Global warming and the change of butterfly distributions: a new opportunity for species diversity or a severe threat (Lepidoptera)? In order to assess the influence of climatic changes on the distribution of insects, the ranges of nonmigratory European butterfly species have been studied. This study revealed that the northern limits of 32 (64%) of 52 species have expanded northwards during the 20th century. The southern limits of ten (25%) of 40 species have retracted northwards. The example of the Peacock butterfly (Inachis io) is given to illustrate the response to climatic changes of a species of which the range is not restricted by habitat choice. The northern limit of its range shows a considerable shift to the north during warm periods, and a southward retraction during cooler periods. Several other species showed the same pattern. These results are followed by a discussion of the impact of climate change on species diversity.