INSECTS. 



199 



a light brown, with two longitudinal white stripes on the back. The per- 

 fect insect lays her eggs in the crevices of the bark ; not onh of the apple, 

 but of the pear, quince, and other trees belonging to the rose family. The 

 grubs hatched from the egg bore into the solid wood, then they turn upwards 

 and ascend some eight or ten inches. In the tree they remain some two 

 or three years, and then they turn the burrow outwards, so thai it ends 

 just beneath the bark. The larva now becomes a pupa, and a month later 

 the perfect beetle gnaws its way through the bark, and emerges into the 

 outer world to become the parent of a new generation. 



The life-history of this species is about like that of all the rest, of course 

 making due allowance for the change of food plant. To describe these 

 forms and their slight variations in habits, and the trees and shrubs 

 affected by them, would be to furnish a lot of dry details, for which the 

 reader had better refer to some of the many works on injurious insects. 

 There are, however, one or two peculiarities which may prove of interest. 

 One species of long-horn which lives in our southwestern states is espe- 

 cially fond of the printed portions of posters, and it gnaws them out. 

 leaving the white paper untouched. The hickory-twig girdler lays its eggs 

 in the bark of the slender twigs of the hickory and persimmon and then 

 girdles the twig below the egg, cutting away a ring. of bark with her jaws, 

 so that the portion which contains the eggs withers and dies, thus giving 

 the larva dead wood to feed upon. A somewhat similar habit 

 is noticeable in a species which feeds upon the oak. The eggs 

 are laid in the slender green twigs, and the larva then eats 

 away the interior, so that nothing but the thin bark is left, 

 which soon withers and dies, and the twig is soon broken off 

 by the wind and falls to the ground. The process has been 

 described at length by the late Dr. Fitch, and his account is so 

 interesting that the reader will pardon some extracts. 



" The worm being about half grown is now ready to cut 

 the limb asunder. But this is a most nice and critical opera- 

 tion, requiring much skill and calculation ; for the limb must 

 not break and fall while he is in the act of gnawing it apart, 

 or he will be crushed by being at the point where it bends and 

 tears asunder, or will fall from the cavity there when it breaks 

 and separates. To avoid such casualties, therefore, he must, after severing 

 it, have time to, withdraw himself back into his hole in the limb and plug 

 up the opening behind him beforo the limb breaks and falls. ... He 

 accordingly severs the limb so far that it will remain in its pos 

 a strong gust of wind strikes it, whereupon it will break off and fall. 



'But the most astonishing part of this feat remains to be noticed. 



Fig. 1ST. — The 

 hickory -gird- 

 ler (Oik-;, i, ret 

 cingulatus) at 



work. 



