149 
quently necessitate additional food), to devour their excrement once 
or twice or even a third time. On the other hand, among grain 
kept in the laboratory during the winter, in a favorable temperature 
the greater part of the time, I have found kernels containing from 
one-fourth to one-third of the substance untouched, together with 
the empty chrysalis, showing that the worm had passed through its 
entire transformations and yet had food to spare. 
After attaining its full growth, the larva withdraws to one side of 
the grain, cuts out a disc to provide for the escape of the moth, 
spins its cocoon, and either passes the cold season in a torpid state, 
or transforms to the chrysalis at once, as the case may be. 
The larve from eggs deposited by the second brood of moths at- 
tain their full growth, or nearly so, before the first cold weather in 
the fall, and pass the winter in this stage, eather within the cocoon 
or before it has been constructed. 
But they may winter in almost any stage of their growth, as a 
low temperature only causes them to pass into a dormant state, to 
awake and resume work when it rises above 60° Fah. At this tem- 
perature, they mature in about three weeks. When the larva changes 
to the chrysalis, its head is at the circular disc which it has prv- 
viously cut; the anterior extremity of the chrysalis is also in the 
same position, and by the aid of the setw mentioned in the de- 
scription, it pushes against this disc, and finally presses it out and 
makes its escape, leaving the empty shell within. 
The presence of the insect, either as latva or chrysalis, in the 
grain is not easily detected, the kernels looking as plump and of as 
good color as though they were sound; but in weight their difference 
is instantly and strikingly apparent. T found, for instance, that, on 
an average, 895 grains of wheat will weigh one ounce, while it re- 
quired 1,085 grains of infested wheat, from the same stack, to weigh 
as much,—and this too before the larve had finished their work. 
A ready method of determining the presence of the pest in grain is, 
to place a quantity in water, when the infested grains and those 
which have been eaten will generally float on the surface. 
SUMMARY OF THE LIFE HISTORY. 
The insect passes the winter in the larva state, pupates in the 
spring, and the moths appear in May or June. These pair imme- 
diately, and deposit their eggs on the young grains of the new crop 
in the field, if they are allowed to escape, or, if not, on the grain 
in the bins where they originated. These eggs hatch in from four 
to seven days, and the larve burrow into the erain and themselves 
transform to moths, about August, or often during the latter part 
of July. These moths pair and deposit their eggs after the manner 
of the previous brood, and the larve from these, nearly, if not 
quite all, reach maturity during the fall and transform the fol- 
lowing spring. The number of broods and time of appearance vary 
ereatly, with the climate and season, in warm countries broods fol- 
low each other in rapid succession during the entire year. 
—10 
