ORDER DIPTERA: SCHIZOPHORA: THE MUSCOIDEA 147 



blood. The female deposits her eggs on bees and wasps, 

 in which the larvse when hatched become parasitic. By 

 some authors this family is included with the Aschiza. 



Family SepsidcB (Fig. 51) (o-^>/r(y = putrefaction). Small, 

 usually black flies, with round head and constricted " waist." 

 The auxiliary vein is often indistinct, and the wing commonly 

 has a dark spot, or spots, near the tip. The Sepsidce are 

 quick in flight, and run with great activity ; they may be 

 found on decaying animal and vegetable matter, in which 

 they lay their eggs. The maggots of Piophila live in cheese 

 and bacon, and may be recognised by their power of leaping 



Fio. 51.— A Sepsid Fly. 



or skipping ; they have been found in the pharynx and 

 intestine of man, having probably been ingested in cheese. 



Family OSCINID^. Small, bare, lightish-coloured flies 

 with a very simple wing-venation, there being no auxiliary 

 vein, no discal cell, and no anal cell. A small species of 

 Oscinis which often hovers about the eyes is said by 

 Castellani to be the cause of severe conjunctivitis. 



Family Trypetid^. Small flies with very elegantly 

 dappled wings and wing-venation like an Anthomyid (Fig. 

 69). The larvae are found in vegetables and fruit, to which 

 they may cause much damage. 



Family CORDYLURIDiii (Scatophagidae). The flies of this 

 family are among the largest of the Acalyptrate Muscids ; 

 their wing-venation is like that of an Anthomyid, but the 

 abdomen is always composed of more than 4 visible segments. 



