isely: eumenid^ of Kansas. 293 



which to melt some mud for the finishing touches. Suddenly 

 the cuckoo bee, that had been passively waiting for some 

 time, seemed to realize that she was about to be shut out. She 

 flew to the nest, and with little difficulty made an opening in 

 the cap, and disappeared just before the owner of the nest 

 returned. Upon alighting the wasp paused a moment. She 

 saw instantly that something was wrong. She then tore out 

 entirely the cap she had so carefully made, and rushed into the 

 burrow. She soon reappeared with the intruder in her man- 

 dibles, and dropped her on a pile of pellets. She then went 

 for another load of water and again sealed up the burrow. 

 Chrysis took her position on the grass blade and watched the 

 proceedings, but did not again interfere. 



0. dorsalis had a tendency to nest in colonies. I sometimes 

 found an isolated nest, but usually the nests were in small 

 groups, sometimes as many as eight. Usually only two or three 

 wasps would share an open space in a pasture, each wasp 

 digging one or two nests. I never found them in populous 

 colonies like those of 0. }mpagoru7n. 



These wasps sometimes manifested considerable curiosity 

 in each other's work. This characteristic I first noticed in two 

 wasps digging in an open space within three inches of each 

 other. When one was gone for water the other would som_e- 

 times leave its work and inspect the work of the absent party 

 by putting its head into the entrance. . However, I never saw a 

 visitor presuming to enter. The visitor would always hastily 

 return to its own burrow at the near approach of the owner 

 of the inspected burrow. I never saw the females of this 

 species quarrel. 



O. dorsalis was always most active during the heat of the 

 day. On bright sunny days during the nesting season the wasp 

 was apparently busy from eight o'clock in the morning until 

 near sundown. 



0. dorsalis seemed tabe the most cautious of all the members 

 of this genus about floating upon water. Some individuals 

 would float upon pools, but never upon running water. On a 

 gravel bar on the Solomon river I watched one of these wasps 

 come for water. She would alight about six inches from the 

 water's edge and would walk out to it. When on water, or at 

 work elsewhere, 0. dorsalis always kept its wings spread and 

 raised at an oblique angle from the thorax, ready to take flight 

 at any instant. 



