Ran — Longevity in Saturniid Moths. 61 



to 15 hours, gave a total of 817 eggs, 12% of which were 

 infertile. 



SAMIA CALIFORNICA. 



For the Samia calif ornica we have notes on only 2 in- 

 sects. (See Table 34.) 



The first mated 28 hours and yielded 20% of infertile 

 eggs, while the second, after only a 13-hour mating had 

 barely 1% of infertile eggs. 



THE MINIMUM DURATION OF MATING IN RELATION TO 



FERTILITY. 



In our four Cecropia tables already presented are 6 

 females which mated only 2 hours, yet had a perfectly 

 normal proportion of fertile eggs, while the seventh was 

 entirely infertile. We were eager to find just what the 

 minimum duration of copulation could be to insure the 

 fertility of a normal amount of eggs. 



The period of mating of 3 females was limited to 1 

 hour, and of 1 female, to 2 hours ; from all these, not one 

 egg was fertile. 



Hence the minimum duration of mating required for 

 complete fertilization of the egg mass must be between 



1 and 2 hours. Of course the one insect which mated for 



2 hours and yet gave no evidence of fertilization may 

 have been sterile, since we have data on a number of 

 2-hour matings, recorded elsewhere, a large proportion 

 of which proved quite fertile. 



Period of Incubation, 

 samia cecropia. 



In a previous series of observations on the period of 

 incubation of Crecopia eggs, 16 we found the period of 

 incubation for the eggs deposited each day by each female 

 to vary from 6 to 11 days. The length of time for the 

 great majority was 8 or 9 days. All but two of the 36 



is Psyche. 19: 69, 1912. 



