AFFECTION OF INSECTS FOR THEIR YOUNG. 229 



State is not exposed to the attacks of one or other of them ; and even the 

 pupae, nay the very eggs of these animals, are not safe from their insidious 

 manoeuvres. The size of the different species varies in proportion to that 

 of the bodies which are to be their food ; some being so inconceivably 

 small that the egg of a butterfly not bigger than a pin's head is of suffi- 

 cient magnitude to nourish two of them to maturity^ ; others so large, that 

 the body of a full-grown caterpillar is not more than enough for one. 

 They are the larvae of these Ichneumons which make such havoc of our 

 pigmy tribes : the perfect insect is a four-winged fly, which takes no other 

 ibod than a little honey ; and the great object of the female is to discover 

 a proper nidus for her eggs. In search of this she is in constant motion. 

 Is the caterpillar of a butterfly or moth the appropriate food for her 

 young? You see her alight upon the plants where they are most usually 

 to be met with, run quickly over them, carefully examining every leaf, and, 

 having found the unfortunate object of her search, insert her sting into its 

 flesh and there deposit an egg. In vain her victim, as if conscious of its 

 fate, writhes its body, spits out an acid fluid, menaces with its tentacula, 

 or brings into action the other organs of defence with which it is provided. 

 The active Ichneumon braves every danger, and does not desist until her 

 courage and address have insured subsistence for one of her future progeny. 

 Perhaps, however, she discovers, by a sense the existence of which we 

 perceive, though we have no conception of its nature, that she has been 

 forestalled by some precursor of her own tribe, that has already buried an 

 egg in the caterpillar she is examining. In this case she leaves it, aware 

 that it would not suffice for the support of two, and proceeds in search of 

 some other yet unoccupied. The process is of course varied in the case 

 of those minute species of which several, sometimes as many as 150, can 

 subsist in a single caterpillar. The little Ichneumon then repeats her 

 operations, until she has darted into her victim the requisite number 

 of eggs. 



The larvae hatched from the eggs thus ingeniously deposited, find a 

 delicious banquet in the body of the caterpillar, which is sure eventually 

 to fall a victim to their ravages. So accurately, however, is the supply of 

 food proportioned to the demand, that this event does not take place until 

 the young Ichneumons have attained their full growth : when the cater- 

 pillar either dies, or, retaining just vitality enough to assume the pupa state, 

 then finishes its existence; the pupa disclosing not a moth or a butterfly, 

 but one or more full-grown Ichneumons. 



In this strange and apparently cruel operation one circumstance is truly 

 remarkable. The larvae of the Ichneumon, though every day, perhaps 

 for months, it gnaws the inside of the caterpillar, and though at last it has 

 devoured almost every part of it except the skin and intestines, carefully 

 all this time avoids injuring the vital organs, as if aware that its own exis- 

 tence depends on that of the insect on which it preys ! Thus the cater- 

 pillar continues to eat, to digest, and to move, apparently little injured, to 

 the last, and only perishes when the parasitic grub within it no longer 

 requires its aid. What would be the impression which a similar instance 

 amongst the race of quadrupeds would make upon us? If, for example, 

 an animal — such as some impostors have pretended to carry within 



' Bonnet, ii, 344. 



20 



