1912] Life History of Trogoderma Tarsale Byes 
growth of the larva depends to a considerable extent on temper- 
ature and the abundance of food, and it is retarded by cold 
weather and scarcity of nourishment. 
The foregoing factors, however, are not always the cause of 
slow development. I have noticed that in almost every brood 
there is a wide variation in the growth of the various specimens 
under identical external conditions. Very often some speci- 
mens attain full size, metamorphose, and produce young long 
before others are half grown; but not infrequently do these 
young overtake the other members of their parent group and 
even reach maturity much sooner under the same conditions. 
The small, oblong, white eggs are apparently all of the same 
size and yet some of the larve hatching from them seem to be 
unable to get started in their development. The majority of 
the specimens, however, mature in about the same length of 
time, which is from five to six months. 
Another very interesting thing which occurred regularly in 
these studies is the fact that frequently some individuals attain 
an apparently full size within a comparatively short time, but 
do not enter the pupal stage for a surprisingly long period 
thereafter. These larve are active, continue to feed, and are 
‘normal in their behavior, but there must somewhere be a cause 
for the sudden halt in their development. We are keeping in 
the laboratory a large number of larve which have been full- 
grown for over two years, and even very favorable conditions 
do not seem to effect a metamorphosis. A number of speci- 
mens are being kept under different conditions, but thus 
far nothing entirely conclusive has been obtained. 
Summary of Variations in the Life History of Different 
Individuals of the Same Generation. 
1. The adults lay eggs from three to seven days after 
emergence. — 
2. The number of eggs laid by different individuals varies 
from five to sixty-two in number. 
3. The eggs hatch in ten to sixteen days, depending largely 
on temperature. 
4. Larval life lasts from five to forty months or more.* 
5. The time of pupation is from eleven to seventeen days. 
6. The age of adults varies from ten to thirty-two days. 
*At present we have a number of live larve which have lived forty months. 
