The Ecology of a Sheltered Clay Bank 243 
harvested for study), or that portion which got the max- 
imum amount of sunlight. This is in striking contrast 
to Fig. 3, the southern half, which enjoyed only a lit- 
tle filtered sunlight. One can readily see that the de- 
gree of illumination made a great difference in choice of 
site by the A. abrupta. The white-banded bees, En- 
techma taurea, the caterpillar-wasps, Ancistrocerus ful- 
vipes, and the Trypoxylon wasps did not give evidence 
of so direct a dependence upon this factor. I have often 
wondered just what is the correct explanation of this 
correlation of warmth to longevity. I have discovered 
in other studies that in organisms that take no food as 
adults (Saturniid moths) increased warmth tends to 
accelerate the activity and thus exhaust the vital energy 
so that the life of the organism is cut to a much shorter 
duration than it would have been at a lower temperature 
where activity is retarded. So shall we say that be- 
cause A. abrupta chooses the warmest place in the sun, 
her activity is intensified and her life soon spent? Or, 
on the contrary, shall we say that her habit of choosing 
the sunny situations is a fortunate adaptation in that it 
enables her to get through with the necessary duties of 
life in the short period of time allotted to her, and that 
probably only those individuals which do exercise this 
choice will be able to finish their life-work and leave 
progeny? It should be noted that all the other insects 
mentioned in this study have a much longer time for 
their duties than A. abrupta, since they either lived the 
entire season, or had more than one generation each 
season. 
In 1917, the white-banded bees greatly outnumbered 
the Anthophora. While a few of the nests of the former 
were in the face of the bank, and often took a somewhat 
