The Nuptial Flight 131 
stick doggedly to their usual program, excepting under unusual 
counter stimulation. But more than this is evident from this 
experiment. The first moths were liberated a half-hour before 
the second lot, yet they did not come in from the yard a minute 
Sooner, but simultaneously with the latter. Now the dawn was 
just beginning to break at 3:20, and during the next ten min- 
utes, the first 7 of these moths of both lots came in. May it be 
that, while the emanations of the females are the primary 
inducement to arouse the males to activity, yet a secondary 
stimulus may exist in light of a certain intensity, or meteorolog- 
ieal conditions, or some such factor, to which also they are 
delicately attuned and to which they respond? In later experi- 
ments, recorded in the following pages, wherein tests were made 
within doors where conditions could be watched all the time, 
these moths showed, night after night, a periodic activity before 
nine o’clock, which brought all of the males to the window. 
This window, facing the street, admitted a subdued light from 
the street lamps, park lights and passing automobile lights. The 
full light of day streaming through this window did not elicit 
any response from the moths, but after a period of rest during 
the daytime and after nightfall, at about 8 o’clock, they pres- 
ently flocked to the window. My opinion is that this mellow 
light from the various sources was very nearly akin to the light 
at break of dawn, and the moths react to both in the same way. 
Exp. 32. June 27. Wind, southeast; station, 50 feet north- 
west. Previous experiments show that the male cynthias fly 
to the cages of their mates when the moon shines brightly. This 
test was now repeated, with the same wind and distance, 50 ft., 
on a dark night. 52 males were liberated in the back yard at 
10:20 p.m. The moon was completely darkened by clouds. I 
harvested the returning moths until midnight, and since, by 
that time, I had sufficient data to show that he lack of moon- 
light is no deterrent to their activity, I went to bed. They 
began to come in a few minutes after their liberation, and up 
until midnight, 17 had arrived. 
Summary. 
Although tabulation loses much of the evidence yielded by the 
individual experiments, such a summary gives one a grasp 0 
Some aspects of the work as a whole. 
