58 Psyche [April 



several times, finally flying to a tree twenty feet distant. The 

 stone was then replaced on the true nest. The wasp returned, 

 still bearing her prey, tried the false nest as before, but almost 

 immediately went to the right nest and entered. 



This wasp was captured for identification as she was about 

 to complete her nest at 1 o'clock (June 21). 



Nest No. 7. Another Ancistrocerus capra was discovered 

 constructing her nest on the same day at 5 P. M. Two hours 

 later she had made a basal wall of mud, deposited an egg and was 

 resting in the tube. 



During the mud-carrying operations of this wasp, I re- 

 moved the stone which marked her nest and placed it six inches 

 to one side. Returning, she flew directly for a point beneath the 

 removed stone, discovered her error and flew along the wall in a 

 horizontal direction, pausing before another nesting block, 

 similarly located on an adjacent window ledge and similarly 

 marked by a small stone. She hovered in front of this empty 

 nest, still holding the lump of mud she was carrying, then sud- 

 denly made a swift flight perpendicularly from the building? 

 turned and made a bee line for her true nest, which she found 

 without delay. The stone was not immediately replaced, but 

 the wasp on subsequent trips entered her nest without hesita- 

 tion, approaching it, however, in a perpendicular direction, 

 instead of obliquely as she had done before her landmark had 

 been misplaced. When the stone was replaced she continued to 

 enter the nest without confusion. 



The second day of this wasp's activities was extremely hot 

 and humid. I had always believed that such a day would be 

 particularly conducive to work with the wasps, and was surprised 

 to find that this individual responded to the heat in much the 

 same manner as her observer, for she remained in her nest the 

 greater part of the day and brought in only three caterpillars? 

 one in the early morning and two in the late afternoon. The 

 following day (June 23) heavy clouds kept off the heat of the sun 

 during the morning so that by ten o'clock four caterpillars had 

 been stored. A half hour later the rim of the closing partition of 



