Ecological and Behavior Notes 27 



Two years later, July 2, 1920, 1 revisited the same spot 

 and was gratified to find the same performance going on 

 in precisely the same way. The wasps had evidently 

 emerged from the ground at that place and were in high 

 spirits in the dance. They were a riotously noisy lot, 

 emitting almost constantly a bee-like buzz when in flight, 

 and the greater part of them were in flight all the time. 

 They danced and cavorted to and fro, in and out, up and 

 down, over this sparsely-covered spot Occasionally a 

 few would rest for a time on the grey earth or on a green 

 leaf, or on the trunk of the tree. Most of the flight 

 occurred within six inches of the ground; occasionally 

 one would dash off for a moment to a higher altitude, but 

 the swarm in general kept pretty steadily to about that 

 level, and they never ventured more than a few inches 

 above that. When in flight, small groups of from two to 

 four were seen waltzing about one another in circles; 

 often one chased another for a short distance with great 

 swiftness. Sometimes a pair would tumble to the ground, 

 struggle and separate, but I have so far failed to see if 

 this was actual copulation. There were about fifty wasps 

 present in this area, and all were participating in the 

 dance. It appeared that they had recently emerged here ; 

 no evidence of their digging could then be detected. The 

 dance was observed for about an hour, which was as long 

 as I could remain at high noon. This species was later 

 seen on the buck-brush flowers at Wesco, Mo., on August 

 1. 



Tachytes obscurus Cress. [S. A. Rohwer]. Several 

 were seen on the sandbar at Wickes, Mo., sometimes 

 entering crevices. 



Tachytes mergus Fox. [S. A. Rohwer]. These wasps 

 were on the river sandbar on September 6, 1919, actively 

 running about and often entering holes which appeared 

 to be those of Microhembix monodonta. 



Tachytes obductus Fox. [S. A. Rohwer]. Seen enter- 

 ing holes in the sand at Wesco, August 1. 



