38 College of Forestry. 
On the following morning, March 31st, just seven days 
from the time of laying, the eggs observed the preceding day, 
were found with the outer end open and the larvae were 
busily engaged with their mandibles on the egg membranes, 
their heads being partly free but their bodies still in the ege. 
With one exception the bodies were still white and trans- 
parent. This one specimen was entirely free of its membrane 
and had carried its burrow nearly half the length of its own 
body into the bark and the contents of its digestive tract 
showed brown through the body wall. The incubation period 
seems to vary little or any in the same burrow. ‘The eggs 
nearest the nuptial chamber which are laid first nearly in- 
variably hatch first, and the burrows of the larvae arising 
from them are correspondingly longer. This condition is 
very clearly shown by Fig. 26. 
Tur Larva.— The larva immediately after hatching is 
from .518 to .580 mm. long by .30 to .382 mm. broad at the 
broadest place which is through the head. It is a footless 
erub, sub-eylindrical in shape, transversely wrinkled. It 
is at first pure transparent whitish in color except the head 
which in the region of the mouth, is a light yellowish tan 
shading off to white at the back of the head and to a dis- 
tinct brown on the mandibles. The larva is widest at the 
anterior part, the head being a trifle wider than through 
the thorax at this stage. The abdomen tapers at first gradu- 
ally, but more abruptly toward the posterior end, which is 
reflexed ventrally. 
Later, after the larvae has fed for some time, the general 
proportions of the body change considerably, the head re- 
maining the same size for several days, while the thorax and 
abdomen increase in all three dimensions. By the time the 
larval burrow is one mm. in length, the thorax is usually as 
wide or evenly slightly wider Toa the head, and it so con- 
tinues to be throughout larval life. At the completion of 
each moult the head increases in size at once and then re- 
mains without growth until the next moult. The covering 
of the body on the contrary seems to remain much softer and 
growth appears to be more of a continuous process. The 
