264 A BOOK OF INSECTS 



paring the ball which is destined to contain her egg. 

 This ball, which is fashioned during the autumn in a 

 subterranean nursery, is quite distinct from those which 

 the insect prepares in the springtime for the gratification 

 of her own appetite. The necessary materials having been 

 collected, the Scarabaeus settles down to her task. " The 

 first tiling to do is to select very carefully, taking what 

 is most delicate for the inner layers, upon which the larva 

 will feed, and the coarser for the outer ones which merely 

 serve as a protecting shell. Then, around a central hollow 

 which receives the egg, the materials must be arranged 

 layer after layer, according to their decreasing fineness 

 and nutritive value ; the strata must be made con- 

 sistent and adhere one to another ; and finally, the bits 

 of fibre in the outer crust, which has to protect the whole 

 thing, must be felted together. How can the Scarabaeus, 

 clumsy and stiff as it seems, accomplish such a work in 

 complete darkness, at the bottom of a hole so full of pro- 

 visions that there is barely room to move ? . . . Explain 

 who can this miracle of maternal industry." Nor is this 

 all, for Fabre found that the mother beetle regurgitates 

 a partially digested paste which is added to the layer 

 immediately surrounding the egg, thus providing an easily 

 assimilated first meal for her offspring. 



Still more remarkable are the habits of those insects 

 which, by their instinctive preparations, enable their young 

 to live at the expense of others. The female ichneumon 

 lays her eggs either in or upon the body of another insect, 

 usually a caterpillar, which is thus doomed to become the 

 "host" upon whose substance the parasite larvae will fatten. 

 One small Braconid ichneumon {Microgaster glomeratus) 

 lays its eggs in the caterpillars of the large -white butterfly 

 — usually in such numbers that when the caterpillar is 

 full-grown its skin is literally packed with the alien grubs, 



