108 FIRST BOOK OF ZOOLOGY. 



sharp, piercing sting, and with this organ the necessary hole 

 is made through which the egg is deposited. 



A caterpillar soon hatches from the egg thus deposited 

 by the ichneumon-fly, and feeds upon the fatty portions of 

 the body of the larva in which it has been so placed. But 

 this larva containing the ichneumon-caterpillar, meanwhile, 

 completes its growth and changes into a chrysalis, when the 

 inclosed ichneumon-larva devours the entire contents of the 

 chrysalis, and then changing into the pupa state soon emerges 

 as an ichneumon-fly, to go in quest of caterpillars, in which 

 to deposit its eggs. Thus it will often happen that a num- 

 ber of cocoons have been collected, from which ought to 

 appear a certain kind of moth, for example, but from many 

 of them a brown ichneumon-fly will emerge, a sight quite 

 as startling, to one not familiar with insects, as if a robin 

 should be seen to hatch from a hen's-egg. 



If the pupils will collect from the fences a large number 

 of the chrysalides of the common yellow cabbage-butterfly, 

 and keep them in a box, with a piece of glass for a cover, 

 they will observe that while butterflies come from many, 

 from others, which have already changed to a lighter color, 

 little black flies will appear, crawling out of holes in the side 

 of the chrysalis which have been made by some of the im- 

 prisoned ichneumons. (See Fig. 104.) 



100. Nearly every species of insect is infested by one or 

 more species of ichneumons, which deposit their eggs within 

 the pupse, or the larvse, or even in the eggs themselves. 



There are some species of ichneumons which deposit their 



