INDIRECT BENEFITS DERIVED FROM INSECTS. 158 
Jarve!; and the ant-lion (Myrmeleon) and Reaumur’s improperly named 
worm-lion (Leptis), whose singular stratagems will be detailed in a sub- 
sequent letter, both of which destroy numerous insects that are so 
unfortunate as to fall into their toils. 
The Parasitic larve, an extremely numerous tribe, must next bé 
considered. These chiefly belong to the order Hymenoptera, and were! 
included by Linné under his vast genus Ichneumon, so named from the) 
analogy between their services and those of the Egyptian Ichneumons) 
(Viverra Ichneumon), the former as destroyers of insects, being equally’ 
important with the latter as devourers of serpents, the eggs of crocodiles, } 
&e. 
The habits of the whole of this tribe?, which properly includes several =~ 
families (Ichnewmonide, Chalcilide, &c.) and a great number of distinct 
genera, are similar. They all oviposit in living insects, chiefly while in the 
larva state, sometimes while pupa (Misocampus Puparum); at others 
while in the egg state (Pferomalus ovulorum, and bifasciatus, Chrysolampus 
iristis, &c.). The eggs thus deposited soon hatch into grubs, which imme- 
diately attack their’ victim, and in the end insure its destruction. The 
number of eggs committed to each individual varies according to its size, 
and that of the grubs which are to spring from them; being in most cases 
one only, but in others amounting to some hundreds. 
From the observations hitherto made by entomologists, the great body 
of the Ichneumon tribe is principally employed in keeping within their 
proper limits the infinite host of /epidopterous larvee, destroying, however, 
many insects of other orders ; and, perhaps, if the larva of these last fell 
equally under our observation with those of the former, we might discover 
that few exist uninfested by their appropriate parasite. Such is the 
activity and address of the Ichneumonidans, and their minute allies 
(Pupivora Latr.), that scarcely any concealment, except, perhaps, the 
waters, can secure their prey from them ; and neither bulk, courage, nor 
ferocity avail to terrify them from effecting their purpose. They attack 
the ruthless spider in his toils; they discover the retreat of the little 
bee, that for safety bores deep into timber; and though its enemy 
Ichneumon cannot enter its cell, by means of her long ovipositor she 
reaches the helpless grub, which its parent vainly thought secured from 
every foe, and deposits in it an egg, which produces a larva that destroys 
it. In vain does the destructive Cecidomyia of the wheat conceal its 
larvee within the glumes that so closely cover the grain; three species of 
these minute benefactors of our race, sent in mercy by Heaven, know how 
to introduce their eggs into them, thus preventing the mischief they would 
otherwise occasion, and saving mankind from the horrors of famine. — In 
vain, also, the Cynips by its magic touch produces the curious excrescences — 
on various trees and plants, called galls, for the nutriment and defence of 
its progeny ; the parasite species attached to it discovers its secret chamber, 
1 Macquart, Dipteres, i. 482. ° 
2 Latreille denominates this family, as he calls it, Pupivora ; if by this he alludes 
to their dew ouring the young of insects, from the classical meaning of the word pupa, 
the term is very proper; but this should be borne in mind, as the majority of readers 
would imagine it to refer to the pupa state of insects, in which they are not so gene- 
rally devoured by their parasites, 
5 Marsham in Linn. Trans. iii, 26. 
4 See above, pp. 92, 93, 
