186 PHIL RAU AND NELLIE RAU 
early emergence followed the exceptionally warm month of March 
at once leads one to suspect that the high temperature at that 
stage of their pupal development may have accelerated growth. 
The mean temperature for March, 1910, was 57.5° F., as contrasted 
with 44° and 47° for the other two years, andthe maximum reached 
was 87°.18 
It was noticed that during some of the cold days of April and 
May the animals showed signs of extreme sluggishness, and while 
Cecropias in confinement seem to be inactive only during the day, 
those which were on hand when the cold snap came were extremely 
sluggish during both day and night. It was thought that the 
cold had a direct effect upon the duration of life, for when the 
animals were inactive, little or no reserve nutriment was consumed 
and this saving of vital energy, which is never replenished, may 
have prolonged their lives. A correlation clearly exists between 
temperature and longevity. We find that almost all of the long- 
lived insects (table 2) emerged between April 13 and May 10. 
These died at intervals between April 27 and May 29. The aver- 
age of the daily mean temperatures for this period of 47 days was 
57.5° F. The short-lived ones emerged between May 11 and 
June 17, and died between May 21 and June 28; the average 
of the daily mean temperature for this period of 49 days was 
68.1° F. Therefore the average of the mean temperature was 
lower by 11° during the time when the long-lived insects existed. 
Now when we tabulate these two groups separately (tables 
3 and 4), we find the mean duration of life of the early lot to be 
16.65 days, while that of the late ones which ran intowarm weather, 
is only 10.14 days. 
13 To quote from the Monthly Meteorological Summary of the United States 
Weather Bureau: ‘‘The weather for March was very unusual. The mean tem- 
perature was 57.5° which is 3.2° higher than for any previous March and the tem- 
perature was continuously above the normal except on the 9th, 10th, 14th and 
15th. The maximum temperature for the month was 87° and this has been 
exceeded but once in March in the history of the station. Freezing temperatures 
occurred on three days only. . . . . The number of clear days, 22, is the 
highest ever observed in March, and the number of cloudy days, 2, the lowest. 
The sunshine was 79 per cent of the possible amount and was greatest for March 
since the records began. 
All temperatures given in this paper are quoted from these reports. 
