XII THE IGNORANCE OF INSTINCT 175 



rolls to the bottom, and when the Sphex returns 

 and does not find it where she left it, she must 

 hunt for it, sometimes in vain. If found, there will 

 be a difficult climb, which, however, does not prevent 

 her leaving it once more on the perilous slope. 

 The first of these repeated visits to her cell is easily- 

 explained. Before bringing her heavy load she is 

 anxious to make sure that the entrance is clear, 

 and that nothing will hinder her carrying in the 

 prey. But what is the use of her other visits, repeated 

 so speedily one after another ? Are the Sphex's 

 ideas so unstable that she forgets the one just made, 

 and hurries back a moment later, only to forget 

 that she has done so, and so on ? It would indeed 

 be a slippery memory where impressions vanished 

 as soon as made. Let us leave this too obscure 

 question. 



At length the game is brought to the edge 

 of the well, its antennae hanging into the mouth, 

 and there is an exact repetition of the method 

 used by S. flavipennis, and, though in less striking 

 conditions, by S. occitanica. She enters alone, 

 reappears at the entrance, seizes the antennae, 

 and drags in the Acridian. While she was within I 

 have pushed the prey rather farther off, and have 

 always obtained precisely the same result as in 

 the case of the huntress of crickets. In both 

 Sphegidae there was the same persistence in plung- 

 ing into their burrows before dragging down their 

 prey. We must recollect that S. flavipennis does 

 not always allow herself to be duped by my trick 

 of withdrawing the insect. There are elect tribes 

 among them, — strong-minded families, — who after a 



