Séance du 16 Avril 192A 
109 
i2. The longevity of the females of the second 
generation. 
This ord'er may at first seem somewhat peculiar, 
but the reason for it will appear as the various points 
are studied. 
1. The Longevity of the Female. 
Of the 123 individuals which reached the last 
stage, 63 were females. Of these, 7 died in moulting 
or were so badly damaged that we destroyed them, 
• 
1 5 had made no egg-case by the end of November and 
were set free after four or five months of captivity in 
the adult stage, and one died after i 3 o days without 
having made an egg-case. This leaves us with 4o fe¬ 
males, of which 5 were placed in cages with males 
shortlv after the last moult and 2 after thev had al- 
t j *,• 
ready made a certain number of egg-cases. Copulation 
was observed in every case and in some several 
times. The 33 totally unfertilized females remaining 
made one or more egg-cases and were kept until they 
died. 
The factors which determine the length of the 
life of an insect are complex, and their separate ef 
fects cannot be distinguished easily, as the most im¬ 
portant of them, the vitality of the individual, affects 
them all. We need not consider here death by vio¬ 
lence, which is of so much importance in the open, 
and we have eliminated the cases due to obvious ac¬ 
cidents. 
< * 
The food supply was always ample in the cases 
