A study of the fauna and ecology of horseflies (Diptera, Tabanidae) of northern Chukotka

The Tabanid fauna of north-western Chukotka in the Soviet Union includes only eight species, belonging to Chrysops and Hybomitra. One of these, H. sexfasciata (Hine), was found to be much more abundant than the others. Local populations of these Tabanids were closely adapted to the rigors of the environment; they all developed at the same time and the flight period was very short (averaging 15-20 days). Notwithstanding the long daylight period with almost 24 h of sunshine, flight began at 8-9a.m. and ended at 8-9p.m. Adult activity was almost completely governed by a combination of meteorological factors, principally air temperature and wind. The Tabanid population in this area was adversely affected by severe environmental conditions, such as cold, brevity of spring and summer, permanently frozen soil and paucity of forest vegetation as well as factors resulting from human activity, such as fires and intensive grazing of deer.