164 Trans. Acad. Sci. of St. Louis 
portance in an understanding of the quest of the male. If 
the odor were light and volatile, and diffused in all directions 
equally, like ripples on a pond, there would be little chance 
for the male to locate the source. The course followed by the 
moths in approaching the roof where the females are gives 
slight indication of the nature of these emanations. Sometimes 
the males would approach from a distance flying near to the 
ground and only when near to the house would they turn their 
course upward and over the edge of the roof; at other times 
they could be seen for some distance flying at the level of the 
second-story roof, 
At one time the only females that we had out on the roof 
were those which had hatched from the New York cocoons, yet 
for several days the native Missouri males flew to them in great 
numbers; this would indicate at least that the odor was not 
noticeably different in the moths. from two widely separated lo 
calities. Of course, one would only expect that geography would 
make no difference in the odor glands of the moths, but so many 
queer things happen in nature, and so many unexpected factors 
have come to light in the details of the present problem, that I am 
glad of the opportunity to know positively that Nature sub- 
stantiates our expectation in this matter. 
When many cages containing female cecropias were on the 
roof and there was more choice for the males, they spent much 
more time fluttering and hesitating before alighting. Early in 
the work when there were only three cages of females at the 
window, the flight of the males was very direct, but when the 
odors emanated from a dozen cages scattered over the roof, the 
males had difficulty in choosing the desirable cage. Quite often 
they would spend from two to five minutes fluttering about the 
roof, apparently in confusion. In several instances the males 
were seen to fly in a straight line past the roof and a few feet 
beyond; then, apparently discovering that they had gone too 
far or at least lost the trail, they turned squarely around and re- 
traced their wingsteps to the right place. ae 
There were on the roof at one time three cages contaiming 
polyphemus females, but not one of the cecropia males ever made 
the mistake of even alighting on one of these. Likewise, z 
though polyphemus males came to the roof oceasionally, they 
did not rest on the cages of the other species. The relationship 
>» 
