Ban — Longevity in Saturniid Moths. 73 



THE DURATION OP THE PERIOD OP COPULATION OF TROPAEA 



LUNA. 



Notes were made on the time spent in copulo by four 

 pairs of T. luna. One pair remained in copulo 5y 2 

 hours, two pairs for 6y 2 hours, and one pair for 9 hours. 



COCOON SPINNING. 



The following was the only note that could be made 

 on the spinning of 8. cecropia : 



June 15, at 4 p. m., the cocoon was being commenced ; 

 just a few silken threads were spread over the insect. 

 At 6 o'clock the next morning the cocoon covered the 

 entire insect, but was so thin that the green caterpillar 

 could be seen through it. By 4 p. m. the thickness had 

 increased to such an extent that the insect could no 

 longer be seen. So with a sharp knife a slice was cut 

 off the side of the cocoon, making an opening about 

 y 2 by 1/4 inch. Two hours later this was spun over; 

 hence, the work was evidently still in progress on the 

 inside of the cocoon. 



SUMMARY. 



1. We find that mating does not significantly 

 lengthen or shorten the life of the males in any of the 

 material observed. 



2. In all of the groups studied the unmated females 

 lived longer than the mated females. 



3. In Polyphemus as a whole we find the females 

 much longer lived than the males, and for the entire 

 population the mean is much greater for the two south- 

 ern localities, St. Louis and Augusta, than for the two 

 northern regions, New York and Fall Eiver. 



4. In the Prometheas the mean length of life for 

 the whole 1913 Fall Eiver population is much longer 

 than in the 1911 Creve Coeur lot. Just the reverse ex- 

 ists in the Polyphemus from the two regions. 



