Groundhog ticks are widespread throughout much of southern Ontario and Quebec as well as in other southerly locations in eastern Canada where they make their homes in the dens of their hosts as far west as Manitoba. They look remarkably like blacklegged ticks in terms of size and other physical characteristics, so much so that the average person has difficulty telling them apart. One hint that you may be looking at a groundhog tick and not a blacklegged tick is that peak activity for adult groundhog ticks is in mid-summer while adult blacklegged ticks are most active in spring and fall.
Groundhog ticks aren't typically associated with Lyme disease in humans although at least one study in Canada has shown the tick can be a carrier of Lyme bacteria. The greatest risk to humans from a groundhog tick bite is Powassan encephalitis. This tick is a primary carrier of Powassan virus in Canada and although encephalitis caused by a Powassan infection is rare here, the condition can lead to a dangerous illness sometimes resulting in death. Research has shown that close to 25% of groundhogs (aka woodchucks) in Ontario are infected with this virus.
The good news is that this tick rarely bites humans. It has a strong preference for feeding on groundhogs, but is also known to target several species of small and medium-sized mammals such as cats, dogs, fishers, foxes, martens, minks, porcupines, raccoons, skunks, and weasels. It has also been found feeding on several different bird species and can live for more than a year without feeding.
Diseases carried: Powassan virus.
Where found: Every province from Manitoba to Newfoundland.
Photo of a groundhog tick (Ixodes cookei) courtesy of the US Centers for Disease Control and Prevention.