NOTES 



NOTES ON THE BEHAVIOR OF CERTAIN 

 SOLITARY BEES 



PHIL RAU AND NELLIE RAU 



Colletes compactus 1 



The September afternoon was bright and sultry, with a tem- 

 perature of perhaps 85°, as we trudged up a deep little valley 

 between heavily wooded hills, where a tiny brook ran away from 

 a spring. As we stepped over the stream, the hum and blurr 

 of swarming insects attracted us. There at the side of the 

 water was a swarm of Colletes bees, perhaps two hundred in 

 number, buzzing, flying, wheeling, dancing, weaving in and out, 

 all in a chosen spot a few inches above the pebbles at the water's 

 edge, and in an area about two feet across. The excitement was 

 riotous, dancing and mating, dancing and mating. The males 

 were far in excess of the females, apparently in about the pro- 

 portion of three or four males to one female. The females were 

 not so active as the males, but sat down more often upon the 

 rocks as if in quiet and meek anticipation of attention. And 

 usually they rested only a few seconds before their mates ar- 

 rived, often from two to five males struggling together for the 

 possession of one female. I am not sure whether the female's 

 deliberation was of psychological or physiological causes; mat- 

 ings were not seen to take place on the wing, but she was of 

 heavier build than the male and also was frequently laden with 

 pollen; this may have hindered her participation in the merry 

 dance. They were so intent upon their frolic that we could 

 pick them up easily with the forceps, and our presence scarcely 

 disturbed them; when we stepped into the very midst of the 

 swarm they scattered a little — of necessity — but returned and 

 concentrated on the same spot as soon as we removed ourselves. 



1 We are indebted to Mr. J. C. Crawford for the identification of the three species 

 herein mentioned. 



