264 KANSAS UNIVERSITY SCIENCE BULLETIN. 



When hunting, this wasp sometimes runs quite rapidly over 

 the flower heads. More often her progress is very slow, as she 

 peers carefully among the disk flowers. 



I was anxious to observe the wasp's attack upon her prey 

 more closely, and thought to bring this about by artificial 

 means. With nails I pinned two sunflower heads in the midst 

 of a colony. Upon these sunflowers I placed about a dozen 

 caterpillars upon which 0. papagormn preyed. There were 

 the same species of caterpillars for which the wasps had been 

 searching so diligently in the field, within a few inches of the 

 thresholds of the wasps' storehouses ; but my efforts were 

 fruitless. Not a caterpillar was attacked. Not only did the 

 wasps ignore the caterpillars I had placed there for their con- 

 venience, but they seemed even to be wholly unmindful of the 

 sunflowers. They flew directly to and from their nests as if 

 nothing had been changed in the site of their colony. 



The caterpillar is carried ventral side upward. With her 

 mandibles the wasp grasps the caterpillar's neck. One pair of 

 legs are also used in holding the caterpillar's body under 

 her own. 



Upon reaching her nest, the wasp with her mandibles and 

 legs quickly moves the caterpillar, head first and ventral side 

 upward, into the tube. Then she follows it in. As far as I 

 have observed, the wasp always pushes the caterpillar with 

 her head. After the caterpillar is stored she backs out and 

 again goes on the hunt. 



Storing caterpillars was not always an easy matter. On 

 one occasion I saw a wasp have considerable difficulty in push- 

 ing a caterpillar ahead of her into the tube. The caterpillar did 

 not seem to be thoroughly paralyzed, for as soon as it was 

 pushed ahead of the wasp it would try to curl up or hold to 

 the sides of the tube. After several attempts the wasp started 

 it into the burrow. About four minutes later she backed out, 

 bringing the unruly caterpillar with her. She alighted on the 

 side of the cliff and vigorously bit its neck and first thoracic 

 segment. After belaboring it for about a minute she pushed 

 it in again, this time with no apparent trouble. 



Of all the caterpillars that I took from cells, not one that I 

 noticed was dead. Even those that had been in cells so long 

 that nearly all of their partners had been devoured by the wasp 

 grub still responded to stimulation. The caterpillars were 

 paralyzed with varying degrees of success. Some would only 



