While many assume ticks disappear with the first frost, many species, especially blacklegged ticks (deer ticks), survive freezing temperatures by adapting to harsh conditions. Their activity significantly decreases during colder months, but understanding how and where they survive is important for knowing when they might become active again.
Tick Survival in Cold Weather
Ticks possess physiological adaptations that enable them to endure freezing temperatures. One primary mechanism is diapause, a state of metabolic dormancy similar to hibernation, where their development and activity are temporarily suspended. This allows them to conserve energy when environmental conditions are unfavorable.
Ticks also produce natural “antifreeze” compounds, known as cryoprotectants, within their bodies. Glycerol is a common cryoprotectant found in many cold-hardy arachnids. This substance prevents the formation of ice crystals within their cells, which would otherwise cause lethal damage.
By increasing the solute concentration in their cells, cryoprotectants lower the freezing point of their bodily fluids. This cellular adaptation, combined with their ability to reduce water content, helps ticks withstand prolonged periods of sub-zero temperatures. Some studies indicate certain tick species can survive temperatures as low as -12°C (10°F) for extended durations.
When Ticks Become Active
While ticks can survive cold, their activity levels are driven by temperature. Most tick species, including the blacklegged tick, become active when temperatures rise above 4°C to 7°C (40°F to 45°F). This means mild winter days above freezing can trigger them to emerge.
Blacklegged ticks are known to be active anytime the temperature is above freezing, even with snow on the ground. This questing behavior, seeking a blood meal, can occur during warm spells in January, February, and beyond. In contrast, other species like the American dog tick and Lone Star tick are inactive during colder fall and winter months.
The timing of their activity also depends on their life stage. Adult blacklegged ticks are typically encountered during mild winter days, as they seek hosts in late fall and reactivate with temperature increases. Larvae and nymphs are less likely to become active until temperatures and daylight hours increase significantly in spring.
Where Ticks Seek Shelter
To survive cold, ticks retreat to specific microhabitats that offer insulation and protection from extreme conditions and desiccation. A primary refuge is within leaf litter, where fallen leaves provide insulation from freezing air temperatures and maintain higher humidity.
Ticks also find shelter under snow cover, which acts as an insulating layer, creating a stable environment near the ground that is warmer than the ambient air. They burrow into the soil or find crevices in rotting wood and other decaying vegetation.
Dense vegetation and tall grasses also provide suitable hiding spots near the ground. By staying close to the soil surface and under protective layers, ticks minimize exposure to harsh winds and extreme temperature fluctuations, allowing them to persist through winter.