I.] METAMORPHOSES OF INSECTS. u 



the insect, and turn into chrysalides. Almost every 

 kind of insect is subject to the attacks of these little 

 creatures, which are no doubt useful in preventing 

 the too great multiplication of insects, and especially 

 of caterpillars. Some species are so minute that they 

 actually lay .their eggs within those of other insects 

 (Figs. 15, 1 6). These parasites assume very curious 

 forms in their larval state. 



But of all the Hymenoptera, the group containing 

 the ant, the bee, and the wasp is the most interesting. 

 This is especially the case with the social species, 

 though the solitary ones also are extremely remark- 

 able. The solitary bee or wasp, for instance, forms a 

 cell generally in the ground, places in it a sufficient 

 amount of food, lays an egg, and closes the cell. In 

 the case of bees, the food consists of honey ; in that 

 of wasps, the larva requires animal food, arid the 

 mother therefore places a certain number of insects 

 in the cell, each species having its own special 

 prey, some selecting small caterpillars, some beetles, 

 some spiders. Cerceri's bupresticida, as its name 

 denotes, attacks beetles belonging to the genus Bu- 

 prestis. 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 corruption. 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 ; consequently, when the young larva leaves 



