Does the tortoiseshell butterfly, Aglais urticaE (lepidoptera, nymphalidae) shiift to synanthropy in Northeast Asia?

An assumed shift of the tortoiseshell butterfly, Aglais urticae to synanthropy in extremely cold regions (with temperatures close to –60оC) is tested. The tortoiseshell butterfly overwinters at the stage of imago; their cold resistance being fundamentally insufficient for surviving the cold across most of their distribution range in natural shelters located above the snow level and in unheated buildings. The species' resistance to cold from England to northeast Russia is increased from –22 to –29оC, while the average minimum air temperature in January drops from 3.3 to –55.7оC. The objective of the present work was to find out whether well-built, but unheated houses (the village of Seimchan) provide winter indoor temperatures above –30оC, a threshold for the tortoiseshell butterfly. Winter temperatures were measured with loggers in two different houses and compared with the outside temperature obtained from weather station data. During a severe cold weather, it was 11–19оC warmer inside the houses than outside, but the minimum temperatures below –30оC were recorded over half of the winter, and below –35оC over almost its third. Thus, winter (unhea- ted) houses, as well as demi-seasonal ones, and natural shelters such as cracks under the bark, hollows and other cavities located above the snow cover fail to provide the required temperatures. Unheated well-built houses guarantee successful hibernation for the tortoiseshell butterfly only in the milder climatic conditions of western Siberia and in the northeast of the European part of Russia. Wintering above the snow level in primitive shelters can only be possible within the temperature range of –31...–20оC and west of it. The results of the work prove the idea of tortoiseshell butterfly synanthropy to be unsubstantiated and return to the idea of its wintering under the snow cover in shelters such as cavities in litter, under fallen trees, etc. This type of wintering guarantees success, being independent from the climate of northern Eurasia.