46 Trans. Acad. Sci. of St. Louis. 



from early morning, 4 to 6 o 'clock, to the evening of the 

 same day, the couples usually severing some time between 

 5 and 9 o'clock. This length of time seems enormous 

 when we consider the brief period they have wherein to 

 live and reproduce. We wondered whether this pro- 

 longed period was of any increased value to the species ; 

 whether a longer period of copulation tended to insure 

 the fertility of all of the eggs, or whether a large num- 

 ber of ova required a longer period of mating to insure 

 the fertility of all. 



We also wanted to know just what per cent of the eggs 

 were fertile, and if there was a higher percentage of fer- 

 tility among the first eggs deposited than among the last. 



This led to the experiments with Cecropia eggs from 

 insects which mated from 3 to 48 hours. 13 In this study 

 we found that there is absolutely no relation between 

 the time spent in copulation and the fertility of the eggs ; 

 that those insects which remained in copulo for 3 to 15 

 hours deposited eggs showing just as high a per cent of 

 fertility as those which continued for 18 to 48 hours. We 

 also found that those insects which carried an abnormally 

 large number of eggs had just as large a per cent of fer- 

 tility as did those with smaller numbers. In the former 

 work we found 77% of all the eggs were fertile and 23% 

 infertile. 



In 1913 similar work was carried on with 132 females 

 of the following 8 lots of Saturniids : 



22 $ 's Samia cecropia, River des Peres, St. Louis, normal 1913 



14 $ 's Samia cecropia, River des Peres, St. L., fluffy cocoons 1913 



11 $ 's Samia cecropia, South St. Louis 1913 



16 $ 's Samia cecropia, New York 1913 



27 $ 's Philosamia cynthia, Philadalphia 1913 



30 9 's Philosamia cynthia, New York 1913 



10 5 's Telea polyphemus, Fall River (2 9 's) 1913 



Telea polyphemus, St. Louis (1$) 1912 



Telea polyphemus, New York (1$) 1912 



Telea polyphemus, Augusta, Ga. (6 $ 's) 1913 



2 9 's Samia californica, California 1912 



13 The details of this work were published in Biol. Bull., 24: 245- 

 250, 1913. 





