Rau — Longevity in Saturniid Moths. 17 



inviting to activity, and in due time expended their quota 

 of stored nourishment and died after the normal length 

 of life. Further experiments, keeping adult moths in an 

 ice-box, proved that cold markedly lengthens their life. 



We have then already stated that the mean duration 

 of life of the Cecropia moth was shorter in 1911 than in 

 1910 ; this may be correlated with the fact that the period 

 in which they lived was warmer in 1911. A comparison 

 of Table 8 with Table 1 (loc. cit., pp. 192 and 183), shows 

 that in every case a variation in the length of life accords 

 with a simultaneous variation in temperature. 



Now we come to the data of the 1913 Cecropia work. 

 The St. Louis Cecropias known as the River des Peres 

 lot were gathered from the same area, near Forest Park, 

 as in previous years. This time they were sorted into 

 two lots, one containing all of the normal cocoons, and 

 the other the loosely woven or fluffy cocoons. 5 336 in- 

 sects emerged from the normal cocoons between May 9 

 and June 16, 220 of which were used for longevity data. 

 (See Table 10.) 



Here again the mean duration of life was greater for 

 the mated males than the unmated males and vice versa 

 for the females. To be sure the mean length of life is 

 almost equal for the two classes, "all mated" and "all 

 unmated" insects, and also the groups "all males" and 

 "all females," but this equality is probably of little sig- 

 nificance since it results merely from the counterbalanc- 

 ing of the more significant numbers just referred to. The 

 mean length of life for this whole population was 9.86 

 days. 



Of the 79 insects which emerged from the fluffy cocoons 

 between May 5 and June 12, 74 were used for longevity 

 notes. (See Table 11.) 



s These were sorted out and treated separately for the purpose of 

 continuing the study (see Psyche, 18: 168-170, 1911) of this fluffy con- 

 dition to ascertain whether it is hereditary, and whether other differ- 

 ences, such as longevity, oviposition, etc., make them distinctly differ- 

 ent from normal cocooned insects. 



