Adult flies of Tabanidae are colourful with a pair of large black, brown to green or yellow eyes with iridescent bands (when alive), which disappear after death. Females are dichoptic whereas males are holoptic. In females, frons usually has callus (plural: calli) with distinctive pattern for each species. Antennae are often porrect and horn-like, flagellum often elongated. stoutly built flies with large calypters; pretarsus with two pulvilli and an arolium, which are pad like; 3rd antennal segment (flagellum) elongated, clearly made up of several fused parts, with a prominent tooth at base in some groups. Wing with veins R4 and R5 divergent enclosing the tip of the wing. Wings are transparent/clouded as in Tabanus Linnaeus, mottled as in Haematopota Meigen, banded or striped as in Chrysops Meigen.
They are efficeint mechanical carriers of more than 25 animal diseases including trypanosomiasis (Veer, 2004) which is disease caused by protozoans of genus,Trypanosoma. Viral diseases transmitted by horse flies are rinderpest, Equine infectious anemia virus, Bovine Leukaemia virus and anaplasmosis. Anthrax and tularaemia are bacterial diseases transmitted by tabanids which can spread to humans. They are vectors for spirochaetes causing Lyme disease in United States and filaroid nematodes responsible for Loa loa in Africa Major pestiferous genera occuring in India are Atylotus Osten-Sacken, Chrysops Meigen, Haematopota Meigen and Tabanus Linnaeus in Chrysopinae and Tabaninae.