292 KANSAS UNIVERSITY SCIENCE BULLETIN. 



Of thirty-seven cells opened at least eighteen did not produce 

 0. dorsalis. In one of these eighteen cells I found the pupa of 

 a bombyliid, probably of the genus Anthrax. In one of these 

 cells was an empty pupal case, probably of a chrysidid. In the 

 walls of two other cells I found tachinid flies. These flies had 

 endeavored to break their way out of the cells by burrowing 

 into the wall, and had perished. In the remaining fourteen 

 cells were found many dipterous pupal cases, perhaps also 

 tachinid. These flies may have been parasitic upon the cater- 

 pillars stored, but at any rate they prevented the development 

 of the wasps. 



I opened a two-celled nest in Rooks county in the upper cell 

 of which were seven recently stored caterpillars ; in the lower 

 cell were only caterpillar skins and many almost minute spring- 

 tails. I once took a mutillid (Miitilla simillinia) in a nest. 

 The cuckoo bee (Chrysis intrica) was so closely related to the 

 nesting activities of 0. dorsalis that I shall deal with it sep- 

 arately. I have taken a large robber fly (Deromya sp.) carry- 

 ing this wasp. 



Chrysis intrica always attended the excavation and storing 

 of the nests of O. dorsalis. I never watched the domestic 

 activities of this wasp but that a cuckoo bee was present. The 

 Odynerus could scarcely begin digging before one of these 

 ubiquitous parasites would appear. Chrysis would wait pa- 

 tiently, facing the nest, on the tip of a grass blade a few inches 

 away. It manifested its interest in the proceedings by dart- 

 ing into the burrow occasionally, and then hurriedly resuming 

 its position on the grass blade. Sometimes it would even enter 

 the burrow when the wasp was within. Often there would be 

 two or three cuckoo bees waiting around one burrow. 



Ordinarily the wasp and the cuckoo bee seemed to pay little 

 attention to each other. The cuckoo bee was nearly always 

 motionless in the wasp's presence. When the wasp did dash at 

 the cuckoo bee it would take wing or drop into the grass. The 

 wasp was never successful in catching it. When the wasp 

 would go back to work the cuckoo bee would resume its posi- 

 tion. Three times I saw 0. dorsalis carry Chrysis out of her 

 nest with her mandibles ; but each time she dropped the para- 

 site like a pellet of earth, and left it apparently unharmed. 



On one occasion Mr. Williams and I watched Chrysis break 

 into a nest of 0. dorsalis after it had been sealed up. The wasp 

 had closed its burrow entirely and had gone for water with 



