The Ecology of a Sheltered Clay Bank 257 
but this, too, occurs, and often to a much greater extent 
than we usually suspect. During this study at the bank, 
I have often picked up dead and enfeebled insects. Not 
all the Chalcids fell prey to the spiders and ant lions; 
I have removed hundreds from the crevices where they 
had crept in to die. Many mining-bees were picked up 
dead or limp at the end of their season and many more 
were pulled out of their burrows. The cuckoo-bees were 
picked up dead, too—and what enemy could wound a 
cuckoo-bee in its thick armor? The blister-beetles, Hpi- 
cauta marginata, dropped dead from the plants near the 
base of the bank. Others found there whose death was 
not accounted for, were Harpalus dichrous Dejean (E. 
A. Schwarz), Tachysphex terminatus, Trypoaylon sp., 
Pseudagenia mellipes, Halictus pectinatus, Anthophora, 
and Xylocopa virginica. Thousands of dead Chalcid 
parasites were found in the burrows when they were 
examined during the winter. 
One often found newly dead female bees at the foot 
of the bank. This was very puzzling, until one day I 
actually saw where lay the trouble. A returning female 
A. abrupta found that during her absence another bee 
of the same species had appropriated her nest. A fight 
ensued, in which the usurper was thrown bodily to the 
ground and after a few twitches of the legs was dead. 
Other fights of a less serious nature were often observed. 
On one occasion I saw a female with part of her body 
protruding from the burrow. I pulled her out with the 
forceps, and found her tenaciously clinging with her 
jaws to a second female that had evidently intruded in 
the burrow. The next day also I saw the yellow, pollen- 
laden legs protruding from a bee which seemed to be in 
agony. I pulled it out with the forceps, and it, too, pug- 
