AFFECTION OF INSECTS FOR THEIR YOUNG. 197 
yeyor should not be omitted, namely, that the number of grubs laid up is 
not always the same, but is exactly proportioned to their size, eleven or 
twelve being stored when they are small, but only eight or nine when 
larger. With respect, however, to the caution of the wasp in selecting 
full-grown grubs and conveying them uninjured to her hole, a satisfactory 
explanation may be given. If those that are but partly grown were chosen, 
they would die in a short time for want of food, and putrefyiag would 
destroy the enclosed egg, or the young one which springs from it. But 
when larva of any kind have attained their full size, and are about to pass 
into the pupa state, they can exist for a long period without any further 
supply. By selecting these, therefore, and placing them uninjured in the 
hole, however long the interval before the egg hatches, the disclosed larva 
is sure of a sufficiency of fresh,and wholesome nutriment.—To prevent the 
possibility of any injury to its egg from the motions or voracity of this 
living prey, the wasp is careful to pack the whole so closely, each grub 
being coiled above the other in a series of rings, and to consolidate the 
earth so firmly above them, that they have not the slightest power of 
motion.t— Those which select more powerful caterpillars, or revenge the 
injuries of their insect brethren by devoting spiders to the destruction they 
have so often caused, take care to sting them in such a manner as, without 
killing them outright, will incapacitate them from doing any injury. 
Zeal and activity in providing for the well-being of their future progeny, 
not inferior to what are exhibited by the tribe of Ichneumons, Sphecina®, 
and mason-wasps, though less cruelly exerted, are also shown by various 
species of wild bees, of which we have in this country a great number. 
Having first excavated a proper cell with a dexterity and persevering 
labour never enough to be admired, they next deposit in it an egg, which 
they cover witha mass of pollen or honey collected with unwearied assiduity 
from a thousand flowers. As soon as the grub is hatched, it finds itself 
enveloped in this delicious banquet provided for it by the cares of a mother 
it is doomed never to behold ; and so accurately is the repast proportioned 
to its appetite and its wants, that as soon as the whole is consumed it has 
no longer need of food ; it clothes itself in a silken cocoon, becomes a 
pupa, and after a deep sleep of a few days bursts from its cell an active 
bee, 
A considerable nuinber of wild bees, however (those of the genera 
Nomada, Melecta, &c.), being unprovided with an apparatus for collecting 
pollen, save themselves not only this labour, but also that of excavating 
cells; and gliding into those in which their more industrious brethren have 
‘leposited their eggs and the necessary supply of pollen moistened with 
heney for food, they also, cuckoo-like, insinuate their own eggs (imitating 
in this respect the carnivorous parasites lately noticed), the larvae from 
which live at the cost of the rightful occupants. 
No circumstance connected with the storge of insects is more striking 
than the herculean and incessant labour which it leads them cheerfully to 
undergo, Some of these exertions are so disproportionate to the size of 
the insect, that nothing short of ocular conviction could attribute them to 
 Reaum, vi. 252. 
2 By this term I would distinguish the tribe of Fossores of Latreille, which the 
French call Wasp-Ichneumons, and which form the Linnean genus Sphex, divisible 
into several families, as Sphecide, Pompilide, Bembecide, &c. 
o3 
