If you assume the chilly temps make ticks settle in for a long winter’s nap until spring, experts have some surprising news for you. “It’s important to not forget about ticks because even though it’s December or we’re getting right in the midst of winter, ticks can still be active; they’re not killed off by cold temperatures,” Patrick (PJ) Liesch, MS, extension entomologist and director of the Insect Diagnostic Lab at the University of Wisconsin-Madison, told Verywell. Here’s a fun fact about ticks: They’re ectothermic, which means their bodies can’t generate heat internally.