The Ecology of a Sheltered Clay Bank 229 
the rose bushes, seemed especially attractive to a large 
variety of insects. Flies and parasitic Hymenoptera 
were particularly abundant in variety, but for large 
numbers of a single species only two were notable; they 
were Chalybion caerulewm males, discussed elsewhere 
in these pages, and males of this species. There was 
another similar shrub near by, but no such insect popu- 
lation was apparent upon it, so I concluded that it was 
the aphids present here which had attracted them to 
this one, although I could see no actual relationship ex- 
pressed in their activities. Perhaps in both species, 
the males were merely marking time until the appear- 
ance of the females. It is interesting to note, how- 
ever, that while the males were so near to the clay bank 
on this occasion, they probably flew here from else- 
where, for the females of this parasite have never been 
seen at the bank. 
Sapyga sp. [S. A. Rohwer]. One was walking about 
on the bank on June 29, 1917. Members of this family 
are, according to Rohwer (Conn. Nat. Hist. Survey 
22:620. 1916), parasitic on bees and wasps, while 
Packard (Guide to Study of Insects, p. 134. 1876) says 
that in Southern Europe Sapyga repanda is parasitic 
in the nests of Xylocopa violacea; Sharp, however, (In- 
sects, Pt. 2, p. 100) says that Sapyga 5— punctata was 
seen carrying caterpillars. : 
Sphecodes sp. Two specimens of this red-bellied 
parasitic bee were seen going in and out of the burrows 
of the resident bees on June 28, 1920. 
Diptera. 
Of all the Diptera taken at the bank, not one speci- 
men was other than parasitic; the group as a whole may 
