What a colder winter means for Maine ticks

By Elizabeth Walztoni, Bangor Daily News Staff

After another year of record-breaking Lyme disease case reports, Mainers may be hoping a colder, drier winter is putting a dent in tick populations. 

Warm, wet winters help disease-carrying ticks, which have been spreading farther into Maine in recent years, survive and reproduce more.

But one cold season might not be enough to slow them down, according to one of the state’s experts.

“Ticks are surprisingly resilient to cold weather,” said Griffin Dill, coordinator of the University of Maine Cooperative Extension’s Tick Lab. 

That’s because they can spend the winter hiding beneath leaf litter and snow cover that insulates them from harsh conditions, according to Dill. A colder winter might delay their spring activities slightly, but isn’t likely to put a noticeable dent in their population. 

Researchers found in 2021 that some ticks could survive temperatures seven degrees below zero. 

National Weather Service data shows January temperatures in the Bangor area averaged about 18 degrees, which was five degrees colder than in 2024 and nine degrees colder than the year before that. It saw about 1.5 inches of precipitation, half as much as last year and more than three times as much as in 2023. 

Tick-borne disease cases rose in those years. Maine ticks were known to sicken more than 3,000 people in 2023 and 4,500 in 2024. Several died. This data only includes people who identified and reported the diseases, scientists have said, meaning it likely doesn’t cover all cases.

Ticks are also a problem for the state’s moose population. Another species, the winter tick, is the leading cause of death in young calves and also affects reproduction in adults, according to the state Department of Inland Fisheries and Wildlife.

Ticks, including ones that transmit diseases to people, can also resume activity during warmer periods in the winter months – so be careful on cold weather hikes, too.