EXPERIMENT ON THE SENSE OP DIRECTION OF CER- 

 CERIS FUMIPENNUS. 



The Sense of Direction of animals, particularly of Ants, Bees, 

 and Wasps, is a subject which has engaged the attention of many 

 naturalists. From my own observations on social and solitary wasps 

 I incline to the opinion tliat these are guided mainly by sight in 

 which familiar objects in tl:e environment of their nests are im- 

 portant factors. 



A rather decisive evidence of the important role played by trees, 

 bushes and other objects in the orientation of insects is afforded by 

 the actions of one of my friends, Cerceris fumipennis. On October 

 24th I discovered her bearing a weevil ( Chonotrachelus neocrataege) 

 into her nest, which was situated on the edge of a five-foot embank- 

 ment just under a bush some two feet high. The next day I re- 

 turned, cut the bush off at the roots and placed it three feet to the 

 right. Soon fumipennis, too, returned and flew, not to her nest 

 but to the bush which I had placed to one side. After discovering 

 her mistake she flew away to get another start, came down again 

 from between two trees and flew to the bush. Since she repeated 

 this performance at least a dozen times without finding the nest, it 

 is safe to conclude that it was the bush which directed her flight. 

 Moreover, the wasp always flew down from the same direction, show- 

 ing that earlier in her course she was directed by other objects, es- 

 pecially trees. This latter observation I have several times made 

 on wasps whose nests I destroyed before the owners had completely 

 stored them. 



As a matter of fact, the power of finding their way is not so per- 

 fect as one might be led to suppose. Many spider-ravishers have 

 great difficulty in finding the spiders which they hid or hung up 

 while digging their nests. I have seen individuals of Bemhex tex- 

 anus and Monedula Carolina so far lose track of their nests as to 

 fail entirely to find them again. 



In view of these and other facts I should agree with the Peckhams 

 in the opinion that wasps have no additional sense, the sense of di- 

 rection, in the common acception of the term, nor that they find 

 their way by a process of dead reckoning as Darwin suggested, but 

 that they find their way by a detailed familiarity with objects near 

 the nest and by a general acquaintance with the locality in which 

 they pass their lives. 



