Most species inhabit moist areas rich in organic matter. Most human reactions resulting from fly bites are initial pain, local irritation and swelling. Large local and systemic reactions do occur in hypersensitive people. Deer flies, yellow flies and horse flies are collectively called Tabanids. Over 3000 species occur worldwide.
Deer flies prefer wet breeding sites and horse flies prefer wet soil near water.
Tabanids depend on vision and odors to detect hosts. Carbon dioxide emissions from humans and animals are probably the single most attracting element to many Tabanids. Feeding varies with species. Some Tabinids attack the upper parts of walking man and others prefer the lower limbs, however, most are day biters. A Tabanid fly.