Wintering and Cold Hardiness of the Small Tortoiseshell Aglais urticae (Linnaeus, 1758) (Nymphalidae, Lepidoptera) in the West and East of the Northern Palearctic

The geographic variability of the cold hardiness poikilothermic animals is one keys to understanding mechanisms formation their ranges under climate change or anthropogenic introductions. A convenient object small tortoiseshell butterfly Aglais urticae, which distributed from Atlantic Ocean Pacific Ocean. On edges distribution range, difference between averages absolute minimum air temperatures reaches 60 °C. (supercooling point and lower lethal temperatures) imago wintering in a supercooled state northeast Russia was assessed comparison previously studied European ones. Despite huge temperatures, mean supercooling points east (−23...−29 °C) west (−17...−22 differ by only 7 °C; for this species near −30 identified not enough overwintering A. urticae on vast majority part range natural shelters above level snow cover. inhabiting regions with below °C possible when snow. This primitive behavioral adaptation probably does require physiological changes may be unique Lepidoptera.