The Ecology of a Sheltered Clay Bank 255 
lucky ones in this case may have been the least fit to per- 
petuate the race? In the activities of the turret-build- 
ing bees also, we find wet or dry weather an important 
factor in their nest building. In dry years, the turrets 
are almost entirely omitted and in the case of A. abrupta, 
when for the scarcity of water, much labor is put into 
hard digging, the number of young is diminished. 
(e) Relation of inhabitants to plant life. 
At first thought, one sees but little relation between 
the plant and the animal life of the bank. The vegeta- 
tion about the base of the bank, scanty as it was, har- 
bored numerous insects, such as small beetles, beetle 
larvae and caterpillars, which sometimes dropped into 
the ant lion pits. The grass-carrier wasp gathered grass 
for her nest; the mining bee, the carpenter bee and the 
Halictus went to the plants for nectar and pollen. The 
caterpillar wasps A. fulvipes visited the plants for their 
nectar and their caterpillars; the Trypoxylon and the 
Tachysphex wasps went to the vegetation for their spl- 
ders and grasshoppers respectively. As we have re- 
lated before, the flowers of the wild morning glory served 
so well as bachelor quarters for the males of the white- 
banded bee that the females were obliged to fight for 
even a chance to harvest the pollen from the flowers. The 
bees came in from the surrounding vegetation bring- 
ing pollen of various colors—yellow, orange, white, or 
light green. One often found against the side of the 
bank splashes of this pollen which had been lost in their 
homeward flight. 
For some time I suspected an intimate correlation 
between the dates of the persimmon blossoms and the 
emergence of the Anthophora bees. In the spring of 
