The Ecology of a Sheltered Clay Bank 233 
tigrina were seen repeatedly to fly violently against the 
wood beside the Xylocopa or other burrows; then often 
I could see the tip of the abdomen enlarge, as it was 
bent downward and tightly pressed against the rough 
surface, and moved in a circular motion as it rubbed 
against the wood. In only one instance did I actually 
See something fall, but I was not near enough to see 
whether it was an egg or excrement. So the problem 
of the life history of this parasite remains unsolved. 
It would at first appear that A. tigrina came too late 
in the season to affect the bees, Anthophora abrupta, 
since their lives had terminated before the advent of 
the parasites. This might be true, and A. tigrina might 
not affect this species but might be a direct cause of 
the gradual lessening of the numbers of the white- 
banded bees, Entechnia taurea, which were contempo- 
raneous. However, if Fabre’s theory holds true for this 
species and these parasitic young possess those won- 
derful adaptations for reaching their host even through 
prison walls, then the parasites would affect the dormant 
generation of Anthophora, and other species as well. 
There is additional evidence, however, in the fact that 
I found the shedding-skins on the face of the bank, but 
not on the top, and A. abrupta builds only in the face of 
the bank. This would lead us to think that A. abrupta 
is a host despite the fact that the adults are not con- 
temporaneous. 
I want to repeat that in constant watching during 
these dipping maneuvers, I failed to see an egg drop, but 
from the insect’s behavior I felt sure that something was 
happening. It is reasonable to believe that the egg is 
minute, and with the observer four feet away (one can- 
