The Ecology of a Sheltered Clay Bank 171 
the blackberry blossoms, or to rest listlessly upon the 
nearby vegetation. The females moved about with an 
air of hesitation, of uncertainty. All this showed that 
the emergence of this species had probably begun on 
that day, so, judging by the last year’s population, we 
had reason to expect that the next two days would show 
an exodus of great magnitude. Unfortunately, I could 
not be present during the next few days. 
On June 13, a very different type of activity was ap- 
parent. Hundreds of turrets were already completed 
and hundreds of busy mothers were flying in and out of 
their nests. In two weeks wonders had occurred. The 
males had come and gone—not one was to be seen. 
Judging by the progress of the work each activity must 
have been practically simultaneous for the whole group. 
Thus, all nests were in the same stage of construction, 
indicating that the work had begun simultaneously; 
hence probably emergence and mating had occurred 
for all within a day or two. 
The amount of work which they had already done 
was enormous, such as could only have been accom- 
plished by their toiling as they do from sun to sun. At 
5:30 a. m., one day I saw some of them beginning their 
work, and at 7:30 p. m., when it was almost too dark in 
the shadows to find their burrows, they came home and 
crept in. Later in the season they were not so in- 
dustrious early and late on cool or cloudy days. : It is 
their habit to carry water in the gullet, with which to 
reduce the hard yellow clay to workable mud. When one 
takes a bee in a test-tube, it disgorges the water on the 
glass in its futile fury. On one occasion, several bees 
in a test-tube disgorged so much water that they became 
