Common Name: Tick – Dermacentor ticks

Other Names: Wood Ticks, American Dog Tick, Pacific Coast Tick, Rocky Mountain Wood Tick

Origin: These ticks are native to North America.

Biology: Hard ticks in general have a two year life cycle, with eggs hatching to the 6-legged larva in the spring, these progressing to the second instar nymph stage which overwinters, and these progressing the following year to the adult tick.  There is usually a single blood meal at each stage, with the tick remaining attached for several days to over a week.  After fertilization by the male, and a blood meal, the female hard tick produces a single batch of up to several thousand eggs, and then she dies.  These eggs are usually placed into a secluded crevice of some sort, and this may be within a structure.  The engorged, gravid female bloats to many times her original size.  Ticks in the genus Dermacentor are potential vectors of most of the diseases spread by ticks, including Rocky Mountain Spotted Fever, Colorado Tick Fever, Encephalitis, Tick Paralysis, Q Fever, and Tularemia.  These ticks feed commonly on dogs, wild animals, and on humans, and are often the most common ticks found infesting and biting humans.

Identification: The Dermacentor ticks are very similar to the brown dog tick – genus Rhipicephalus.  Adults are about 3 mm long, flattened top to bottom, and are much wider at the posterior end than the front.  There are tiny pits scattered over the top of the body, and the color ranges from grayish brown to dark reddish brown.  With high magnification several other key characters distinguish this group.  By the anal opening on the underside of the abdomen there is no small “anal groove” just behind the anus which is present in Rhipicephalus ticks. In addition, the body plate directly behind the mouthparts, the “basis capituli,” does not have pointed expansions on each side, but instead the sides of this plate are parallel.

Characteristics Important in Control: Tick control begins with prevention, by helping people understand what ticks look like, how to inspect for them, and how to remove them when found on clothing or the body.  The use of repellents, light colored clothing, and frequent inspection when in tick infested habitats are important. Pets should be carefully inspected as well after activity in potential tick habitat.  For tick infestations within a structure careful applications of a residual pyrethroid to cracks and crevices that may harbor the ticks or their egg masses may be needed, and outdoors applications to turf and foliage around the perimeter of a property will kill ticks that are close to this urban environment.