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

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.