Bau — Longevity in Saturniid Moths. 23 



in the males, the mated individuals survived longer and 

 in the females the unmated ones. And again in compar- 

 ing all males with all females we find the greater mean 

 longevity in favor of the males. 



The mean for the entire population is 10.24 days. This 

 is greater than that of any other lot of Cecropias of this 

 year excepting those from fluffy cocoons. Of course the 

 length of life does not equal that of the lot in 1910 which 

 emerged early and lived so much longer than usual on 

 account of the peculiar weather conditions. It is very 

 interesting to note that the mean longevity for this en- 

 tire lot is much higher than that of the same species 

 from the same locality only two years before (loc. cit., 

 p. 193) . Inspection of these tables will show that in every 

 case the mean duration was greater for the 1913 New 

 York Cecropias by from 2 to 3 days. 



From the Fall River lot of Cecropia cocoons only 9 

 moths were obtained. This material is insufficient to 

 warrant comparisons. (See Table 14.) 



DISCUSSION OF LONGEVITY. 



To briefly summarize all of the Cecropia data in a 

 comparative way, we should bring together the details 

 of Table 1 of this paper with Table 1 of the former pub- 

 lication. 



First we see that none of the Cecropia excepting the 

 1910 lot split up into distinct groups of early and late 

 emerging, and long- and short-lived individuals. The 

 reason why this phenomenon should stand alone and un- 

 repeated in the subsequent collections was the unique 

 weather conditions of that year, giving the extremely 

 favorable climatic conditions in March, hastening their 

 development to an early emergence, followed by an un- 

 usually cold April which caused them to live longer. But 

 when we compare the means for the whole population of 

 Cecropia moths in the various lots (see last column of 



