30 Trans. Acad. Sci. of St. Louis. 



period of their growth and spin these cocoons about 

 themselves. After a very brief period in the cocoons the 

 larvae transform into pupae. It is in this pupal stage 

 that the development of the eggs occurs. When a female 

 emerges as an adult, Nature has already prepared her 

 for her brief life by having all of the eggs matured and 

 ready for oviposition. In some of the longer-lived Lepi- 

 doptera, some of the eggs are being deposited while oth- 

 ers are maturing. Here, however, the eggs are all ready 

 to be laid when the insect emerges from the cocoon, and 

 when these are laid, or sometimes before all are depos- 

 ited, she dies. With conditions such as these it is easy 

 to tell precisely the total number of eggs carried by each 

 individual. 7 Of course, we assume that the total num- 

 ber of eggs carried by each female is influenced by the 

 home conditions of the larva, that is, food, climate and 

 moisture, and that the local conditions of the last few 

 months of pupal life, spent at St. Louis, could not in 

 any way influence the number of its eggs. 



During 1911-13 we made a study of the eggs carried 

 by the 504 individuals of 19 lots of these moths. (See 

 Table 19.) 



For convenience the numbers of eggs carried were 

 thrown into groups of twenty, but the averages in the last 

 column were reckoned from the actual numbers. The 

 table gives some interesting comparative details. For the 

 five lots of Polyphemus material the means vary from 

 198 to 293 eggs. The mean number of eggs carried by 

 the Fall River Polyphemus of 1913 equaled that of St. 

 Louis for the same year. The St. Louis lot for 1911 had 

 the largest average while the New York 1912 lot ranked 

 second, but for the last two the numbers of observations 

 were small, and one must be cautious not to lay too much 

 weight upon this evidence. The Polyphemus from Au- 

 gusta, Ga., had the smallest average number of eggs, 198. 



7 This is done by adding the number of ova deposited to the number 

 retained as revealed by dissection after death. 



