12 Trans. Acad. Sci. of St. Louis. 



contribute something toward determining the duration 

 of pupal life. 



In Polyphemus, the two southern localities yielded ma- 

 terial of longer life than the two northern ones. May not 

 this be considered a natural consequence of the animals 

 having favorable conditions of growth and abundant 

 supply of food in their developmental stages ? Or should 

 it be considered an indication that up north the tendency 

 is toward going through the life cycle and reproduction 

 in a lessened period? 



Comparing now the tabulated summaries of the data 

 on these four lots of Polyphemus from as many widely 

 remote localities, we find that in absolutely every case 

 the mean duration of life in the unmated females exceeds 

 that of the males by 1.34 to 2.89 days. We must realize, 

 of course, that every hour counts much in the life of one 

 of these frail creatures, and that even this brief time 

 represents approximately 20% of their normal lifetime. 

 We may well disregard the 9 mated individuals in the 

 Georgia lot, since their number is inadequate to be reli- 

 able for any conclusions. 



It does indeed set one a-searching for reasons and ex- 

 planations — to find that this condition of greater life of 

 the female should exist in every lot of this material, each 

 lot from a region far remote from the other, but this 

 condition or character must exist in Polyphemus ' nature, 

 and must be a specific part of them as much as any ana- 

 tomical character. We feel that these conclusions may 

 be considered reliable, since they are based upon the evi- 

 dence from so great a number of insects. 



In comparing the mean duration of life of the entire 

 population of these five lots, we find some divergence, in 

 fact, great divergence when we consider what time 

 means to these creatures. The St. Louis 1913 Polyphe- 

 mus were the longest lived, with the mean for the whole 

 population at 9.59 days. The Augusta material ranked 

 next with a mean duration at 9.03 days; the New York 



