206 



LEPIDOPTERA. 



more seasons of drought, which are favorable for their 

 increase. They then begin to multiply, large numbers 



hibernate, and the 

 following spring mul- 

 titudes of moths ap- 

 pear, lay their thou- 

 sands of eggs, from 

 which the caterpil- 

 lars are hatched. As 

 soon as the surround- 

 ^^' ^^ ■ ing V e g e t a t i o n is 



eaten by these caterpillars, they are obliged to starve 

 or go elsewhere, and this explains their sudden appear- 

 ance in vast numbers in new regions. They devour 

 grass and grain. In 1770 they spread over New 



Fig. 159- 



England. "They went up the sides of the houses 

 and over them in such compact columns that nothing 

 of the boards and shingles could be seen. Pumpkin 

 vines, peas, potatoes, and flax escaped their ravages.- 

 But wheat and corn disappeared before them as by 

 magic. Fields of corn in the Haverhill and New- 

 bury meadows, so thick that a man could hardly be 

 seen a rod distant, were in ten days entirely defo- 



