250 



ORDER DIPTERA 



aquatic and air-breathing, with tlie trachea opening at the 

 end of the abdomen. The pupae are also aquatic but keep 

 near the surface and spiracles open near the head. The pupa 

 case splits on the dorsal side and the mosquito rests on the 



Fig. 194. — Anopheles punctipennis: female. (From Howard, 

 Div. Eiit., U. S. Dept. Ag.) 



surface of the water until its wings are dried enough for flight. 

 One species has been observed whose eggs may remain over 

 winter in mud, and hatching and development depends upon 

 the presence of water. Mosquitoes breed in minute quanti- 



