TABANWm 



815 



Family Tabanid^. 



Orthorrhapha Brachycera with bulky bodies and often large 

 heads. The eyes usually meet in the males, but are separate in 

 the females. Antennas with third joint marked by four to eight 

 annuli, but without a terminal bristle. Proboscis strong and 

 prominent. Thorax narrower than the head. Wings with large 

 basal cells and five posterior cells. Third longitudinal vein bifur- 

 cate. Legs moderately stout. Empodia large. 



Fig. 407. — Tabanus hovinus Linn^us: _Female. 



Remarks. — The Tabanidse are blood-sucking flies, of which some 

 2,000 species are known. The blood-sucking habit is confined to 

 the females, while the males live on the juices of plants. They 

 are variously known as horse-flies, breeze-flies, gad-flies, serut-flies 

 (Nile), and mangrove-flies (West Africa), and are distributed widely 

 over the world. They are in the habit of coming to water for 

 drinking purposes, and this has enabled them to be killed in large 

 numbers by sprinkling the water with kerosene, which probably 

 prevents them escaping from the surface of the water, and partially 

 kills them by its poisonous effects. 



Morphology. — As a rule the head is as wide or wider than the thorax, convex 

 anteriorly, and concave posteriorly, with very large, brilliantly coloured eyes, 

 with golden-green or pUrple marldngs. 



The antennae are very distinct, but the proboscis varies, being very short 

 in some genera and enormously long in others. In the genera in which it is 

 short it hangs vertically downwards from the head. It consists of a labrum, 

 two maxillae with palps, two mandibles, a hypopharynx, and a thick labium 



