“The ichneumon on the hunt is one of the most curious sights imaginable. Caterpillars are peacefully browsing on leaves. An ichneumon comes along, flies about over them, selects the ones that look best for its purpose, and never fails to exclude those that already have eggs in their bodies. At the sound of their enemy’s wings the terrified caterpillars stop eating and begin to move their heads in a startled manner from side to side, doubtless in the hope of frightening off the foe. But the latter pays no attention to these vain threats; it alights on the caterpillar of its choice and, so quickly that you hardly have time to see the operation, darts its terebra and lays an egg in the wound.” “And doesn’t the caterpillar make any resistance?” asked Emile. “It performs some lively antics, but that is all. The poor creature cannot defend itself against an enemy in the air, a winged enemy that can always keep at a safe distance and is always ready to fly away. The other eligible caterpillars in the group are attacked in the same manner, one by one, until the ichneumon has laid all its eggs.” “Each caterpillar gets only one egg?” asked Jules. “That depends on the size of the egg-layer. If it is large it lays but one egg in each caterpillar, so that the larvæ may each have enough food; if small, it lays several.” “And then what happens?” Emile inquired. “The ichneumon gone, the pricked caterpillars soon recover their composure and resume their eating. The prick, not being poisoned with venom, causes very little pain; besides, it would take a good deal more than that to affect their appetites. All goes well for a few days, as long as the eggs are unhatched.” “Do those eggs hatch in the caterpillar’s body?” “Yes.” “And as soon as they have hatched do the little larvæ set to work devouring the caterpillar’s inside?” “That’s the way of it.” “What an awful stomach-ache for the poor caterpillars!” “Nevertheless, even with such pain as may result from the gradual consumption of their flesh, the caterpillars continue to eat as if nothing had happened, the satisfaction of their appetite making them forget their sufferings, so imperious is their need of food. And furthermore, for a reason that I will explain, the parasitic worms observe a certain caution in their ravages.