224 WASP STUDIES AFIELD 



with her and sometimes laying it down. At last she seemed 

 to stumble upon it, and then turned back to get her bur- 

 den which was nearby. In her confusion by this time, 

 however, she pulled loose from the earth another little clod 

 and used that as a covering for her burrow. Thus it seems 

 that even a little scrap of paper beside the nest so altered 

 the topography as to utterly confuse this wasp. 



Another, which left likewise under provocation, roamed 

 about in the region of her prey for an hour, while we waited 

 at a safe distance, with the camera focused upon her cater- 

 pillar. After a tedious hour we both left in disgust y she 

 without her caterpillar and we without our picture. 



Instances of this sort only substantiate the "place-mem- 

 ory" idea. When she suddenly leaves her prey in the midst 

 of her journey and has no opportunity of studying the land- 

 marks, even though she be in the immediate vicinity, this 

 wasp is unable, or able only with great difficuly, to find her 

 prey. When she does find it, as she occasionally does, we be- 

 lieve it is due merely to her stumbling upon it by chance as 

 she scours the region, and if the same element of chance 

 leads her footsteps one inch to the right or left of it, it is as 

 lost to her as if she were a mile away. It does not seem that 

 scent or even sight plays a very great part at least the 

 sight of the object of her search although probably she 

 must depend upon the visual sense in establishing her place- 

 memories. It is barely possible that this might have devel- 

 oped a condition of far-sightedness. 



Pictipennis is very select in the choice and treatment of 

 her prey. We have never known her to use more than a 

 single individual for the provisioning of a nest, but these 

 are sleek, fat and meaty, usually of the cut-worm type. Some 

 of them have been identified for us by Dr. Barnes and Dr. 

 McDonnough as Agrostis C. nigrum, and a Hesperid larva 

 Pholisora catullus. Another species often used is identical 



