290 



Beetles 



green, blue, and steel-black being common colors (PL II, Fig. 12). Some, 



however, are grayish, dead black, or yellowish and brown. All are leaf -feeders- 

 In the development of the blister-beetles an extreme condition known 



as hypermetamorphosis occurs, which is undoubtedly the result of a purpose- 

 ful adaptation brought about by long selection, but 

 which seems an almost impossible achievement of 

 such "blind" natural forces. The eggs are deposited 

 in the ground ; from them hatch minute active strong- 

 jawed larvae (Fig. 402) with three pairs of long legs, 

 each terminating in three claw-like spines. These 

 larvae are called triungulins. They run about 

 seeking food, which, varying with different species, 

 consists of the eggs of locusts, or the eggs and 

 honey of solitary bees. The triungulin of Epicauta 



FIG. 401. The striped vittata, one of our common Meloid species, studied 



by Ril e y explores cracks and burrows in the ground 



' ;, j r i 11 r / i 



until an egg-pod of a locust (usually of one of the 



destructive Melanoplus species) is found. Into this 

 the triungulin burrows and begins to devour the eggs. After a few days 

 given to eating a couple of eggs it moults and appears in a very different 



potato-beetle, Epicauta 

 vittata. (After Pettit; 

 twice natural size.) 



FIG. 402. Hypermetamorphosis of- Epicauta vittata. A, young larva or triungulin; 

 B, caraboid larva; C, coarctate larva; D, scarabaeoid larva; E, pupa; F, adult. 

 (After Riley; natural size indicated by line.) 



larval guise with soft skin, short legs, small eyes, and different body form 

 and proportions. One week later a second moult occurs, but without re- 



