INSECTS 



adult behavior, are, however, most obnoxious creatures 

 during their larval stages. The ordinary blowflies, which 

 are related to the house fly, lay their eggs in the bodies of 

 dead animals, where the larvae speedily hatch and feed 

 on the putrefying flesh. Another kind of blowfly deposits 

 living larvae instead of eggs. These flies may be regarded 

 as beneficial in that their larvae are scavengers. But some 

 of their relations appear to have taken a diabolical hint 

 from their habits, for they make a practice of depositing 

 their eggs in open wounds, sores, or in the nostrils of living 

 animals, including man. The larvae burrow into the tis- 

 sues of the victims and cause extreme annoyance, suffer- 

 ing, and even death. A notable species of this class of 

 pests is the screw worm. Infestation by fly larvae, or 

 maggots, is called myiasis. 



Well-known cases of animal myiasis are that of the bot- 

 fly in horses and of the ox warble in cattle. The flies of 

 both these species lay their eggs on the outside of the 

 animals. The young larvae of the botfly are licked off 

 and swallowed, and then live until full-grown in the 

 stomach of the host. The young ox-warble larva burrows 

 into the flesh of its host and lives in the body tissues until 

 mature, when it bores through the skin on the back of the 

 afflicted beast, drops out, and completes its transforma- 

 tion in the ground. 



Not only animals but plants as well are subject to in- 

 ternal parasitism by fly larvae. Garden crops are at- 

 tacked by leaf maggots and root maggots; orchardists in 

 the northern States have to contend against the apple 

 maggot, which is a relation of the olive fly of southern 

 Europe and of the destructive fruit flies of tropical coun- 

 tries. That notorious scourge of wheat fields, the Hessian 

 fly, is a second or third cousin of the mosquito, and it is in 

 its larva form that it makes all the trouble. 



The special attention that has been given to pestiferous 

 flies must make it appear that the Diptera are a most 

 undesirable order of insects. As a matter of fact, however, 



[35*1 



