The question of whether cold temperatures eliminate ticks is a common one. Many people assume that the arrival of winter means an end to tick activity and the associated risks. However, ticks are remarkably resilient creatures that have developed various strategies to survive in cold environments. Understanding how ticks endure winter conditions is important for recognizing the year-round potential for tick encounters.
Cold’s Impact on Tick Survival
While extreme and prolonged cold can reduce tick populations, it rarely eradicates them entirely. Laboratory studies show that most tick species may die at temperatures around 10°F (-12°C) or below with extended exposure. Some individuals, like blacklegged ticks (Ixodes scapularis), can survive much lower temperatures, even down to -7°F (-21.7°C). Short cold snaps or mild winters are generally insufficient to kill off a large number of ticks.
Only about 20% of a tick population typically succumbs to cold temperatures alone, even during frigid winters. The impact of cold on tick survival is often less significant than other factors. For example, a lack of insulating snow cover can increase tick mortality, as ticks are more exposed to freezing air temperatures. However, even without snow, ticks can survive in leaf litter.
How Ticks Endure Winter
Ticks employ several biological and behavioral mechanisms to survive cold temperatures. Many species enter a state of dormancy known as diapause, a period of suspended development or activity triggered by environmental cues like changing day length. This allows them to conserve energy and wait for more favorable conditions. While in this low-energy state, ticks can become active again if temperatures rise above freezing, even for a short period.
Seeking shelter is another strategy ticks use to endure winter. They commonly burrow into leaf litter, soil, or under snow cover, which provides insulation from extreme surface temperatures. Snow acts as an effective insulator, creating a protective layer that shields ticks from the coldest air. Some tick species also produce antifreeze-like compounds, such as antifreeze glycoproteins (AFGPs), which prevent ice crystals from forming in their cells and damaging tissues.
Personal and Household Tick Control Strategies
While general cold weather does not reliably eliminate ticks in the environment, targeted methods can be effective for personal and household tick control. Freezing items can kill ticks; for instance, clothing potentially carrying ticks can be placed in a freezer for several days. This method is useful for items that cannot be washed in hot water or dried on high heat.
For clothing, drying on high heat is a highly effective way to kill ticks, as it dehydrates them. Ticks often survive washing machine cycles, especially with cold or medium temperature water. However, they cannot withstand the high heat of a dryer. Therefore, placing clothes directly into a dryer on high heat for at least 10 minutes, or longer if damp, is recommended. Similarly, washing pet bedding regularly with detergent and drying it on high heat can help eliminate ticks.