Insecta. 35 



Every one has noticed the big fly that occasionally is found in houses, 

 as it attracts attention by its loud buzzing and its bluish abdomen. 

 It is the blowfly, that lays its eggs on meat. It is a disgusting sight 

 to behold flesh " alive with maggots, 1 ' but when one reflects he sees 



Breathing tubes 



Pupa. Larva. 



FIG. 29. DEVELOPMENT OF THE MOSQUITO. 



what a wise provision of nature it is that such decaying matter should 

 be so promptly and effectually disposed of. Let the hunter sit down 

 to eat his lunch of biscuit and meat in any part of the Rocky Moun- 

 tains, and the chances are that before he has finished the blowflies will 

 have discovered the presence of flesh, and come buzzing around him. 



The botfly lays its eggs on the hairs of horses 1 fore legs and shoul- 

 ders. The horse gets them into the mouth from scratching itself by 

 biting, and swallows them. The larva attaches itself by means of hooks 

 to the inner wall of the stomach. Later it passes on through the intes- 

 tine, and the pupa completes its development in the dung. 



" Skippers " are the larvae of black flies, about half the size of the 

 house fly, that lay their eggs on cheese, ham, and bacon. Bills received 

 from packing houses often specify that they do not guarantee their goods 

 against skippers. 



There are also flies that injure plants. Among these the Hessian fly 

 is well known. The larva is to be found between the sheath of a blade 

 of wheat and the stalk, where it does its damage. There is also a 

 " wheat midge " which causes considerable loss. Nearly every one must 

 have noticed on the ends of willow twigs a gray cone-shaped growth. 

 This is caused by the developing larva of the "pine cone" gall gnat. 



The Mosquito. The mosquito lays its eggs on stagnant water. The 

 larvae are known as " wrigglers," and their well-known habits justify the 



