American Dog Ticks
Order: Acarina
Family: Ixodidae
Scientific Name: Dermacentor variabilis (Say)
The American dog tick attacks
man and domestic animals. It
is an important vector of several disease organisms.
This hard tick (Ixodidae family) is usually found outside and transported
into structures on dogs. Often
called a “wood tick,” this tick should not be confused with the brown
dog tick. Their habits differ
– only the brown dog tick can lay eggs indoors.
Description
The adult male is flattened, 1/8- to 3/16-inch long and has a pale whitish or yellowish marking over most of its body. The male does not increase greatly in size upon feeding.
Before feeding, the female resembles the male generally in size, shape and color. However, the marking only covers 1/3 of the body. As the female feeds and enlarges, she increases in size to about ˝-inch in length (12.8 mm) and 3/8-inch wide (9 mm). When fully engorged, she is bluish gray.
The tick has four stages: egg, larva, nymph, and adult. The larvae have six legs. Both the larva and nymph are very small and generally not seen since they feed on a variety of small mammals including mice, rats, shrews, and small birds. The adults feed on a variety of larger mammals, including man. These ticks can spread the rocky mountain spotted fever organism to man.
Life Cycle
After feeding and then mating, the engorged female drops from the host, seeking protected locations close to the ground around clumps of grass. Approximately 6 to 58 days later, she begins laying eggs. Over a two-to-four week period, 4,000 to 6,500 eggs are laid, usually in masses of 800 or more. Afterwards, the female dies. Adult tick activity begins in April, increases until June or July and almost ceases in August or September.
The eggs normally hatch in 36 to 57 days, although incubation periods may extend over several months in cooler temperatures. Larval and nymphal ticks actively seek small rodent hosts and do not assume the waiting position typical of adults. Both stages can live for more than a year before feeding. Larvae feed about 4 days on the host animal, while nymphs require 3 to 11 days. Molting periods for larva to nymph and nymph to adult are 10 to 247 days and 24 to 291 days, respectively.
Under favorable conditions,
the entire life cycle of the American dog tick requires from 4 months
to more than a year. There
is one generation per year in the northern areas and two to three generations
per year in the South.
Control
Control of these ticks
primarily involves homeowners inspecting their animals for these ticks
and removing them. Since
eggs will not hatch in structures, no pesticide treatment indoors is necessary.
(Courtesy of the National Pest Control Association.)