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 American Dog Tick
Common
Name:American dog
tick
Scientific Name: Dermacentor variabilis
Introduction.
This
tick’s common
name comes from the
fact that it is only
found
In North America and
that domestic dogs are
the favorite host of
the adults. Although
not a structural pest,
it is commonly found
on dogs and readily
attacks humans. It is
of medical importance
because it vectors the
causal organisms of
Rocky Mountain spotted
fever and tularemia,
and also causes tick
paralysis. It is found
throughout the United
States except for the
area of the Rocky Mountains,
and in Canada and Mexico.
 Recognition.
Unengorged adult females
are about 3/16 inch
long, while males are
slightly smaller – about
1/8 inch long. Engorged
females are about 5/8
inch long, and 3/8 inch
wide. American dog ticks
have oval, flat bodies
and are colored brown
with whitish to grayish
markings. Female ticks
have a marbled cape-like
pattern on the upper
front part of the body
while males have a marbled
pattern over the entire
upper body surface.
Similar Ticks. The brown dog tick or
so-called kennel tick
(Thipicephalus sanguineus)
is brown with black
markings and is less
commonly encountered
than the American dog
tick. Occasionally,
dogs become infested
with brown dog ticks
while boarding in kennels
with previously infested
dogs.
Biology. The
engorged female tick
drops off the host animal
and seeks a sheltered
place to lay her eggs.
Over 14 to 32 days she
lays egg masses totaling
4,000 to 6,500 yellowish-brown
eggs, and then dies.
Egg hatch usually occurs
in 36 to 57 days. Unfed
6-legged larvae actively
crawl about seeking
a host. They can survive
for up to 540 days unfed.
Larvae require about
4 days (range 3 to 13
days) to become engorged,
then drop off the host
and seek shelter for
molting purposes. Usually
10+ days (range 6 to
247 days) are required
from drop to nymphal
emergence. Unfed nymphs
(8-legged) actively
crawl about seeking
a host. Engorgement
usually requires about
6 days (range 3 to 12)
but they can survive
for up to 584 days unfed.
After feeding, they
drop off the host and
seek shelter in which
to molt. Molting usually
requires about 24 days
(range 24 to 291). Adults
crawl up on grass or
other low vegetation
and wait for a host
to pass. After both
sexes have fed, females
are completely engorged
in about 11 days (range
5 to 27 days), mating
occurs on the host.
Males continue to feed
but females drop off
to lay their eggs. Females
require a 3 to 58 day
preovipostion or waiting
period before egg laying
begins. Unfed adults
can survive for about
2 to 3 years (up to
1,053 days). The entire
life cycle (egg to egg)
requires from 3 months
to more than one year,
and both larvae and
nymphs can overwinter.
In the northern states,
a 2-year life cycle
may be more common.
American dog ticks are
the primary vector of
Rocky Mountain spotted
fever in the eastern
United States, which
they transmit from small
animals. This is a severe,
acute, infectious disease
of the small peripheral
blood vessels caused
by a rickettsial organism
whose characteristic
symptom is a rash which
develops in 2 to 5 days,
starting with the wrists
and ankles, and then
spreads all over the
body. Mortality in humans
is 20% or more. Fortunately,
attachment for 2 hours
or more is required
for transmission.
These ticks also transmit
tularemia which is caused
by a bacillus and is
transmitted from rabbits,
meadow voles, ground
squirrels, sheep, beavers,
coyotes, and various
game birds. Symptoms
include chills and fever,
prostration, an ulcer
at the tick-bit site,
and tender, swollen
lymph nodes.
In addition, American
dog ticks can cause
tick paralysis when
they attach on the back
of the neck or at the
base of the skull and
feed for at least 5
to 6 days. Paralytic
symptoms usually start
in the extremities and
become evident as unsteadiness
and loss of reflex actions.
If the tick is not removed,
death may result from
respiratory failure;
children are particularly
susceptible. If the
tick is removed, recovery
is rapid and usually
within 24 to 72 hours.
De-ticking dogs is an
important way that Rocky
Mountain spotted fever
is spread. Handpicking
is dangerous because
infected tick secretions
on the hands can be
transmitted via contact
with eyes, mucous membranes,
etc. Use forceps or
a scraping device for
removal.
 Habits. The American
dog tick does not survive
well indoors. If found
indoors, It was probably
carried in on a dog
and dropped off when
fully engorged to seek
a suitable place for
egg laying.
This is a 3-host tick,
with each stage requiring
a different host. Both
larvae and nymphs actively
crawl about seeking
a small mammalian host,
primarily rodents. Hosts
include the deer mouse,
meadow vole, cottontail
rabbit, muskrat, Norway
rat, squirrel, and cat.
Adults crawl up grass
or other low vegetation,
cling to it with their
3rd pair of legs, and
wave their other legs
about ready to grasp
onto any passing host.
This is called their
“waiting position.”
They prefer larger mammals
as hosts and these include
the preferred dog and
others such as man,
cattle, opossum, coyote,
hog, horse, raccoon,
wild cat, squirrel,
sheep, skunk, deer,
fox, domestic cat, mule,
rabbit, Norway rat,
ground squirrel, donkey/burro,
weasel, and groundhog.
American dog ticks are
attracted by the scent
of animals and are therefore,
most numerous along
roads, paths and trails.
The concentration is
further increased along
such travel routes by
the dropping of engorged
ticks from their host
animal.
Larval and nymphal activity
usually starts about
the end of March, representing
those which overwintered,
and continues to mid-July.
Nymphal activity predominates
from June to early September.
Adults become active
about mid-April, peak
in June, and decline
until mid-September.
Control. Reducing the likelihood
of being fed upon by
American dog ticks can
be separated into two
recommendations to the
public and two steps
best left to a Rottler
pest management professional:
Cultural Control
& Preventative Measures.
1. Personal protection:
Keep trouser legs tucked
into socks or boots,
shirts tucked in, and
clothes buttoned. Avoid
sitting on logs, stumps,
or the ground in brushy
areas. Periodically
inspect clothing and
the body for ticks to
remove them before they
become attached. If
a tick is found attached,
remove it with a slow,
steady pull that will
not break off the mouthparts
and leave them in the
skin. It is best to
use fine-tip forceps
whose tips are placed
on or just behind the
mouth parts. If a scraping
device (e.g., clean
putty knife, ruler,
etc.) is used, draw the device firmly over the skin and against the head of the tick
until it is removed.
Do not put pressure
on the tick’s abdomen
or liquids from the
tick’s body may be forced
into the wound. Be sure
to clean the attach-
ment area with rubbing
alcohol or other disinfectant.
Liberal use of proven
tick repellents is helpful,
including application
to clothing.
2. Habitat modification.
Keep the grass cut to
3 inches or less; this
also reduces rodent
habitat. Trim back vegetation
along trails, paths,
and yard edges. Remove
debris and ground cover
to discourage rodents.
Professional
Measures.
1.
Pesticide application:
In heavily infested
areas a Rottler pest
management specialist
can make an application
of an appropriately
labeled residual pesticide.
The technician will
concentrate on the areas
most likely to harbor
ticks such as along
paths, trails, property
lines, fence rows and
the yard- woods interface.
The first application
should be in the early
spring to reduce the
larvae and nymphs that
overwintered
2. Removal of hosts:
The reduction or elimination
of rodents in the area
immediately surrounding
the house is helpful.
This can be accomplished
with the use of rodenticides
and/or rodent traps
placed in tamper-resistant
stations
and secure areas inaccessible
to children and pets.
Locations
Serving the St. Louis Metropolitan area since 1956, including
Arnold, Ballwin, Chesterfield, Crestwood, Creve Coeur, Des Peres,
Fenton, Florissant, Kirkwood, Maryland Heights, Overland, St.
Charles, Webster Groves, Wentzville and surrounding areas.
In Illinois: Belleville, Collinsville, Edwardsville, Columbia,
Madison, Waterloo, O’Fallon, Granite City, Alton, St. Clair, Monroe
and surrounding areas.
Columbia & Jefferson City, MO and surrounding areas. |
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