Understanding tick activity is important for public health, as these arachnids can transmit various diseases. While often associated with warmer months, ticks are influenced by environmental conditions, making them a year-round concern. Knowing when and where ticks are active, or when their activity is reduced, helps to minimize exposure.
Understanding Tick Activity and Dormancy
Ticks do not truly hibernate but enter a state of reduced activity when temperatures drop. For many common human-biting ticks, such as the black-legged (deer) tick, activity significantly decreases below 40°F (4.4°C). This threshold is not absolute; ticks can become active during warmer spells, even in winter, when temperatures rise above freezing. Some species, like the American dog tick and Lone Star tick, become inactive at or below 40°F, while deer ticks remain active in above-freezing temperatures.
During cold periods, ticks employ survival strategies, as cold alone typically kills only about 20% of a tick population. They seek shelter in insulating layers such as leaf litter, soil, or under snow cover. Some ticks may even remain attached to warm-blooded hosts like deer or rodents, benefiting from their body heat. Finding refuge allows them to conserve energy and endure harsh conditions until warmer temperatures return, enabling them to resume questing for a blood meal.
Factors Influencing Tick Survival and Behavior
Beyond air temperature, other environmental factors play a significant role in tick survival and activity. Humidity is important for ticks, as they require high moisture levels, typically between 80% and 90%, to survive. Low humidity can lead to desiccation and reduced survival, causing ticks to seek refuge in moist microclimates like leaf litter or dense vegetation.
Snow cover often acts as an insulating layer, creating a stable microclimate beneath it. Without snow, the ground can become much colder, potentially increasing tick mortality. Leaf litter provides shelter, and is a preferred habitat for ticks to overwinter. The presence of suitable hosts, such as deer and rodents, impacts tick populations by providing blood meals for development and reproduction.
Seasonal Risk and Prevention
Tick activity varies throughout the year, with peak seasons typically occurring from early spring through late fall, generally from April to September. However, ticks can be active year-round whenever temperatures rise above freezing, challenging the notion that they are only a warm-weather concern. Milder winters and warmer temperatures can extend the period of tick activity, increasing the potential for human exposure.
To minimize tick bites, several prevention strategies are recommended:
Stay on paths and avoid tall grass, brushy areas, and leaf litter when outdoors, as these are common tick habitats.
Wear protective clothing, such as long-sleeved shirts, long pants tucked into socks, and light-colored fabrics to easily spot ticks.
Apply EPA-registered insect repellents containing ingredients like DEET or picaridin to exposed skin.
Treat clothing and gear with permethrin for additional protection.
After spending time outdoors, thoroughly check your body, clothing, and pets for ticks, and shower within two hours to help remove unattached ticks before they can bite.