266 Wisconsin Academy of Sciences, Arts , and Letters. 
represented in the long and in the short periods. A second table 
was made, using the life histories in table 1 and material from a 
number of incomplete records, to show the length of stadia in 
days, and from it were plotted curves showing the variation in 
stadia. It will be noticed that in the average life the first stadium 
is nearly four days long. From this the stadia gradually decrease 
in length until the sixth is reached. Then an increase in sta¬ 
dium duration begins and goes rapidly on until the last stadium, 
which is always much the longest of any, because of the time 
taken for cocoon spinning. The moths emerge in about seven days 
from the date of pupation. 
in 
R 
c> 
4 —> 
I .2 3 + 5 6 7 8 ? 
Ttu^nteT Of Ecdyses 
Fig. 1. Curves showing variations in stadia of larval life. 
_ Curve of larval life with eight ecdyses. 
. Curve of larval life with nine ecdyses. 
- Curve giving combination of both. 
