgement, mate.
Male hard ticks usually mate with one or more
females and then die, although some may live for
several months. Females die soon after depositing
their eggs. The life cycle requires from about 2
months to more than 2 years, depending on the
species.
This life cycle is characteristic of the tick
species which commonly infest humans and pets in
Texas. However, some species feed on only one
host during the life cycle.
Protection from Ticks
traveled by humans and large animals. For a more
complete survey a small, square piece ofwhite flan-
nel cloth can be dragged slowly over low vegetation
beside trails and roads. Waiting ticks will attach
themselve~ to the cloth, and can then be studied to
determine the species and degree of infestation.
Some degree of protection against ticks can be
obtained by keeping clothing buttoned, shirt tails
inside trousers and trouser legs inside tOps of socks.
Do not sit on the ground or on logs in brushy areas.
Persons who must be in areas suspected of
supporting infestations should examine their cloth-
ing, body and hair at least twice daily so that ticks
can be removed promptly.
Brush along trails should be cleared or burned
and weeds and grass in recreation areas should be
cut. In residential areas, closely cut and well-kept
lawns help control both ticks and their small rodent
hosts.
Repellents such as diethyl-m-toluamide, di-
methyl phthalate, dimethyl carbate or ethyl hexan-
diol will protect exposed skin, but will not stop ticks
from crawling under clothing to reach untreated
portions of the body. Applying these materials to
the entire body might prevent tick bites for awhile,
but such extensive treatments often are impractical
and can be hazardous to health. For these reasons,
clothing treatments usually are preferable to skin
treatments. Formulas for preparing clothing treat-
ments include:
Saturate clothing in the mixture. Then wring
out the clothing by hand and hang outdoors until
completely dry. Treatments should provide protec-
tion for about a week unless the clothing gets wet.
Wash and re-treat clothing weekly. Do not treat
undergarments, rayon or nylon fabrics.
cause little or no pain to their hosts at the time of
feeding, but some, such as the lone star tick, cause a
painful wound.
Many disorders and diseases can be traced to
tick bites, including: 1)' dermatosis, or inflamma-
tion, itching and swelling at the site of the bite; 2)
envenomization, or inoculation of toxic fluids; and 3)
exsanguination, or anemia. resulting from the loss of
large amounts of blood because of a severe tick
infestation.
Ticks can transmit diseases by infecting hosts
with microorganisms carried on their mouthparts or
in salivary fluids. American dog ticks are carriers of
Rocky Mountain spotted fever and tularemia (rabbit
fever), and can cause tick paralysis. Lone star ticks
can transmit Rocky Mountain spotted fever,
tularemia and Bullis fever. Brown dog ticks carry
diseases to humans and animals in Africa and the
Mediterranean region, but are not known to trans-
mit human disease in the U.S.
Tick Removal
Because tick movements and bites are seldom
felt, careful and frequent examination for ticks on
the body and clothing is imperative. Early removal
is important since many disease organisms are not
transferred until the tick has fed 2 to 8 hours. Always
remove the tick with its mouthparts intact. Hasty
removal ofan attached tick can break off the mouth-
parts. Mouthparts left in the skin can transmit dis-
ease organisms or cause secondary infections. To
relax tick mouthparts for ,easy removal, touch the
tick with a hot needle or a few drops of camphor,
alcohol, turpentine, kerosene or chloroform. Some-
times the best method is to grasp the tick firmly with
tweezers or fingers and remove it with a slow,
steady pull. Always treat the wound with a germici-
dal agent.
Tick Surveys
Sometimes information is needed about tick
infestation in a given area - the presence or ab-
sence of ticks, tick density or tick species. To obtain
this information, ticks can be removed from host
animals in the area. Clues often can be obtained by
studying past and current land uses. For example, if
the land was once in agricultural production but has
since been abandoned it probably supports a heavy
population of field mice, and, consequently, may be
a tick-infested area. Immature ticks inhabit "mousy
areas," while adults are abundant along trails
1) 1 oz. benzyl
benzoate
3 pints water
3) 5 oz. diethyl-
m-toluamide
3 pints water
2 tbsp. naphtha soap
(not detergent)
2) 1 oz. benzyl
benzoate
3 pints dry-
cleaning fluid
4) 5 oz. diethyl-
m-toluamide
3 pints dry-
cleaning fluid
Tick Control
Ifa tick infestation occurs, treat the home, yard
and p ts at the same time. Examine dogs and cats
frequently for ticks. Control light infestations on
dogs and cats more than 4 weeks old with weekly
applications of dusts containing 5 percent carbaryl
(Sevin®). Rub the dust to the skin and' apply to the
animal's sleeping quarters. Continue treatments for
as long as needed. Heavy infestations on pets should
be handled by a veterinarian.
Light infestations in buildings usually can be
controlled with a household spray containing 0.5
percent diazinon. Also, a spray containing 0.5 per-
cent chlorpyrifos (Dursban®) is registered for con-
trolling brown dog ticks. Apply the insecticides only
as light, spot treatments to areas where ticks are
found or suspected to be hiding. DO aT USE
THESE CHEMICALS FOR TREATING PETS.
Treatment around baseboards, window and door
casings, wall cracks and in pet sleeping quarters is
usually necessary. To control severe infestations in
the home, remove the pet from the house and make
repeated applications of insecticides at 2- to 4-week
intervals. Other insecticides besides those listed are
approved for tick control in buildings. Select a spray
that does not have an objectionable odor and will
not stain paints, wallpaper, tile or rugs.
Tick control in home lawns and other vegetated
areas usually can be obtained with sprays or dusts
containing diazinon or carbaryl. Use 5 percent car-
baryl dust at the rate of 2.5 to 5 pounds per 5,000
square feet of area. If a spray is used, mix 1 quart of
25 percent diazinon emulsifiable concentrate in 96
gallons of water (2 tablespoons per 3 gallon ) and
apply 24 gallons of spray per 1,000 square feet of
area. Give particular attention to spray application
around building foundations and along roadside ,
animal trails and paths used by people.
Insecticide Precautions
The Federal Environlnental Pesticide Control
Act of 1972 (Public Law 92-516) prohibits the appli-
cation ofany pesticide in a manner inconsistent with
its labeling. This means that a pesticide cannot be
used unless it is registered for the specific pest on
the specific host plant or animal, a indicated on the
product label. Consequently, some chemical for-
merly used by homeowners and pesticide
applicators are now prohibited.
The status of insecticide label clearances i sub-
ject to change, and changes may have occurred
since this publication was printed. County Exten-
sion agents and Extension entomologists are
notified as these changes occur.
The insecticide USER always is responsible for
the effects of pesticide residue on his own pre-
mises, as well as problems caused by drift from his
property to that of others. Always read and follow
carefully all instructions on the product label.
The information given herein is for educational purpose
only. Reference to commercial products or trade name is
made with the understanding that no discrimination is in-
tended and no endorsement by the Coop rative Exten ion
Service is implied.
Educational prograrns conducted by the Texas Agricultural Extension Service serve people ofall ages regardless of ocio-econOlnic I els race,
color, x religion or national origin.
Cooperative Ext n ion Work in Agriculture and Home Economics, The Texas A&M University Sy tern and the United Stat Department of
Agriculture coop rating. Distributed in furtherance of the Acts of Congress of May 8, 1914, as amended, and Jun 30, 1914.
30M-5-76, R print E T


Ticks Attacking Humans and Pets.

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Ticks Attacking Humans and Pets.

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