Rocky Mountain Wood Tick

Dermacentor andersoni Stiles
Pest Stats
Color: Brown, becoming grayish when engorged
Legs: Larvae have 6 legs, nymphs and adults have 8 legs
Shape: Oval, flattened
Size: 1/8” (3.2 mm) un-engorged; 5/8” (16.5mm) engorged
Antennae: No
Region: Rocky Mountain states

The Rocky Mountain wood tick — also known more simply as the wood tick — gets its name from its primary distribution in the Rocky Mountain states and its preferred habitat of wooded areas.

Habits

Similar to the lone star tick, the Rocky Mountain wood tick is considered a three-host tick because each feeding stage requires a different host. This tick species becomes active with the first warm days of spring, usually feeding from mid-March to mid-July — when humans are most susceptible to wood tick-related diseases. Larvae and nymphs feed mainly on rodents such as voles, chipmunks and squirrels. Adults prefer to feed on medium to large animal hosts including sheep, deer and humans.



Habitat

Rocky Mountain wood ticks are usually found in wooded areas with low-growing vegetation, open grasslands and around trails. This tick is found at higher densities at lower elevation. This environment helps them easily attach to a passing host that brushes against the vegetation. Nymphs and adults overwinter in ground debris.



Threats

The Rocky Mountain wood tick is a primary vector of Rocky Mountain spotted fever, a severe infectious disease with a mortality rate of more than 20 percent. A tick needs to be attached for more than two hours before the disease is transmitted, so early detection is key. The main symptom is a full body rash that develops 2-5 days after the bite.

This tick species can also transmit Colorado tick fever and tularemia, and is known to cause tick paralysis when it feeds for at least 5-6 days.