288 KANSAS UNIVERSITY SCIENCE BULLETIN. 



came out and quickly backed into the nest. Probably she 

 backed in to oviposit in the empty upper cell. She stayed in 

 two minutes, and then went to the field again. In two minutes 

 she had brought a caterpillar. Here I left her for the day. 



The next morning soon after 7 o'clock I was waiting at the 

 door of the burrow. At 7 :35 her head appeared in the door- 

 way. Evidently she had backed into her burrow and spent the 

 night there. She waited there until 7 :48, and then took wing. 

 Her morning's hunt was entirely unsuccessful as far as I 

 observed it. Perhaps the comparative coolness of the morning 

 affected her. She made six successive trips to the field and 

 returned each time without prey. The time required for these 

 trips, respectively, was as follows: 16, 12, 21, 15, 12 and 15 

 minutes. The purpose of her return seemed to be to inspect 

 the nest. After her second trip to the field it appeared that 

 she was about to begin further excavations in her burrow. She 

 carried out three pellets, the removal of each one requiring 

 about a minute. She then returned to the hunt. 



After her sixth "empty-handed" return to her nest I fol- 

 lowed the wasp to the field, to learn, if possible, the cause of 

 her lack of success. She seemed to be in earnest about hunt- 

 ing. She would fly from one mallow plant to another, running 

 over the leaves and stems. Twice she found a caterpillar and 

 struggled with its web, but did not seem able to dislodge the 

 inmate. In one of these instances she worked four minutes 

 trying to tear open a caterpillar's nest before she gave it up. 

 Another time she was successful in dislodging a caterpillar, 

 stung it twice, and then dropped it. She then continued hunt- 

 ing on the same plant, and once actually walked over the pros- 

 trate caterpillar, but did not appear to notice it. After fol- 

 lowing her for twelve minutes I left her. I returned to the 

 nest an hour and a half later and found her closing it. She 

 at once located a new nesting site within a few inches of the 

 first one and began excavations for another nest. By noon 

 and throughout the afternoon she was again carrying caterpil- 

 lars as busily as she had been the day before. Both nests were 

 two-celled. 



0. dorsalis was easy to follow while hunting in a mallow 

 patch. The plants were small and spreading and could not 

 hide her movements. Her flights from plant to plant were 

 short, and she spent considerable time running over each plant. 

 She seldom seemed sensitive to observation, and her large size 



