ENEMIES OF THE CATERPILLAR. 
73 
stand by, and watch the whole process, without 
disturbing her. 
The caterpillar does not to seem to mind it; 
though sometimes it will jerk itself about, and 
put out its horn as if to drive away its assailant. 
But the fly takes no notice? and goes on until 
she has laid all her eggs. 
In process of time the eggs become little grubs; 
and begin at once to feed upon the caterpillar, 
and to work their way still deeper into its body. 
They take care, however, not to touch the vital 
parts, as if they knew that were the caterpillar to 
die, their supply of food would be cut off. So 
the caterpillar is not hurt, and goes on eating 
and moving about, as if nothing were the matter. 
But when the little grubs are fully grown, and 
want to get out, they gnaw their way through 
the caterpillar’s skin; and then it dies, instead of 
changing into a chrysalis. 
There are a great many species of ichneumon 
flies. Some are so small, that they lay their eggs 
in the egg of the butterfly; and others are so 
large, that a full-sized caterpillar can only nourish 
one of their grubs. One ichneumon lays her 
eggs, not within the caterpillar’s body, but upon 
the outside of its skin; perching them on little 
footstalks, that are so firmly fixed, it is impossible 
to shake them off. When the eggs become grubs, 
F 
