Modification by Experience 263 



the plants, as if she were making a careful study of the 

 region. On leaving the nest a second time she omits this 

 process and flies straight away. A similar "locality sur- 

 vey" is made by hive bees and by social wasps. Secondly, 

 the Peckhams argue that if the wasp does not remember 

 her nest by landmarks, it ought to make no difference to her 

 when the surroundings are altered in any way. They found, 

 however, that a wasp of one species could not discover her 

 nest when a leaf that covered it was broken off, but found 

 it again without trouble when the leaf was replaced. Another 

 wasp abandoned the nest she had made for herself with much 

 labor, because the Peckhams, to identify the spot themselves, 

 drew radiating lines from it in the dust. A third argument 

 against the existence of a special sense of direction is the fact 

 that wasps sometimes are unable to find their nests. In one 

 case the Peckhams dug up the nest of a wasp and she made 

 another five inches away. After an absence of three hours the 

 wasp returned, and seemed to be puzzled as to whether the old 

 spot or the new one were the place of her nest. " At first she 

 alighted upon the first site and scratched away a little earth, 

 and then explored several other places, working about for 

 twelve minutes, when she at last found the right spot." Simi- 

 larly, when a wasp that was carrying her prey left it for a few 

 moments to go to the nest, as many of them do, apparently to 

 see that all is right there, if any of the surrounding objects 

 were altered she often had great difficulty in finding the prey 

 again. On one occasion a wasp of another species dug its 

 nest in the midst of a group of nests of the Bembex wasp. 

 These latter are usually dug in a wide bare space of earth 

 which has no vegetable growth to serve as a landmark. When 

 the intruder had finished her nest, it looked just like the Bem- 

 bex holes. She went away, secured a spider, and when she 

 returned she could not find her nest. " She flew, she ran, she 



