Health: Cold Weather Gives No Respite From Ticks

By: Alan Pollock

Topics: Ticks

Covered in ice, this tick is alive and will be actively searching for a host when the temperature rises above freezing. COURTESY TICKENCOUNTER.ORG

With this week’s spring-like temperatures, people are peeling off layers of clothing and venturing outdoors for some fresh air. And on the bike paths, in the yard and on conservation trails, they’re not alone. Unfazed by the deep freeze last week, ticks are once again active, looking for a mid-winter blood meal.

“People think, with that cold freeze, it must be safe out there,” said county entomologist Larry Dapsis, the deer tick project coordinator for the Cape Cod Cooperative Extension. “And that is the worst conclusion that people can draw.”

As if their saw-shaped mouth parts and thirst for blood weren’t enough, ticks have another devilish adaptation that allows them to be active even in the deep of winter.

“They’ve been on this planet for 120 million years. They lived through the ice age,” so the coldest winters in New England don’t thwart them, Dapsis said. Ticks’ bodies contain glycerol, which is chemically very similar to ethylene glycol, or antifreeze. Ticks can be covered in ice or buried in snow, but when temperatures rise above freezing, they become active again.

“The only thing that reduces exposure risk is if you have a heavy snow pack,” Dapsis said. “They don’t crawl up through the snow.”

The same preventive measures needed in the warmer months are necessary in the winter, he said.

“Permethrin-treated clothing and footwear, hands down, is the most effective tool in the box,” Dapsis said. Available at local garden centers and other retailers, permethrin is designed to be sprayed on clothing and shoes – not directly on skin – and repels or kills ticks and other crawling bugs. The chemical continues to be effective through five or six washings, and is safe to use even on children’s clothing.

After spending time outdoors, it’s wise to do a tick check, which is why wearing light-colored clothing is the best option. Because ticks can be almost impossible to see, the safest bet is to put pants and socks in a hot dryer for 20 minutes after outdoor activity, Dapsis said.

Reducing the likelihood of tick bites isn’t just about controlling the spread of Lyme disease, he said. Last year, of all the ticks tested on Cape Cod, 13 percent were infected with more than one pathogen, meaning the ticks could transmit as many as four diseases through one bite.

“The medical community and people really need to take note of that,” Dapsis said.

The prevalence of ticks in different stages of their life cycles varies by time of year. The late spring and summer are arguably the most dangerous times for deer ticks, the main vector for Lyme disease, because, as nymphs, they are small and extremely difficult to see. A deer tick nymph is about the size of a poppy seed.

In a video series posted at, Dapsis tells all about ticks, including how to safely remove them. Thanks to a continuing subsidy from Cape Cod Health Care, ticks can be sent away for testing for as little as $15 through the website The lab provides a report within three days, and people bitten by ticks can share that information with their physician.

The prevalence of ticks on Cape Cod also varies by area.

“The situation from Brewster on out is a higher risk than what we see in the data on the Upper Cape,” Dapsis said. The most likely explanation is the Lower Cape’s micro-climate, which tends to be slightly more humid than inland locales, creating more favorable conditions for ticks, he said. In some parts of the Lower Cape, the micro-climate is very similar to that on Nantucket and Martha’s Vineyard, “which is the worst in the universe,” he said.

The number of ticks can fluctuate year to year, probably because of variations in rainfall and moisture. But the annual difference isn’t that significant, Dapsis said.

“The harsh reality is that, even in a ‘good’ tick year on Cape Cod, it’s a bad tick year, because the stakes are so high,” he said. A single tick bite can change a person’s life forever, Dapsis noted.