242 PHIL RAU 



blue wasp, Chalybion caeruleum, returned to it. She examined 

 the spot very carefully for about thirty minutes. When she 

 flew out I replaced the nest, but before doing so I removed five 

 spiders from the new cell which she was engaged in filling. She 

 returned, still with the green spider which she carried when 

 first she missed her nest. She hovered about on the nest very 

 nervously for some minutes and entered the cell five or six times 

 and seemed greatly excited and puzzled; she re-examined the 

 whole nest again and again and re-entered the cell many times, 

 and finally after thus hesitating for about forty minutes she 

 soared away with an indignant buzz, without even depositing 

 her new prey. 



While she was gone I removed six spiders from another cell 

 of her own nest (this cell was at the back of the nest, against 

 the wall, so one side was open, but when the nest was returned 

 to its position against the wall no mutilation was apparent to 

 confuse the owner), and placed them in the new cell. She soon 

 returned and set about promptly to remove these six spiders 

 one by one and either dropped them after a flight of a few inches 

 from the nest or carried them quite outside the barn. 



Apparently she had had enough of this cell, for after a few 

 minutes she flew in with a pellet of mud and began to seal it 

 up, empty. 



Exp. 4. A Pelopoeus mother was busily engaged in stocking 

 her new cell. I plundered the nest of a blue wasp near by and 

 placed six spiders from it in the new cell. The owner returned 

 with a spider of her own, placed it in the cell on top of the stolen 

 booty, pushed the whole in with her head and rammed it down 

 about six times as though it were all her own, then flew out, 

 returning almost at once with a pellet of mud with which she 

 sealed the cell, and reinforced it with four or five more such 

 balls. All this she did with an air of peace and satisfaction in 

 work well done. 



If some females can by some sense detect the spiders which 

 have been caught and paralyzed by another of her kind, and 

 express such resentment toward their presence, how much more 

 strange it is that this one does not seem to be aware that part 

 of her prey had been handled by a foreign species entirely, 

 besides myself, or if she does know it, she cares not a whit. 



