isely: eumenid/e of Kansas. 275 



river for water. This trip took from one minute and forty 

 seconds to two minutes. After the tube was half an inch high 

 she began dropping pellets a few inches from the burrow. 



I had watched her from 7:50 A. M. until 8:20 A.M. As I 

 had other work for the morning, I left her. When I returned 

 about noon she had deserted the nest. This observation was 

 made July 24. The building of this nest was fairly typical, as 

 far as I observed, of the ne.st-building of the species. 



When the nest is stored the cells are sealed, the tube is torn 

 down with the aid of several loads of water, and is tamped 

 into the burrow. Loose earth around the burrow is also pushed 

 into it until it is entirely filled. This process I observed but 

 once. 



Four species of caterpillars — three pyralids and one noctuid 

 — ^were found in the nests of 0. arvensis that I opened. I did 

 not find more than a single species of caterpillar stored in one 

 nest, or even taken in one locality. On the other hand, with 

 each change of locality there was a change in the caterpillar 

 prey. One of the caterpillars upon which this wasp preys, 

 Loxostege sticticalis, is of considerable economic importance. 



The caterpillars in every instance were alive in the nest 

 when I opened it. 0. arvensis was often very careless about 

 the state of mobility in which she left her prey. Once several 

 caterpillars actually climbed the sides of the glass vial in which 

 I had collected them, worked their way through the cotton 

 stopper, and were crawling actively about on the inside of my 

 collecting bag. 



All of the caterpillars which this wasp collected were rather 

 slender. All were larger than the wasp, varying from 16 to 

 18 mm. I never found more than seven caterpillars in a cell. 



A black Odynerus storing caterpillars in her nest I observed 

 in Norton county, August 22. Mr. Williams had found this 

 wasp's tube in a small open space on a fallow hillside, and 

 called me to see it. I waited twenty-five minutes before the 

 owner of the nest appeared with a caterpillar. She deposited 

 it quickly, backed out of the nest, and again went to the field. 

 In thirty-five minutes she returned with a second caterpillar. 

 I then interrupted the proceedings by taking the wasp and 

 opening the nest. 



Her manner of entering the nest with the caterpillar differea 

 somewhat from any of the others of this genus that I have 

 observed. She flew to the tube and rushed into it at once. 



