II FOOD OF INSECTS 39 



not involve any marked degree of cleverness, nor is it 

 difficult to comprehend. But by what power does she 

 become aware of the presence of a suitable host inside 

 fruit or the branch of a tree, and completely concealed 

 from sight ? She discovers the exact spot where it 

 lies hid, and, with her long ovipositor,* pierces 

 through the bark, or solid wood, or skin, as the occa- 

 sion requires, driving her eggs into closest contact with 

 the selected victim. When one ability fails to be use- 

 ful under the circumstances of life, another is believed 

 to come into prominence to supply its place. Her 

 eyes * cannot assist her to this knowledge, which has 

 been attributed to the sense of smell, aided perhaps 

 by that of hearing, but these matters await elucidation. 

 The mother's capacity, as it were, to gauge the appe- 

 tites of her young is equally extraordinary creatures 

 of which she can know nothing. She is no miserly 

 caterer, but is ever careful to provide them with nourish- 

 ment in quantity enough and to spare. A large parasite 

 lays only a single egg at a time, because its larva is 

 capable of consuming the recipient's entire substance ; 

 had it been accompanied by brother-larvae, they must 

 all have come to grief by starvation. If a somewhat 

 smaller parasite avails itself of a great host, then two or 

 three eggs are introduced ; and should the ichneumon * 

 be very diminutive, the host may receive as many as 

 fifty or sixty, or more. But these insects seem in- 

 capable of altering their proceedings according to the 

 occurrence of events. Each follows the same plan for 

 generation after generation, without variation. If a 

 large parasite came across a bigger host than it had 

 ever met before, it would bestow only a single egg 



