Unexpected Encounter with American Dog Ticks (Dermacentor variabilis) at an Urban Park in Freezing Air Temperature

Mallory Harmel^1,*, Maddy Middleton¹, and Rachel M. Pigg¹

¹University of Louisville, Biology Department, Louisville, KY 40292. *Corresponding authors.

Northeastern Naturalist, Volume 32, Issue 3 (2025): N56–N62

First published early online: 28 September 2025

Abstract
We describe the collection of questing Dermacentor variabilis (American Dog Tick) outside its previously recorded seasonal active temperature range. In November 2023, we found 2 females host-seeking at an urban park in Louisville, KY, when the average air temperature was -1.0 °C. American Dog Ticks have a widespread distribution in North America and are typically active from March to September depending on location. Laboratory studies suggest they can survive temperatures as low as -15 °C, but before our collection, no active, host-seeking American Dog Tick had been reported below 0 °C in the field. As this species is a known vector for diseases of public health and economic concern, we encourage more research into its winter behavior and adaptations to cold tolerance.

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