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. californica, 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 WERE 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 off 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? 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- 
10 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. 
