The Ecology of a Sheltered Clay Bank 175 
following year if all these mothers, over 1000, had been 
left alive to propagate the proportionate population. 
It seems hardly possible that the clay bank could have 
held them (and we know that crowded housing condi- 
tions lead to ill health and ill morals). Would they, 
under such pressure, have disseminated over other areas? 
At the end of the season the results of this catastrophe 
could be seen, for on June 24, 1921, we could count only 
175 nests, as compared with the 675 counted for June 13, 
1920. 
The white-banded bee was now present, but in shame- 
fully reduced numbers. One can hardly say that the A. 
abrupta in ever increasing numbers had simply crowded 
out the white-banded bees, because there was so much 
unusued space about the clay bank, and the two species 
occurred at different times, so they could not have been 
in competition for the same flowers. It was almost wholly 
a question of parasites, and this is treated elsewhere. 
Other details on the life history of this bee, and the re- 
lation of the species to moisture, light, etc., are given in 
later pages.* 
White-banded Mining-bee, Entechina taurea Say [J. 
C. Crawford].** 
The preceding pages show how the mining-bees, An- 
thophora abrupta, rose in five years from a colony of 
few individuals to a great and important population. 
We have also seen how J. abrupta emerges early 1n sum- 
mer, does its life-work in about thirty days and is done 
he: logical aspects of the life 
Wess or ths ee othe Oe camerien species of bees and 
i : however, 
will be treated biologically in other papers to follow. It is, 
often difficult to draw the line between the two aspects of the study. 
**Mr. Rohwer writes that this bee is now known as (Entechnia) 
Melitoma taurea Say. 
