no. 2173. A REVISION OF THE B EM B WINE WASPS— PARKER. 137 



which it gathers up from the surface of the sands, instead of capturing 

 and paralyzing living insects by stinging, as do other wasps of similar 

 habits. The food is consequently exceedingly variable, but May-flies 

 and midges were most used, probably because of their abundance on 

 the sands and the consequent ease with which they could be secured. 



When the wasp is storing her nest with food it is possible to induce 

 her to take into it insects placed at the entrance while she is inside. 

 In this manner I repeatedly succeeded in having newly-killed May- 

 flies, midges, house-flies, and stable-flies taken into the nest. If a 

 May-fly was disabled but still possessed of life enough to move its legs 

 or wings the wasp invariably appeared afraid of it and refused to touch 

 it when it was placed at the mouth of her burrow. I did not observe 

 a single case in which a wasp attacked and carried off a living unin- 

 jured insect, but they did attack and carry off house-flies, stable-flies, 

 and even May-flies that I cast upon the sand after having disabled 

 them to such an extent that they could not fly. In seizing such an 

 insect the wasp appears to sting it, but of this I can not speak with 

 certainty. When one of these insects was seized the wasp invariably 

 bent her abdomen forward, bringing the tip into contact with her 

 victim, thus going through the performances that would be incidental 

 to stinging; but this same performance may sometimes be seen when 

 the wasp seizes a dead and dried insect lying on the sand. I am of 

 the opinion, however, that the instinct to sting still remains, and that 

 whether the prey be a disabled or a dead insect the wasp uses her sting 

 upon it. 



One of the most interesting questions met in this investigation is 

 "How do these wasps find the entrance to their burrows?" The 

 results of my observations force me to conclude that they do so 

 through the sense of smell or some power similar to smell. When the 

 wasp has completed her burrow and deposited an egg therein she 

 closes up the entrance by digging the sand into the mouth of the bur- 

 row until it is filled. Not content with this she smooths the sand 

 about the entrance and then beginning near it she proceeds outward 

 first in one direction and then in another, throwing the sand behind 

 her and scattering it loosely over the spot where the mouth of the 

 burrow is concealed. When she has finished there is absolutely not 

 a trace of the burrow to be seen. Nevertheless when the wasp returns 

 two or tliree days later she is able after searching about over the sand 

 for a little while to dig down directly into the mouth of the burrow as 

 readily as if before filling it up she had inserted a stake into it to guide 

 her in opening it again. She can do this no matter how greatly the 

 appearance of the surface has been changed by wind, rain, or the 

 trampling of animals since the time when she so carefully concealed 

 the entrance. I repeatedly altered the appearance of the sand about 

 the entrance to the nest between the visits of the wasp while she was 

 busied in bringing in food, but I never succeeded in confusing her, 



