42 College of Forestry. 
first at about the fourth day, the second on the seventh day, 
the third on the ninth day, the fourth on the twelfth day 
and the fifth (pupation) on the eighteenth day. It is an 
interesting fact, attested to both by a study of the contents 
of the burrow and by measurements of larvae taken when 
actively engaged in burrowing, that nearly half of the length 
of the burrow is made during the last. larval stage. 
Tue Pupat Sracr.— About a day before pupation the 
full-grown larva completes the pupation chamber and ap- 
parently ceases to feed hereafter. The position of the pupa- 
tion chamber depends considerably on conditions of tempera- 
ture and of moisture. It has already been said that larvae 
pupating in the late fall build their pupal chambers deep in 
the sapwood. Exactly the same is true at any season of the 
year if moisture is lacking. If conditions of temperature 
and moisture are favorable, however, the pupal chamber may 
be constructed half in the sapwood and half in the bark, or 
even nearly entirely in the bark if this is also quite thick. 
The period of pupation was best observed in burrows ex- 
tending rather deep into the sapwood so that only a small 
‘“‘ window ” was opened on stripping back the bark. A num- 
ber of such burrows were exposed April 26th and found to 
contain full grown larvae, snowy white in color — the in- 
testinal contents having all been expelled — which were ap- 
parently just ready to pupate. These were examined from 
time to time during the day, the strip of bark being replaced 
after each time and the larvae being prevented from drying 
by moistening the bark. They did not pupate during the 
day, but the following morning, April 27th, at 8.30 a. m., 
the pupal stage was fully established. The white trans- 
parent pupa was still quite soft, hardly capable of movement. 
On April 30th the color of the developing adult within was 
beginning to show through. The mandibles were brown and 
the rest of the body cream color. It was quite active, con- 
tinually rotating in its burrow by movements of its abdomen. 
On May ist the specimen was still more active and the color 
was still darker. The mandibles were dark brown, nearly 
black in color and the rest of the body a decided tan. The 
