134 The Rocky Mountain Locust. 



worm, will serve to illustrate the species, and, indeed, 

 differs from it very little except in being somewhat larger, 

 and in having the tip of the abdomen yellow. 



These Tachina-flies firmly fasten their eggs — which are 

 [Fig. 32.] oval, white and opaque, and 



quite tough — to those parts of 

 the body not easily reached by 

 the jaws and legs of their vic- 

 tim, and thus prevent the egg 

 from being detached. The 

 slow-flying locusts are attack- 

 ed while flying, and it is quite 

 amusing to watch the frantic 



Yellow-tailed Tachina-fly. efforts which One of them, 



haunted by a Tachina-fly, will make to evade its enemy. 

 The fly buzzes around, waiting her opportunity, and 

 when the locust jumps or flies, darts at it and attempts 

 to attach her egg under the wing or on the neck. The 

 attempt frequently fails, but she perseveres until she usu- 

 ally accomplishes her object. With those locusts which 

 fly readily, she has even greater difficulty ; but though the 

 locust tacks suddenly in all directions in its efforts to avoid 

 her, she circles close around it and generally succeeds in 

 accomplishing her purpose, either while the locust is yet 

 on the wing, or, more often, just as it alights from a flight 

 or a hop. The young maggots hatching from these eggs 

 eat into the body of the locust, and after rioting on the 

 fatty parts of the body — leaving the more vital parts 

 untouched — they issue and burrow in the ground, where 

 they contract to brown, egg-like pupse, from which the fly 

 issues either in the same season or not till the following 

 spring. A locust infested with this parasite is more lan- 

 guid than it otherwise would be ; yet it seldom dies till 

 the maggots have left. Often in pulling off the wings of 



