108 THE PERIODICAL CICADA, 
of the surrounding wood, there remains in the center of the twig a 
dead spot, and the white glistening egg shells of the escaping larve 
have been found in place six years after they have been inserted in 
the twig by the fomale Cicada. 
Considerable danger follows the work of the Cicada, in that as long 
as the wounds remain open or as dead spots on the limbs they arenot 
only a source of weakness in the case of winds, but they offer attract- 
ive situations for the attacks of various wood-boring insects. — If left 
to themselves the limbs might entirely recover, except for the scars, 
but the borers gaining entrance through these spots complete the work 
FIG. 43.—Periodical Cicada scars in hard-maple twigs after seventeen years. (Hopkins.) 
of destruction which the Cicada began. Furthermore, such open 
wounds or pockets in the twigs of fruit trees Doctor Hopkis has 
shown to be favorite points of attack for the woolly aphis (Schizon- 
~ eura lanigera Hausm.), the presence of which not only prevents the 
wounds from healing but causes additional abnormal erowth, adding 
considerably to the injury to the branches, and nike hea more 
liable to the attacks of other insects. 
