130 Trans. Acad. Sct. of St. Louis 
made two flights previously. It is interesting that of those 
which had made one flight 1 returned, while of those which 
had made two flights, all four returned. This juicy morsel of 
data tempts one to rumination, but we had better refrain in 
this case, for this is probably only a matter of chance in dealing 
with small numbers. These five did not come in among the 
earliest, but just along with the others, from 9:35 to 11:07. 
Thus 33 per cent of the youngest moths came in, 77 per cent of 
those 1 day old, and 62 per cent of the old fliers. In all, 28 
moths, or 64 per cent of the number liberated, returned; this is 
_ strikingly similar to the per cent (61) that returned from the 
front yard, the same distance in the windward direction. The 
chief difference lies in the fact that the latter were set free in 
the midst of their active period and still took a longer time to 
come in. 
Exp. 31-3144. June 25. In the previous experiment we have 
seen that when male cynthias are liberated early in the evening 
they become active at about 9 o’elock, and the activity lasts until 
about midnight. In the cecropias, the similar period of activity 
is from 3:30 to 4:30 a. m. Experiments have shown that when 
cecropias are liberated early in the evening, they do not fly to 
the females, but wait for dawn.* Conversely, one would infer 
that if one liberated cynthias after their normal period of activ- 
ity had ended, they would not fly to the females’ cages that 
night, but would hold off flight until the following night, so 
they could fare forth at their usual hour. To put this question 
to test, the following cynthias were liberated in the early morn- 
ing hours, after their normal period of activity had ended for 
that night: 6 males, 114 days old, which were liberated at 2:45, 
and 18 that had come in before midnight, after having made two 
previous flights, which were set free at 3:15, in the back yard 
in a favorable location. Of the 6 young males liberated at 2:45, 
3 returned, at 3:20, 3:24 and 3:27 a. m.; of the 18 experienced 
fliers, 11 returned between 3:22 and 4:15. This reveals at once 
that these moths do not postpone their flight until the next 
night, when liberated after their usual period of activity 1s 
past, but modify their habits and come in at some other time. 
In this they differ from the cecropias, who, for the most part, 
*With very few exceptions. 
