Rau—Longevity in Saturntid Moths. 75 
been too often committed of placing generalization be- 
fore accurate and adequate investigation. It will be 
quite fitting, however, to take the few conclusive results 
gleaned from this detailed study and construct from 
them and around them a scheme which would sys- 
tematize these factors in their relation to the propaga- 
tion of this small group. 
The very beginning of the adult life shows the simple 
adaptation to environment which is common to a large 
proportion of the members of the animal kingdom; their 
emergence is accelerated by high temperature early in 
the season or retarded by late cold. While this would 
be of advantage only to those species which are inter- 
ested in vegetation, it is interesting to find the condition 
existing in these animals also which can have no con- 
cern for food, excepting for a food-plant upon which to 
deposit their eggs. In other words, they come out at 
warm periods, soon to wear themselves out, while they 
might live much longer if they came out during the colder 
days, since, as our experiments have shown, cool weather 
greatly prolongs a quiet life. 
In practically all of this material we find the males 
emerging before the females. This may or may not be 
due to the fact that the females have the ova to produce; 
nevertheless, the males are on hand for the function of 
fertilization when the females appear, and hence this 
delicate adjustment of life, whatever its rise, is an ad- 
vantage to the species, while it is of no help that we can 
now see to the individual. 
The homologous length of life of the sexes harmonizes 
well with the monogamous habit which a large part, at 
least, of these insects follow. We must acknowledge that 
it is well for the species that the females are permitted 
as long a life as they have, in order that they may com- 
plete their long task of egg-laying. The males on the 
other hand have a comparatively long, useless period of 
life after mating. Since polygamy is known to exist in 
other species of this family, and in some here dealt with, 
