INSECTS INFESTING THE APPLE TREE. 



73 



the 



which are acted upon by small muscles ; when these mus- 

 cles contract and relax, which they do with great rapidity, 

 the drum-heads are alternately tightened and loosened, pro- 

 ducing a rattling noise, Hke that caused by a succession of 

 quick pressures upon a convex piece of tin-plate. The body of 

 the female is provided with a piercer, with which she makes 

 numerous small slits in the under side of the branches (Fig. 

 36d,) of various shrubs and trees. The branches thus muti- 

 lated usually die back to the place where the slit nearest the 

 trunk occurs, and are frequently broken off by the wind. 



Fig. 36. — Seventeen-year Locusts, pupa and eggs ; a, 

 pupa— color. Fig. 36. 



y ello wi sh - 

 brown ; h, the 

 cast pupa skin; 

 cZ, a punctured 

 twig, contain- 

 ing eggs ; e, two 

 of the eggs re- 

 moved from 

 the twig — col- 

 or, yellowish ; 

 c, the adult, or 

 perfect insect — 

 colors, black- 

 ish, and dull 

 orange. 



As soon as hatched, the young grub enters the earth, but 

 this is as far as its history is known with any degree of cer- 

 tainty, except that when about to be changed into a perfect 

 insect it comes out of the earth and ascends a plant (Fig. 36&), 

 to which it attaches itself firmly by means of its hooked claws. 

 In a short time the skin on its back splits open and the 

 included insect issues in its perfect or winged form. 



Some kinds are known to live for thirteen and even seven- 

 teen years in the larva state. They do not pass through a 

 quiet pupa state as butterflies and many other insects are 

 6 



