194 AFFECTION OF INSECTS FOR THEIR YOUNG, 
pup, nay the very eggs of these animals, are not safe from their insidious 
manceuvres. 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 sufficient 
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 larvze of these Ichneumons which make such havoc of our pigmy 
tribes: the perfect insect is a four-winged fly, which takes no other food 
than a little honey; and the great object of the female is to discover a 
roper nidus for her eggs. In search of this she is in constant motion, 
ts the caterpillar of a butterfly or moth the appropriate food for her 
young ? you sce 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 ten- 
tacula, 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, some. 
times as many as 150, can subsist in a single caterpillar. The little Ich- 
neumon then repeats her operations, until she has darted into her victim 
the requisite number of eggs. 
The larvze 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 
caterpillar either dies, or retaining just vitality enongh 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 larva 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 exist- 
ence 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 re- 
quires 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 haye pretended to carry within them — 
should be found to feed upon the inside of a dog, devouring only those 
parts not essential to life, while it cautiously left uninjured the heart, 
1 Bonnet, ii. 844. 
