JAN. 1907. 
PEOCEEDINGS. 
5 
certain of them eluded the sand-wasps belong-ing- to the g-enus Bemhex. 
Mr. Brues remarked that Winthemia Jt-pustiilata was an unusually weak 
and soft-bodied Tachinid. JNIr. Colles asked if it were always the case 
that parasites were never reg ularly captured or destroyed by their hosts. 
This occasioned some discussion. The general opinion was that Tach- 
inids and other parasites as well were never, or at least very rarely 
captured by the host species, no matter how annoying they might be, 
or how many attempts were made. Mr. Brues suggested that this was 
a necessary provision for the perpetuation of the parasitic species and 
that it must be very strongly accentuated by natural selection. 
Dr. Graenicher next described a peculiar variation of instinct in a 
species of Crabro that he had observed several years ago late in the 
season. The female in question had built several nests, one on top of 
another in a hollow stem without laying any eggs in any of the cells. 
He also spoke of certain experiments by the French naturalist Fabre 
who had succeeded in getting certain bees to build nests in glass tubes 
in his study. He suggested that this would be an interesting waj^ to 
study the habits of Dr. Barth's Crabros, if they could be induced to 
nest under such conditions. 
Mr. Ward then asked if as a general rule the time required for the 
eggs to hatch, when incubated by the parent birds and in artificial 
incubators, was the same. ]Messrs. Barth, Graenicher, Colles, Russell 
and Brues joined in the discussion which followed. The general agree- 
ment was that only slight differences in the incubation period were 
produced by variable temperature. 
The meeting then adjourned, 
Milwaukee, December 20, 1906. 
Regular monthly meeting of the Society. 
President Teller in the chair and about 60 persons present. 
The minutes of the last monthly meeting were read and approved. 
Professor C. O. Whitman, of the University of Chicago, gave the 
lecture of the evening on "The Evolution of Species," the text of which 
appears on the later pages of the Bulletin. 
After the lecture President Teller thanked Professor Whitman in 
behalf of the Society for his kindness in presenting his interesting 
talk. 
The meeting then adjourned. 
The following papers were ordered printed by the board of 
directors : 
