Tabanus sudeticus, also known as the dark giant horsefly, is a species of biting horse fly. It is the heaviest fly in Europe.
Description The dark giant horsefly's length is around 20-25 millimeters. They have uniform dark brown eyes. Diagnostic characters include:-Upper facets of eyes distinctly larger than lower facets, and sharply delineated from them. Subcallus entirely dull and tomented, (it may have brown (areas); venter of abdomen with each segment black basally, and in a rounded median extension; black species, with yellow abdominal triangles, but little or no lateral reddish colour. Parafacials with abundant black hairs.Oldroyd, H., 1969 Diptera Brachycera: Tabanoidea and Asiloidea (Handbooks for the Identification of British Insects 9/4) Royal Entomological Society, London.
Dark giant horseflies are a common species to be found buzzing around cows and horses. They usually only suck blood from horses and cows, avoiding humans. They fly with a very loud buzzing.
Distribution
Tabanus sudeticus is found in many countries of Western Europe. It has a marked northern and western distribution; being found as far north as Southern Norway and the Western Isles of Scotland, and with an occasional record from Belarus.
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