CH. IX.] THE GALL-INSECT. 165 



suppose that the irritation should cause a greater 

 quantity of juices to flow towards the punctured 

 part. 



The gall-insects remain five or six months in 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 which 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 



