276 



ORDER DIPTERA 



adults appear much like the house flies or the stable fly but 

 have usually numerous prominent bristles and spines, the 

 bristles (arista) of the antennae lack the fine hairs which are 

 characteristic of most of the Muscidae. 



These insects show some very striking adaptations in their 

 parasitic life, some of the species depositing their eggs 

 directly upon the bodies of the caterpillars which are to be 

 the hosts of the larvse. The larv« on hatching bore at once 

 into the caterpillar and develo]) within its tissues. In cer- 



FiG. 221. — Euphorocera claripennis, a parasite of the alfalfa caterpillar: 

 adult and enlarged antenna of same; puparium — enlarged. (From Howard, 

 Bur. Ent.. U. S. Dept. Ag.) 



tain species the eggs are laid upon the leaves and depend 

 for their entrance to a host insect upon the leaf being eaten 

 by some herbivorous form and in this case it would se^m as 

 if there would be some chance of the eggs being crushed or 

 the lar\pe being destroyed in the process of swallowing. In 

 one rather remarkable form the eggs are evidently deposited 

 within the burrows of wasps which are stored with spiders. 

 The TachinidcB follow the wasps as they drag their victims 

 to the burrow and when the wasp enters they no doubt 



