An extralimital population in a warm climatic outpost: the case of the mothIdaea dilutaria in Scandinavia

The mothIdaea dilutaria Hübn. (Geometridae) has an isolated population on the Kullaberg peninsula in southern Sweden. Investigations of the local and micro-climate on the peninsula showed that the local distribution range of the moth coincided with the areas of warmest climate, supporting the hypothesis that the Kullaberg poppulation is dependent for its survival on the warm climate of this area and that the species here is a thermal relict from a previously warmer climatic period.