American Dog Tick in SD
American Dog Tick in SD
Mike Catangui, Ph.D. Associate Professor, South Dakota State University
Posted on April 19, 2000. Last updated on May 1, 2003.
(Click on thumbnails for bigger images)
American dog ticks or wood ticks (Dermacentor
variabilis) are the most commonly
encountered ticks in South Dakota. Two images above compare males and
females of the American dog tick with a male deer tick. Notice that unfed wood ticks
are about twice the size of an unfed adult deer tick.
In South Dakota, most of the complaints of infestation
in humans due to wood ticks
occur in early spring. And based on our surveys, all of the ticks encountered at
this
time are adults. Most probably, these adult ticks spent the winter in or close to
burrows
of small rodents. It is known that adult wood ticks can survive for more than 2
years
without feeding. Adult wood ticks may infest dogs, horses, humans, and many other
warm-blooded animals.
After feeding and mating on the host (e.g., on a dog)
for about 2 weeks, the engorged
adult female tick drops to the ground then lay eggs in cracks and crevices. In
homes,
tick eggs have even been found underneath flower pots. A single female can lay up to
6,000 eggs.
Larvae hatching from eggs very rarely infest
humans. They prefer small rodents.
Engorged larvae drop to the ground, molt into nymphs, then climb to small animal
hosts. Engorged nymphs drop to the soil then turn into adults, which will then seek
bigger hosts including humans. Thus, the stages of tick development are eggs, larva,
nymph, and adult.
Under favorable weather and abundant hosts, wood ticks
can complete their
development from eggs to adults in about 3 months. However, if hosts are not
present,
development could be extended for over 2 years.
American dog ticks are capable of transmitting the
microorganisms that cause
tularemia (rabbit fever) and
Rocky Mountain Spotted Fever in humans.
A tick species related to the American dog tick called the Rocky Mountain wood
tick
(Dermacentor andersoni) is capable of transmitting the microorganism that
cause
Colorado
tick fever, tularemia, Rocky Mountain Spotted Fever, among others. The
Rocky Mountain wood tick is known to occur in the higher elevations of western
SD.
Crawling Tick Video