DIPTERA 



39 



2. DIPTERA 



This order includes all the true flies. They are the only 

 insects except the male scale insects and a few May flies 

 which have but two wings. About forty thousand species 

 are known. Their study is of great importance because 

 among them are some of our most deadly enemies, while 

 others are our best friends. 



Mosquitoes 



The mosquitoes have a typical life history, and as they 

 are in all parts of the world even as far north as Lapland 

 and Greenland, the pupils will find no difficulty in secur- 

 ing specimens. Their habits may be 

 studied from April to November by 

 securing the eggs or larvae and plac- 

 ing them in a jar of water with some 

 algae (frog spittle, etc.) . These may 

 be found in quiet pools of water not 

 inhabited by fish. A rain barrel or a 

 pail of water that has remained out of 

 doors a few nights is apt to contain 

 them. 



Life History. The eggs of the com- 

 mon species, Culex, are laid so that the 

 two or three hundred stand on end 

 and stick close together, forming a 

 grayish floating mass nearly a quarter 

 of an inch long. They are deposited early in the morn- 

 ing and often hatch within a day into minute wrig- 

 gling larvce which continue to grow from seven to 



FIG. 14. Eggs of mos- 

 quitoes. A, Culex; B, 

 Anopheles photograph- 

 ed on the water, natu- 

 ral size. 



