THE FLY AND ITS ALLIES 



69 



FIG. 70. Cecidomyia, theHessian- 

 tfy. (/, larva; b, pupa. From 

 the " Standard Natural History." 



because it infests wheat seedlings and so weakens them that 

 they produce no grain. Other minute gnats or midges 

 are destructive to clover in 

 the United States, either by 

 binding the leaves together 

 and sucking the sap of the 

 destroying the 



plant or by 



young seed. 



The mosquitoes, or Culicidse, 1 



are so well known that it is 



hardly necessary to describe 



them. They can always be 



identified by the feathery an- 



tennse, by the presence of a 



fringe of hairs on the hind margin of the wing, and by the 



fact that the marginal vein runs all around the periphery of 



the wing. The larvse are 

 usually aquatic, but some 

 species which are abun- 

 dant on our Western arid 

 plains must breed in the 

 earth. The eggs of the 

 aquatic species are laid in 

 a boat-shaped mass, which 

 floats on the surface of the 

 water. The larvae escape 



abdomen with the two oar-like swim- from the lower ends of the 

 ming appendages, dorsal view. After 

 drawing of E. Burgess. 



FIG. 71. Culex, the mosquito. A, larva; 

 c, its respiratory tube. B, pupa ; cl, the 

 respiratory tubes; a, the end of the 



egg-cases, and are known 

 as "wigglers.'" The larvse 

 rest vertically near the surface of the water, head downward, 

 with the tail end of the body at the surface of the water, 

 1 Culex was Pliny's name for the fly. 



