290 



Beetles 



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

 however, are grayish, dead black, or yellowish and biow n. 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 larvse (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 

 potato-beetle, Epicauta ty Ril ey explores cracks and burrows in the ground 

 vittata. (After Pettit; * , , , , , & 



twice natural size.) 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 



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- 



