LIFE HISTORY AND HABITS. 31 
phytic. An attempt was made to rear some of the pupae in the plas- 
ter-of-Paris cages, but the cages seemed to be too damp, and all the 
pupae died. These appeared like those killed in the flooded cages, 
and the same bacterium and fungus infested them. 
VITALITY OF THE PUPA. 
The pupal stage is the most unprotected state in the life cycle of 
this insect, and is the one wherein the insect is most liable to mechan- 
ical injury. A small percentage of the pupae dug up out of doors 
were injured when their pupal cells were broken open, and conse- 
quently died. On the whole, however, the pupa is not nearly so 
susceptible to injury as is the popular belief. Such pupae as were 
unearthed in the field were kept under artificial conditions and 
handled quite roughly and often, yet most of them produced adults. 
The two pupae which were photographed for this bulletin (see PI. V) 
were handled several times with forceps, were exposed on a glass plate 
to light and temperature for hours, and on one occasion were dropped 
from the table to a chair, a distance of about 10 inches. In spite of 
this treatment both produced normal adults, and when last observed, 
October 14, 1912, were alive. There were several similar cases in 
which the results were the same as in the example cited. The pupae 
are quite helpless and are unable to make new pupal cells in case the 
old ones are destroyed. For this reason, probably, a large per- 
centage of those disturbed in the field die from exposure. The pupae 
are sensitive to light, heat, and contact, and when disturbed move 
their abdomens in such a way that the tip describes a circle. As 
the pupa becomes older it becomes more deeply colored and more 
sensitive and active. 
CHANGES IN COLOR OF THE PUPA. 
The first signs of coloration of the pupa are the eyes, and these 
appear as dusky bluish spots. The abdomen and thorax then be- 
come slightly yellow and the mouthparts and wing covers very 
faintly dusky. The tip of the abdomen remains whitish. About a 
week before emergence the entire pupa becomes darker, and just a 
few days before emergence the wing covers and mouthparts are 
quite dusky and the eyes assume a dusky color, the mouthparts, 
eyes, and wing covers remaining a little the darkest and being quite 
conspicuous. 
LENGTH OF THE PUPAL STAGE. 
The length of the pupal stage under laboratory conditions varied 
from 25 to 36 days, with most of the adults emerging in about 26 
to 32 days. These were kept as nearly as possible under conditions 
which would compare favorably with field conditions. This gives, 
roughly, a period of a month for the pupal state. 
