The Ecology of a Sheltered Clay Bank 187 
The caterpillar wasp, Ancistrocerus unifasciatus Sauss. 
[S. A. Rohwer]. 
Three mothers of this species were seen carrying 
green caterpillars into cracks of the old building above 
the clay bank, on May 28, 1921, where they were evi- 
dently nidifying in the old mud nests of Sceliphron cae- 
mentarium. I have previously recorded* the fact that 
they use the old cells of this mud-dauber. 
The spider-wasp, Episyron biguttatus Fab. [S. A. 
Rohwer]. 
This Pompilid wasp was seen kicking dirt into a small 
burrow at the base of the clay bank. She would quickly 
Sweep in the earth with her front legs and then with 
rapid beats of the tip of the abdomen she would pound 
it down. The wasp was taken and the burrow opened; 
one-half inch below the surface we found a perfectly 
round cell of the size of a pea, which contained a spider 
with an egg cemented to the dorsal side of the abdomen. 
The pipe-organ wasp, Trypoxylon politum Say.** 
This wasp should probably be included among the 
. inhabitants, since three large pipe-organ nests were 
Were built on boards or joists of the porch over the 
bank, but a more logical and interesting reason for 
including it was that several of these mothers were seen 
foraging for spiders which made their homes in the old 
bee burrows. Thus the species which seemed almost an 
outsider could affect the life of the community even 
though in a small way, by reducing the number of spider 
*Ent. News 24: 396, 1913. 
**Formerly called T. albitarse. 
