146 



THE STUDY OF INSECTS 



The beetles lay their eggs in the ground. The newly hatched larva 

 is active, running about in search of its food, which consists, in some 

 species, of the eggs of locusts, in others of the egg and honey of some 

 solitary bee. 



In the case of those species that live in the nests of bees the larva 

 climbs a plant, and remains near a flower till it has a chance to seize 

 hold of a bee visiting the flower. The larva clings to the bee until she 

 goes to her nest, then, letting go of the bee, it remains in the cell and is 

 shut up there with the egg of the bee and the store of food which the 

 bee provides for her young. The beetle larva then devours the egg; after 

 which it moults and undergoes a change of form, becoming a clumsy 

 creature, which feeds upon the honey. Several other changes in form 

 occur before the beetle reaches the adult stage. 



The wonderful instinct by which the larva? of these blister-beetles find 

 their way to the nests of solitary bees has not yet reached perfection ; for 

 many of the larvae attach themselves to flies, wasps, honey-bees, and other 

 flower-visiting insects, and merely gain useless transportation thereby. 



The life cycle of the striped blister-beetle, Epicauta vittata, illustrates 

 the hypermetamorphosis through which the blister-beetles pass. The 

 female deposits her eggs in a mass of a hundred or more in a hole in the 

 soil. They hatch into very active larvae each of which is known as a 

 triungulin. The triungulin has long legs and runs about in search of 

 eggs of grasshoppers. It feeds ravenously on the eggs and in about eight 

 days molts to the second stage, called the caraboid stage, because it then 

 resembles the larva of a carabid beetle. In another week it molts and 

 assumes the appearance of a scarabaeid larva and is therefore called the 

 scarabasidoid stage of the second larva. In a short time it molts again to 

 the ultimate stage of the second larva. In about ten days more it molts 

 again and becomes the pseudo-pupa or the coarctate larva. This form 

 usually hibernates and in the spring transforms to the third larval stage. 

 In a few days this larva transforms to the pupa in an earthen cell and in 

 five or six days the pupa transforms to the adult beetle (Fig. 246). 



f\. 



FlO, 246. — liypermctamorphosis of the striped blister-beetle; A, triungulin; B, caraboid stage; D, scara- 

 baeidoid stage; C, coarctate larva; E, pupa; F, adult beetle. 



