Rocky Mountain Wood Ticks

Habits

The Rocky Mountain wood tick is considered a three-host tick because each feeding stage (larva, nymph, and adult) 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 temperatures increase and the air becomes more dry. Rocky Mountain wood ticks typically crawl up low vegetation and wait for an appropriate host to pass. 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. Adults are active on the ground during sunny days, climbing up and down vegetation along trails. Adult female Rocky Mountain wood ticks will insert their mouthparts into the host and feed until fully engorged, while male Rocky Mountain wood ticks feed for a shorter period of time.

Adult Rocky Mountain wood ticks can survive for more than a year unfed. The full life cycle of a Rocky Mountain wood tick requires one to three years outdoors depending on host availability.

Threats & Diseases

The Rocky Mountain wood tick is a primary vector of Rocky Mountain spotted fever, which they contract and transmit after feeding on small animals, primarily rodents. Rocky Mountain spotted fever is a severe infectious disease with a mortality rate of more than 20 percent if left untreated. The main symptom of this infectious disease is a rash that develops in 2-5 days, starting with the wrists and ankles and then spreading to the rest of the body. A wood tick needs to be attached for more than two hours before the disease is transmitted, so early detection is key.

Rocky Mountain wood ticks are also vectors for Colorado tick fever, a viral disease of short duration and low mortality. The disease is characterized by sudden onset saddleback fever (fever disappearing in 1-3 days in middle of illness only to later return), headache, muscular pain, and reduction of white corpuscles in blood. In contrast to tickborne diseases such as Lyme disease, there is typically no accompanying rash. The disease is more common in adult males, but also occurs in women and children.

This tick species can also transmit tularemia, typically transmitted from rabbits and rodents. Symptoms of tularemia include chills and fever, prostration, and ulcer at the site of the tick bite, as well as tender, swollen lymph nodes.

Additionally, Rocky Mountain wood tick bites can cause tick paralysis when they feed for at least 5-6 days. Paralytic symptoms usually start in the extremities and become evident as unsteadiness and loss of reflex actions. If the tick is not removed, death could result from respiratory failure. Children are particularly susceptible to this. However, if the tick is properly removed, recovery is rapid – usually within 24-72 hours.