Ticks are small arachnids whose activity is closely linked to temperature. Understanding this relationship is key to anticipating when and where they might be a concern.
Tick Activity and Temperature Ranges
Tick activity is influenced by temperature, with different species exhibiting varying thresholds. Many, including the black-legged tick (deer tick), become active when temperatures rise above freezing, often around 4°C (40°F). This temperature is a tipping point where they begin to quest for a blood meal.
As temperatures climb, activity increases, with many species showing peak activity near 30°C (86°F). While 4°C (40°F) is a guideline for black-legged ticks, other species have different preferences. For instance, some tick larvae show optimal activity between 17-22°C (63-72°F), though overall activity can occur between 10-60°C (50-140°F). American dog ticks and Lone Star ticks become inactive around or below 4°C (40°F), and are less active in fall and winter than black-legged ticks. Warmer temperatures lead to increased host-seeking behavior, though activity is not uniform across all species or seasons.
How Ticks Endure Cold Weather
When temperatures drop below their activity thresholds, ticks do not perish; instead, they employ survival strategies. They enter a state of dormancy, a low-energy stage where their metabolism slows considerably. This conserves energy, allowing them to survive for extended periods without feeding. They are not truly hibernating, as they remain responsive to environmental changes.
To protect from freezing, ticks seek shelter in insulated microhabitats. They burrow into leaf litter, soil, or under dense vegetation for thermal protection. Snow cover also acts as an insulating blanket, maintaining a stable microclimate and protecting them from severe cold. Some may find refuge in tree or rock crevices, or remain attached to warm-blooded hosts like deer or rodents. For ticks to die from cold, temperatures must drop below -12°C (10°F) and remain at that level for an extended period.
The Concept of Ticks “Going Away”
The idea that ticks “go away” during colder months is a misconception. While their activity levels decrease, ticks do not disappear entirely. They persist through cold periods using survival mechanisms such as seeking shelter in leaf litter or under snow.
Because of these survival strategies, a risk of tick exposure exists year-round, particularly during unseasonably warm spells in winter. When winter temperatures rise above freezing, even briefly, dormant ticks can become active again and resume questing. This, especially with warming winter trends, means tick-borne diseases are becoming less seasonal and more of a year-round concern. Therefore, maintaining vigilance and taking protective measures against ticks is advisable regardless of the season.