THE FLY 



85 



Fig. 90. — Cecidomyia, the Hessian- 

 fly, a, larva ; b, pupa. From 

 the " Standard Natural History." 



The eggs are laid in a boat-shaped mass, which floats on the 

 surface of the water. The larvae escape from the lower ends 

 of the egg-cases, and are known 

 as " wigglers." The larvae of 

 some species rest vertically near 

 the surface of the water, head 

 downward, with the tail end of the 

 body at the surface of the water, 

 since respiration takes place at 

 that end (Fig. 91, A, c) ; other 

 species he horizontal at the sur- 

 face of the water. Upon emerg- 

 ing from the water, the mosquito 

 floats in its pupal skin until its 

 legs and wings harden. Since a disturbance in the water at 



this time would jeopardize 

 the life of the mosquito, this 

 insect always breeds in quiet 

 waters (Fig. 92). From the 

 habits of the larvae it follows 

 that they can be easily lolled 

 while in the pond by pour- 

 ing kerosene oil on the 



Fig. 91. — Culex, the mosquito. ^, larva: . r ,i • r ri 



.. ■ t i u D J *i, water, tor this forms a nlm 



c, ]ts respiratory tube. B, pupa ; a, the ' 



respiratory tubes ; a, the end of the on the Surface and prevents 



abdomen with the two oar-like swim- . . . 



ming appendages, dorsal %dew. After respiration. MinnOWS \^all 



drawing of E. Burgess. free a pond from larva; if the 



edges of the pond are kept free from grass so as to allow the 

 fish to get to them. 



Mosquitoes are not merelj^ a nuisance, but are disseminators 

 of some of the most dangerous of human diseases. Malaria 



