244 Annals Entomologiacl Society of America [Vol. IX, 



For some reason the group dwindled from this time on, and 

 •each night a smaller number came back; perhaps the disturbance 

 of the cow's intrusion drove part of them away. Up to the end 

 of July from 2 to 4 were usually found asleep at night; these 

 faithful ones were always on the same twigs near the original 

 roost. 



A second burned area was found some three hundred feet 

 away, similar in all respects to the first and surrounded by green 

 vegetation. Around the periphery of this burned patch no 

 bees were found, but in the center, on a cluster of five brown 

 stems, 14 bees were at rest. Most of them were huddled to- 

 gether in groups of 2 to 7. All were at rest on or near the tops 

 of the plants, head downward, with the characteristic ventral 

 ■curl of the abdomen. Here again the bees had chosen this dull 

 spot which so delicately suited their coloration, and away from 

 the edge of the patch. In the early twilight many of the bees 

 were busy cleaning their necks, eyes and antennae with their 

 front feet. No others were found anywhere in the vicinity. 



This group of bees, about 14 to 16 in number, also came 

 repeatedly until the end of July, when the group dwindled and 

 suddenly and mysteriously disappeared. By marking the 

 insects we assured ourselves that the same individuals came 

 back night after night. 



In the centre of a thick clump of white snakeroot almost 

 ready to bloom was a dried stalk of the same plant from last 

 year. Crowded together upon the head of this one dead plant 

 were 40 of these bees. All were head downward, in precisely 

 the same position as described before, and were quiet excepting 

 for movements of the legs when cleaning themselves or kicking 

 their neighbors. They were thus settled for the night although 

 the sun was still well up at 6 o'clock on an early August evening. 

 Here is another case of bees selecting dried plants of their 

 own color. 



Alongside the green plants bearing Priononyx atratiim men- 

 tioned before was a dried stem; this too was the chosen resting 

 place of 4 of these bees, although green plants were much more 

 abundant all about. 



On August 4, 19 bees were still at rest on some bushes at 

 8 a. m., when the whistle of a passing train caused some of them 

 to fly away. It must have been about their normal hour of 

 rising, for within the next three minutes all the others departed 

 singly for their days work. 



