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Tabanidae (horse-flies, gadflies, stouts, clegs, deerfly, breezes, greenhead; order Diptera, suborder Brachycera) Large family of flies, which are often large, stout, and lack bristles. The third antennal segment is annulated, but without a style. The eyes are very large in relation to the size of the fly, and are extended laterally. The bright, colourful, often iridescent eyes are perhaps the most obvious feature of the adult. The mouth-parts have a projecting proboscis which in the female is adapted for piercing. Squamae are large. Adults are active on warm summer days and are rapid and often noisy fliers. They are particularly troublesome to cattle and horses, and may be responsible for the transmission of the disease surra of horses. Eggs are laid in compact masses near damp soil, mud, or other substrate suitable for larval growth. The larvae are carnivorous, feeding upon other insects. The family is distributed world-wide, and about 2000 species have been described.