276 KANSAS UNIVERSITY SCIENCE BULLETIN. 



dragging the caterpillar under her body, not stopping to push 

 it ahead of her. Her method of carrying the caterpillar, its 

 ventral side up, the wasp's mandibles grasping the caterpillar's 

 neck, is similar to that of others of this genus. This was the 

 only time that I observed the storing of caterpillars. 



In this cell I found three very lively caterpillars. I also 

 found an egg suspended from the cell roof, as far as possible 

 from the entrance. Although this egg was suspended, it was 

 hanging, not above the caterpillars, but among them. Had 

 two or three more caterpillars been added they would have 

 been piled above the egg. I assumed that in this case oviposi- 

 tion had taken place before the storing of the cell had begun. 

 At least I had seen two of the three caterpillars stored, and 

 ovi position had not taken place while I was there. I found 

 the egg of this wasp on one other occasion. It was suspended 

 from the roof of the cell as far as possible from the entrance. 

 I had not seen the egg- until several caterpillars had been re- 

 moved, but the cell was so full that it must have hung among 

 them. This cell had been fully stored before I found it. 



This wasp may not always be active from the time her nest 

 is begun until it is finished. The wasp with the celled nest, 

 previously described, gave no sign of industry during the time 

 I waited before her nest, which extended at intervals through 

 three days. She visited the nest occasionally, but brought no 

 load. On one occasion she started, apparently, to enlarge her 

 nest, bringing out three pellets in one minute and forty seconds. 

 After dropping the third pellet she flew away. When I opened 

 the nest I found the wasp with her head in the entrance of the 

 one empty unsealed cell. 



The five closed cells were completely ravaged by a little 

 brown ant (Solinopsis sp.). A few caterpillars' skins were 

 left in one of the cells, but the others were empty except for 

 the ants. This is .the only suggestion of an insect foe of 

 O. arvensis that I noted except a cuckoo bee that I dug out of a 

 nest in Ness county. I was unable to take it, and so can not 

 give the species. 



As far as I observed, 0. arvensis never had any trouble find- 

 ing her way to her nest. She never seemed to be sensitive to 

 observation. 



