Ticks are resilient arachnids that do not die off entirely once winter arrives. They have evolved sophisticated strategies to survive freezing temperatures, meaning they do not disappear with the first frost. Ticks survive by entering a state of reduced metabolic activity and seeking sheltered microclimates. Their presence and activity are closely linked to temperature fluctuations, meaning they can pose a year-round risk to humans and pets.
How Ticks Survive Cold Temperatures
Ticks employ a combination of behavioral and physiological adaptations to endure prolonged cold periods. Physiologically, they enter a state of dormancy known as diapause, which is a suspension of development and activity. This metabolic slowdown conserves energy and allows them to minimize expenditure while seeking shelter during winter.
Some tick species also exhibit a biochemical defense against freezing. They produce antifreeze-like compounds, such as glycerol, within their body fluids. Glycerol acts as a cryoprotectant, lowering the freezing point of the tick’s internal water and preventing the formation of damaging ice crystals. To further reduce freezing risk, some ticks decrease the overall water content in their bodies. This mechanism allows them to withstand temperatures significantly below freezing, with some black-legged ticks surviving down to approximately 7 degrees Fahrenheit.
Critical Winter Hiding Spots
When temperatures drop, ticks retreat to specific ground-level locations that provide consistent thermal insulation. The most common overwintering habitat is the layer of leaf litter on the forest floor. This decomposing organic material creates a microclimate that is substantially warmer and more stable than the ambient air temperature. Ticks burrow deep into this debris, often remaining within the top few inches of the soil surface.
Snow cover also aids winter survival by acting as a powerful insulator. A blanket of snow prevents the ground temperature from plummeting, keeping the soil and leaf litter underneath relatively stable and above lethal freezing points. Ticks must remain close to the ground because the insulating effect diminishes higher up. This sheltered environment, sometimes combined with animal burrows, provides the necessary protection for them to survive the season.
When Ticks Become Active in Winter
The greatest risk during winter is that ticks, particularly the black-legged or deer tick, can reactivate and begin host-seeking behavior during temporary thaws. While they may be dormant during a hard freeze, the cold does not kill them. The black-legged tick can become active and begin questing for a blood meal once the temperature rises above approximately 35 to 40 degrees Fahrenheit.
This means ticks can emerge from their sheltered spots during any unseasonably mild winter day, especially when the ground is unfrozen and there is little snow cover. The misconception that ticks are only a warm-weather problem increases the risk of an encounter. Checking for ticks remains a necessary precaution even after a mild winter hike, as the potential for disease transmission is present year-round.