354 



THE INSECTS 



fourth 



The arista is feathered both dorsally and ventrally with straight hairs. The fourtl 

 longitudinal vein bends down in a rather sharp angle as compared with Stomoxys, 

 which gives the first posterior cell of the latter rather a fusiform appearance. The 

 eyes are close together in the male, far apart in the female. The female lays about 

 125 eggs in a heap preferably in fermenting horse manure. The larva comes out in 

 about thirty-six hours. Very characteristic are the stigmata decorating the blunt 

 posterior ends. (See illustration.) 



The larval stage lasts seven to ten days and then the barrel-shaped pupal stage 



Phlebotomus [Psychodidae] 



(Phoridae) 



FIG. 86. Wing venation of Diptera. A, First posterior cell; , discal cell; b, 

 mid cross- vein; a, auxiliary vein; C, marginal cell; D, submarginal cell. 



is entered upon. This lasts about three days when the adult fly emerges. This is 

 termed a "coarctate" pupa. The larva shrinks and is surrounded by its old skin 

 which is termed a puparium. This fly is incapable of biting, the piercing organs 

 being fused with the labium, but may transmit disease directly, carrying infectious 

 material from the source, as in faeces, to the food about to be ingested. Their r6le in 

 typhoid fever is one of immense importance. By reason of its hairy sticky legs, 

 habits of frequent defecation and constant regurgitation the housefly is an important 



