Our cottage is on an island, and the only mammals there are mice and voles. What is the probability that ticks are also on the island?—Carolyn Beaton, via email
It’s not high. “But it’s not zero,” says Robbin Lindsay, a research scientist with the Public Health Agency of Canada. Black-legged ticks—the ones that carry Lyme disease, and the ones we assume you’re concerned about—do feed on birds and, therefore, could be introduced practically anywhere those birds go. “But it’s rare that ticks would become established in a place with no white-tailed deer,” says Lindsay. While tick larvae and nymphs use mice and voles as hosts, adult ticks generally prefer deer. In places without any deer, tick numbers typically either crash completely, or remain low. “Adults just don’t seem to feed on small mammals,” says Lindsay. “They don’t like ’em.”
Or maybe it’s all about location. Larvae and nymphs hang out on vegetation low to the ground. Adult ticks, on the other hand, choose plants about three feet off the ground, or chest-height on a white-tailed deer. (Ticks can’t jump or fly. They can only wait in the “questing” position—with their front legs outstretched—to grab on to whatever walks by.) It’s like the bar scene on all-ages night, says Lindsay. “The adults are on the top floor, and the kids stay below.”
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