CH. a.] THE CALL-INSECT. 165 



suppose that the irritation should cause a greate 

 quantity of juices to flow towards the punctured 

 part. 



The gall-insects remain five or six months m the 

 larva state, before changing to nymphs ; some un- 

 dergo all their metamorphoses within the gall-nut, 

 and piercing their prison, come forth as perfect in- 

 sects: others quit it and bury themselves in the 

 earth, until they arrive at maturity ; soon after which 

 the female becomes impregnated and lays her eggs. 

 Carefully concealed in the manner just described, 

 they escape most of their natural enemies ; but fre- 

 quently some of the ichneumon tribe contrive to 

 introduce their eggs into the same habitation, and 

 the larva as it grows up feeds on the young of the 

 gall-fly. 



This shows that even insects, which nature seems 

 to have gifted with the most surprising foresight, 

 cannot provide against all the hazards to w^hich their 

 young are exposed. What could an anxious mother 

 do more, than to conceal her offspring in so solid 

 and secret a habitation, as that which envelopes the 

 young gall-fly? But insects, as small or smaller 

 than those into which the larvae are transformed, 

 know how to pierce the sides of the cells and to de- 

 posite within them an egg, which shall produce a car- 

 nivorous worm, for whom the rightful tenant of the 

 mansion serves as food. When some of these galls 

 are opened, two worms of different sizes will fre- 

 quently be found, the least sucking the biggest, while 



