AFFECTION OF INSECTS FOR THEIR YOUNG. 197 



veyor 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 putrefying would 

 destroy the enclosed egg, or the young one which springs from it. But 

 when larvae 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. 1 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, Sphedna^, 

 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 with a mass of pollen or honey collected with unwearied assiduity 

 from a thousand flowers. As soon as the grub is hatched, it finds itseff 

 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 number of wild bees, however (those of the genera 

 Nomada, Melecta, &c.) t 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 

 deposited their eggs and the necessary supply of pollen moistened with 

 honey 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 storgc 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 



i Keaura. vi. 252. 



8 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 Sphecidce, Pompilidce, Bembecidce, &c. 



o 3 



