CLASSIFICATION AND ORIGIN OF INSECTS 1409 



spiders. Cerceris bupresticida, as its name denotes, 

 attacks beetles belonging to the genus Buprestis. 

 Now if the Cerceris were to kill the beetle before 

 placing it in the cell, it would decay, and the young 

 larva, when hatched, would find only a mass of cor- 

 ruption. On the other hand, if the beetle were 

 buried uninjured, in its struggles to escape it would 

 be almost certain to destroy the egg. The wasp has, 

 however, the instinct of stinging its prey in the centre 

 of the nervous system, thus depriving it of motion, 

 and let us hope of suffering, but not of life; conse- 

 quently, when the young larva leaves the egg, it finds 

 ready a sufficient store of wholesome food. 



Other wasps are social, and, like the bees and ants, 

 dwell together in communities. They live for one 

 season, dying in autumn, except some of the females, 

 which hibernate, awake in the spring, and form new 

 colonies. These, however, do not, under ordinary 

 circumstances, live through a second winter. One 

 specimen which I kept tame through one spring and 

 summer lived until the end of February, but then 

 died. The larvae of wasps are fat, fleshy, legless 

 grubs. When full-grown they spin for themselves 

 a silken covering, within which they turn into chrys- 

 alides. The oval bodies which are so numerous in 

 ants' nests, and which are generally called ants' eggs, 

 are really not eggs, but cocoons. Ants are very fond 

 of the honey-dew which is formed by the Aphides, 

 and have been seen to tap the Aphides with their an- 

 tennae, as if to induce them to emit some of the sweet 

 secretion. There is a species of Aphis which lives on 

 the roots of grass, and some ants collect these into 



