For some of us who live on a dry hillside, the annual tick count is over a dozen so far. About average for my wife and I this time of year, and if we spend any amount of time on our open forest-grassland hillside, we can expect to at least double that by the end of the season.
The ticks don’t want much, only a little of our blood to produce more eggs for another crop of offspring.
According to the literature, the Rocky Mountain Wood Tick (Dermacentor andersoni) is a three-host tick, a new host being sought for each one of its three feedings, which occur over a period of one to three years.
Usually rodents and other small animals (which we have plenty around our place) serve for the first two feedings, and large animals such as deer, cattle, dogs, sheep and humans serve as the host for the last feeding. This tick is most frequently encountered between March and June, usually in open, rocky areas.
I have had quite a range of sizes so far this year, which indicates humans can also serve as host for the mid-size stage as well.
Both sexes wait near the top of grass and low shrubs, readily attaching to passing people or animals that brush against them.
Once on a host, they climb up to the highest spot, usually your head. If they don’t encounter a host, the ticks return to the ground until the next spring. Since we are used to detecting them before they attach, we don’t have to deal with the removal process, which can be tricky to make sure you remove the embedded mouth parts.
If they can attach and start feeding, they reach the size of a swollen raisin, which can take several days.
They drop to the ground and, after several weeks, lay a few thousand eggs and die.
In British Columbia and the western U.S., this tick can cause tick paralysis in mammals, including humans and livestock, which is caused by a neurotoxin in tick saliva.
As described in the literature, it is important to find and remove the ticks to prevent paralysis.
“The first symptoms, usually a numbness in the feet and legs causing difficulty in walking and standing, occur after a female tick has been feeding for about five days. The hands and arms are usually affected next, and there is often partial paralysis of the throat and tongue muscles, resulting in difficulty swallowing and speaking. There is little pain and usually no fever. There is no known antidote for tick paralysis, but complete recovery occurs when the tick is removed if paralysis has not progressed too far. Death may occur if the tick is overlooked. The nature of the toxin, likely secreted by the female during feeding, is not known.”
When we had dogs and cats, we had to constantly groom our pets, especially around the head and neck to search for attached engorged ticks.
Ticks were a constant problem on the experimental ranch I worked on in Columbia.
Jim Hilton is a professional agrologist and forester who has lived and worked in the Cariboo-Chilcotin for the past 40 years. Now retired, Hilton still volunteers his skills with local community forests organizations.