DIPTERA. 191 



should be to be most effective), the first step in the 

 extermination of the house fiy would have been taken. 

 Then the second step would be the removal of all filth, 

 including sputa in spittoons and on sidewalks and floors, 

 and decaying garbage of all kinds; thus making the flies 

 much less dangerous as disease carriers. Much of the 

 danger which threatens us by way of the house fiy is the 

 result of our own carelessness and disregard of the laws 

 of health. The stable fiy, as has been said, often comes 

 into our dwellings ; and it may bite us after it has bitten 

 some other animal infected with some disease, or after 

 having crawled over some filth full of disease germs. 



One of the notorious crop pests of the order is the 

 hessian fiy. The first heard of it was in 1778; hence 

 it is an ancient enemy of American wheat fields, and if it 

 were not for its natural enemies, wheat growing would 

 soon become a thing of the past in the United States. 

 As it is, conditions are bad enough, and natural as well 

 as artificial means should be encouraged for the stamping 

 out of this pest. 



The fly is a little more than one-eighth of an inch 

 long, with a pinkish or brownish abdomen, the remaining 

 body regions being mainly black. The female lays her 

 eggs in the lengthwise furrows of wheat leaves on the upper 

 side. The hatching larvae travel downward and work 

 themselves inside of the sheath of the leaves and begin 

 the absorption of the wheat sap. After a few weeks of 

 this kind of feeding, the insects pass into the pupa stage 

 famiHarly known as the "flax-seed stage," because of the 

 close resemblance of the pupa to the seeds of this plant. 

 The adults, which soon come up out of the pupa cases, live 

 only a few days, and during this short time the egg-laying 

 is done for the second brood, which usually appear in 



