A NATURALIST IN BRAZIL 



flew off with her. The distribution of the species is enlarged by such 

 nuptial flights, for it would be a long while before the earth-bound 

 female could conquer new territory. 



The Ichneumon-wasps are pretty little insects, very active, and 

 always whisking their antennae up and down. They may often be 

 seen on leaves or flowers on which Plant-lice (Aphides) have scattered 

 their saccharine excretions, so that the whole leaf or petal is sticky 

 and shiny. There the female Ichneumons seek their food, and the 

 males, as long as they live, never do more than lead a harmless 

 existence among the flowers. Not so the females. Their forethought 

 for their brood makes executioners of them. 



A caterpillar is peacefully nibbling at a leaf Suddenly it starts; 

 a tiny black wasp has flashed past its head. It returns, and desperately 



K4. 

 Fig. 23. — Ichneumon on Caterpillar 



the caterpillar lashes out at the enemy against whom its instinct 

 warns it. Many caterpillars even eject long jets of fluid from their 

 mouths, which are intended to intimidate the aggressor. But nothing 

 is of any avail ; suddenly the little wasp has seized her opportunity ; 

 she alights on the caterpillar, and plunges her ovipositor into its 

 flesh (Fig. 23). In most cases this happens before the caterpillar can 

 defend itself, for the Ichneumons fly silently ; they do not hum. 



By means of her tubular ovipositor the Ichneumon has thrust one 

 or more eggs into the caterpillar's body. The caterpillar quiets 

 down again, and pursues the only occupation of which it has any 

 knowledge, that of eating. But after awhile a larva emerges from 

 the egg in its body; in appearance a tiny maggot. And now it 

 begins to eat. But it does not simply devour whatever is beneath 

 its mandibles, for then it might sever some important nerve, and 

 the caterpillar would die. The whole object of laying the egg in 

 the living caterpillar is to ensure that the larva shall have fresh 

 meat until the time of its pupation. The insects cannot, like the 

 foxes or wolves, continually obtain fresh prey for their young; as a 

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