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INTRODUCTION.
This tick gets its common name from its overall reddish brown color and that it is common
on dogs. Although the brown dog tick is the species most commonly encountered indoors, it
rarely attacks man. This tick is found throughout the United States and the world.
RECOGNITION.
Unengorged adults are about 1/8" (3 mm) long, but enlarge up to about 1/2" (12
mm) long when engorged with blood. Body flattened dorsoventrally (top to bottom). Reddish
brown in color, but when engorged, engorged parts of body change to grey-blue or olive
color. Male with tiny pits scattered over the back. Scutum (dorsal shield just behind
mouthparts) present which covers male's entire back but only front part of female's back.
Eyes on margin of scutum. Capitulum (mouthparts and their base) visible from above; basis
capituli (base for mouthparts) laterally producedlanqular, not straight; 2nd segment of
palpi about as long as wide. Abdominal festoons (rectangular areas divided by grooves
along posterior margin) present; anal groove present, posterior to anus.
SIMILAR GROUPS.
American dog tick (Dermacentor variabilis) and other Dermacentor
species have sides of basis capituli (base for mouthparts) straight, not laterally
produced/angular, although base may be angular laterally, and abdomen with 1 1 festoons
(rectangular areas divided by grooves) along posterior margins.
Lone star tick (Amblyomma americanum) has 2nd segment of palpi twice
as long as wide, female with pale markings near hind end of scutum (dorsal shield).
Cattle tick (Boophilus annulatus) lacks anal groove and festoons.
Bird and rabbit ticks (Haemaphysalis spp.) lack eyes, anal groove
behind anus, festoons present, 2nd segment of palpi laterally produced.
Ixodes spp. lack eyes, have anal groove in front of anus, lack
festoons.
Soft ticks (Argas, Omithodoros, etc.) lack a scutum (dorsal shield),
capitulum (mouthparts and their base) ventral, not visible from above.
BIOLOGY.
The engorged female drops off the host dog and seeks a sheltered spot in which to lay her
mass of typically 1,000-3,000 tiny, dark brown eggs. Since she has a tendency to crawl
upwards, eggs are often deposited in cracks and crevices near wall hangings, ceiling, or
roofs. She dies afterwards and the eggs hatch in 19-60 days into minute, 6-legged larvae
or seed ticks. They crawl down the walls and attach to a dog as soon as possible but can
survive for 8 months without food or water. After engorging for 3-6 days, during which
they become globular, blue, and about 1/16" (2 mm) in diameter, they drop off and
seek a sheltered place in which to molt. In 6-23 days they become 8- legged, reddish brown
nymphs, which can survive for about 3 months without food or water. They again attach and
engorge for 4-9 days, becoming oval, about 1/8" (3 mm) wide, and dark gray. The
nymphs then drop off, hide, and usually molt in 12-19 days into adults. Although the
adults attach to a dog at the first opportunity, they can survive 18 months before
attachment. Once attached, they engorge for 6-50 days, mate, and the females drop off to
lay eggs and repeat the cycle. Under favorable conditions, the cycle can be completed in
about 2 months but there are usually only 2 generations per year in the north and 4 in the
south.
Although they rarely attack humans, brown dog ticks can serve as
vectors for Rocky Mountain spotted fever and several other disease organisms.
HABITS.
The brown dog tick does not do well outdoors in the woods in the United States. They
prefer warm, dry conditions where dogs live. They do not travel far after engorgement and
dropping off the host. They typically move upward, a behavior which usually promotes host
encounters.
Brown dog ticks may attach themselves anywhere on a dog. The adults
typically attach on the ears and between the toes, but the larvae (seed ticks) and nymphs
typically attach on the back.
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