473 



Family Hippoboscidge — The Bird Parasite Flies 



Olfersia sordida. 



Small, flat flies of leathery consistency, usually with wings, the 

 posterior veins weaker. 



Head flattened, usually attached to an emargination of the thorax. 

 Face short; palpi forming a sheath for the proboscis, projecting in 

 front of the head; antennas inserted in pits or depressions near the 

 border of the mouth, apparently with a single segment, with or without 

 a terminal bristle or hairs. Eyes round or oval; ocelli present or 

 absent. Thorax flattened; scutellum short and broad. Halteres present 

 or rudimentary, rarely absent. Abdomen sac-like, the sutures indistinct, 

 the basal segments usually fully chitinized. Legs short and strong, 

 broadly separated by the sternum; tarsi short; claws strong and often 

 wdth one or two teeth. Wings present or absent, the veins approximated 

 to the anterior border, with weak ones running obliquely across the pos- 

 terior two-thirds of the wing. Larviparous. 



