100 



FIRST BOOK OF ZOOLOGY. 



appearance represented in Fig. 96. At the proper time they 

 crawl out of the ground, and their skins splitting open along 

 the back, out come the perfect insects, with wings and all 

 complete, to fly away, lay their eggs, and devastate the 

 forests. 



There are certain species which do not occur in such 

 numbers, and which pass through all their changes in a sin- 

 gle year. The cast-off skins of the pupre of such species may 

 be often found clinging to apple-trees and fences in New 

 England. 



FIG 96. PUPA-CASE OP A SPECIES OF NEW ENGLAND CICADA OR HARVEST-FLY, CLINGING 



TO A TWIG. 



The pupils should, if possible, collect a twig in which 

 the eggs have been deposited, a pupa-skin, and the perfect 

 insect. 



