ISELY: EUMENID^ OF KANSAS. 271 



mately every fifty seconds. Later in the afternoon she was 

 much slower. She was collecting earth when I first observed 

 her, and made seven attempts before she succeeded in alight- 

 ing with her load. She backed out part way in seven minutes, 

 then disappeared again. Five minutes later she came out and 

 started for a second load of earth. In four minutes she suc- 

 ceeded in alighting with a load. She came out and backed in. 

 Six minutes later she again began work. It was fifteen min- 

 utes before she succeeded in landing. She remained in the 

 nest only four minutes. The next successful trip required 

 twenty minutes of struggle. When I left she was still battling 

 with the wind. 



Odynerns arvensis Saussure. 



Odynerus arvensis is one of the most numerous of the 

 eumenids in western Kansas. I collected it in every county 

 covered by the survey, except the first one. It was common 

 throughout the summer, being taken regularly between June 26 

 and September 6. It was most readily found in lowland fields 

 and pastures or near water. 



Along the edges of streams, throughout the entire summer, 

 this wasp was by far the most conspicuous of the Odyneri. 

 At crossings for live stock on streams, at the edges of sand or 

 mud bars, where the insect can walk directly to the water's 

 edge, I always expected to find an assemblage of these wasps. 

 Where the approach to water in a stream was in any way 

 abrupt I never found them; like 0. papagomm. 0. arvensis 

 never floats on running water. However, they were common 

 floating on water in cattle tracks at crossings or in small pools. 

 At these situations wasps were constantly coming and going. 

 They were the busy females getting water for nest-building. 



On sandy beaches along watercourses I sometimes observed 

 dozens of wasps, also of this species, apparently playing in the 

 sunshine. In contrast to those just described, they seemed to 

 have no particular business except to chase each other up and 

 down the beach. They were very wary and active, like sand 

 robber flies, and were hard to take with a net. I collected 

 fourteen of these idlers one afternoon in Rooks county, and 

 without exception they proved to be males. They could not 

 have been waiting there for females to come for water, for 

 nowhere along that sandy beach was there a place frequented 



4-Univ Sci. Bull . V, 1 VIII. No. 7. 



