HYMENOPTERA 



251 



leaves the swollen skin of the aphis through a round hole. Often 

 whole colonies of aphides will be found to have been thus parasi- 

 tized. One little species (Lysiphlebus tritici) has been principally 

 responsible for subjugating the green-bug, or southern grain aphis, 



FIG. 396. Lysiphlebus tritici, male, the wasplike parasite 

 of the green-bug. (Very much enlarged) 



(After S. J. Hunter) 



which has been so destructive to grain in the southwest ; this par- 

 asite also attacks many other commonly injurious aphides. Larvae of 

 the large green tobacco or tomato worm (Phlegethontius quinque- 

 maculata (Fig. 333) 

 are frequently found 

 covered with what 

 appear to be small 

 silken eggs. These 

 are the cocoons of 

 little braconids of 

 the genus Apanteles 



which have devel- 

 oped within the cat- 

 erpillar's body. Not 



FIG. 397. Lysiphlebus parasite in act of depositing 

 eggs in the body of a grain aphis. (Much enlarged) 



(After Webster, United States Department of Agriculture) 



