Given the recent stretch of abnormally frigid weather, a common question posed to DCNR has been, “How will this affect ticks?”
Pennsylvania led the nation in 2016 with more than 12,000 confirmed cases of Lyme disease, which is transmitted to humans from the bite of the black-legged (or “deer”) tick.
The short answer is, “somewhat.”
Cold weather can impact tick populations.
Colder winters can cut down the number of ticks that survive through winter.
However, studies show only around 20 percent of the population die off.
Carefully controlled lab experiments, using freezers, show that ticks will die between -2 to 14 degrees Fahrenheit, but, there’s a catch.
Lab conditions can never emulate the full range of conditions that can and will affect a population of ticks. In a freezer, there is no escape. In nature, conditions can be quite different.
Landscape and physiology help them survive.
Evidence shows that natural landscape conditions and physiological adaptations bring ticks a reprieve from winter mortality.
Deep soils, leaf litter, and perhaps a blanket of snow all offer insulation from wildly fluctuating air temperatures. As temperatures fall, ticks naturally burrow deeper to escape the cold.
Ticks boast physiological adaptations that allow them to overcome cold snaps. They are reputed to be able to take advantage of cellular processes that decrease the proportion of water in their cells, thus decreasing cellular freezing point.
Scientists also hypothesize that ticks can manufacture a “cryoprotectant,” essentially natural antifreeze, which circulates in their cells. This is a well-known adaptation in some amphibians that inhabit colder climates.
Is it the bitter cold that impacts tick populations?
Some scientific studies on winter tick mortality have shown that it is not necessarily the cold that kills them, but rather, the magnitude and frequency of temperature changes.
Winters highlighted by a relative abundance of changes from warm to very cold seem to possess the greatest potential to substantially decrease tick populations. The applied rationale is that warmer temperatures lure ticks to the forest surface or onto vegetation, and the quick onset of cold then kills them before they can reach safe-haven in soil or leaf litter.
Although the colder temperatures could possibly reduce tick populations, the theme remains the same when considering risk.
Take precautions to prevent tick bites, no matter the time of year.
Remember, ticks can be carried by pets and wild animals, and can hitch a ride into your home on natural items like Christmas trees and firewood. It is important to always be vigilant when in contact with such items.
During non-winter seasons, DCNR strongly urges Pennsylvanians to take action to prevent tick bites.
When afield, always:
- Wear light-colored clothing (ticks stand out better)
- Spray tick repellents on your clothes
- Tuck your pantlegs into your socks
- Do a “tick check” upon returning home (on yourself, children, and pets).
Showering is also recommended after a day afield, as well laundering, then drying clothes in an electric dryer on a high heat setting.
For more information on ticks and tickborne diseases, visit the Centers for Disease Control and Prevention’s website.