Not all insects are inactive in winter in the temperate zone. In areas with snow cover, there are insect species adapted to life on top of the snow such as Snow Fleas (Collembola) and other species adapted to sub-nivean habitats or life underneath the snow.
Jaskuła & Soszyńska-Maj* list 79 species of ground beetles (Carabadae) that remain active under the snow pack. These beetles have adaptations to prevent their bodies from freezing at low temperatures. They are not frozen even though their surrounding are. Snow insulates the ground from the more extreme air temperatures above the snow pack. Actively composting plant material can provide warmth for activities such as feeding and mating. Warmer periods are associated with Subnivean carabids can sense low atmospheric pressure that is associated with warmer periods. These warm periods or “thaws” can influence activity.
Recent changes in climate may create conditions where snow may not always be present in the winter. For species adapted to living under the snow, changes in climate can reduce the available habitat or shift it closer to the poles.
*Radomir Jaskuła and Agnieszka Soszyńska-Maj. What do we know about winter active ground beetles (Coleoptera, Carabidae) in Central and Northern Europe? Zookeys. 2011; (100): 517–532.