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 
The striped vittata, one of our common Meloid species, studied 
by Riley, explores cracks and burrows in the ground 
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. 401. 
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- 
