296 



COMPARATIVE ZOOLOGY. 



Fio. 265.— Metamorphosis of an Hemipter, Water-boatman {Notonecta'). 



vse and pupae are active, and resemble the imago. They 

 are nearly all vegetarian. Each family produces charac- 

 teristic sounds (stridulation). The representative forms 



Fio. 266— Seventeen-year Cicada (Cicada aeptendecim) : a, pupa; b, the same, after 

 the imago, c, has escaped throagh a rent in the back ; d, holes in a twig, where 

 the eggs, e, are inserted. 



