Distribution, Phenology and Adaptation to Arctic Environment in Trichoceridae (Diptera)

The world distribution of the genera of Trichoceridae is shown, and the geographic and annual distribution of species of the northern hemisphere, particularly Fennoscandia and the Subarctic and Arctic of North America, is discussed. The microclimates in which different developmental stages of trichocerid species live in subboreal, boreal and arctic environments are analysed qualitatively, and comparisons are made. It is found that species of the genera Metatrichocera and Trichocera also live in localities outside the arctic region in conditions comparable to the arctic environment. Different trends of adaptation for survival and activity in the arctic environment are discussed and compared with trends found in other cold-adapted insects. It is suggested that for most trichocerid species dispersal to arctic localities is a question of adjustment or acclimatization rather than of entirely new adaptations.