36 Trans. Acad. Sci. of St. Louis. 



Polyphemus. When all of the lots of Cecropias are taken 

 together, we find that copulation increases the percent- 

 age of oviposition by 12%. 



Our Luna moths showed a high percentage of oviposi- 

 tion, 95% for the mated moths and 89.5 and 86.2% for 

 the unmated St. Louis and Pike Co., respectively. 



Our data on S. calif ornica, although very insufficient, 

 shows precisely the same tendencies as in the other spe- 

 cies, the mated insects depositing 95% of their eggs, 

 while the unmated moths reached only 60%. The Pro- 

 metheas also give evidence of this tendency, but with a 

 lower percentage of oviposition. 



AGE WHEN FIRST EGGS WEEE DEPOSITED. 



We have elsewhere stated that mating is not the neces- 

 sary precedent of oviposition, although it has become 

 apparent in the preceding chapters that that function 

 exerts some influence upon egg-laying. So it is not un- 

 usual that we at first thought perhaps the unfertilized 

 females "held ofT egg-laying in the hope" of mating, and 

 that if mating did not occur before late in life the ovi- 

 positing then commenced without it. With this ques- 

 tion in mind we have compiled a table showing at what 

 age 142 unfertilized females began to oviposit. (See 

 Table 21.) 



It will be noted that in no instance did oviposition be- 

 gin after 7 days of age, nor on the first day 10 of the in- 

 sect's life. 29% of the moths commenced ovipositing 

 on the second day of their life, 40% on the third day, 

 19% on the fourth day and the remaining 12% of the in- 

 sects began at the age of 5, 6 or 7 days to oviposit. This 

 shows clearly that oviposition begins in due time, despite 

 the fact that such oviposition is of no use for the propa- 

 gation of the species, but that by conserving this ma- 



io The first day of an insect's life is the same day wherein it emerged, 

 but it may have emerged late in the day and hence its first day may 

 consist of only a few hours. 



