The Hunting Wasps 



conditions in which it acts. This is the in- 

 variable antithesis of instinct. 



A Bembex, actively engaged in feeding 

 her larva, leaves the burrow. She will re- 

 turn presently with the produce of the chase. 

 The entrance is carefully stopped up with 

 sand, which the insect has swept there back- 

 wards before going away; there is nothing to 

 distinguish it from other points of the sandy 

 surface ; but this does not trouble the Wasp, 

 who finds her door with a skill which I have 

 already emphasized. Let us devise some in- 

 sidious plot and change the conditions of the 

 locality in order to perplex the insect. I 

 cover the entrance with a flat stone, the size 

 of my hand. The Wasp soon arrives. 

 The great change effected on her threshold 

 during her absence appears to cause her not 

 the slightest hesitation; at least, the Bembex 

 at once alights upon the stone and tries, for 

 an instant, to dig into it, not at random but 

 at a spot corresponding with the opening of 

 the burrow. The hardness of the obstacle 

 soon dissuades her from her enterprise. 

 She then runs about the stone in every direc- 

 tion, goes all round it, slips underneath and 

 begins to dig in the exact direction of her 

 dwelling. 



338 



