4 BULLETIN 295, U. S. DEPAETMEXT OF AGRICULTURE. 
were found empty pupa cases/" or "Empty chrysalids were found in 
the pitch masses." 
Since no other pitch moth so seriously destructive to the trunks 
of mature or nearly mature trees leaves the entire pupa shell 
within the bark or the pitch which sheltered the immature insect, 
its identity is quite easily determined. 
The eggs deposited in July appear to hatch within about two weeks. 
During the latter part of August the young larva manifests its presence 
in infested trees rather plainly by the mixture of coarse castings and 
brown bark dust which is thrown out through the entrance and other 
holes in the bark made by the larva. Unlike the larva? of the sesiid 
pitch moths, the pine moth caterpillar does not work into the cam- 
bium and stay there. Quite often, if not always, after attaining 
nearly half its full growth, it leaves the place where it hatched and 
drills into the tree tissues again at a spot which presumably suits it 
better, not infrequently several feet away from the original spot. 
To this migratory habit probably must be attributed the frequent 
occurrence of but one larva in a wound, except in instances where the 
work of woodpeckers accounts for then isolation. This assumption 
seems to be supported by the fact that all such hermits when located 
are developed well toward maturity. 
As the larva grows and the inactive season approaches, this pro- 
miscuous gnawing of holes in the bark ceases. In no case even 
where most of them remain where they first saw the light is migra- 
tion resumed the following spring. In the spring each larva prepares 
for pupation in its own individual tunnel, though under the same 
space of infestation, by lining it with silky thread. Packard states * 
that "the worm in July spins a whitish, thin, papery cocoon in the 
mass of exuding pitch, which seems to act as a protection to both the 
larva and the chrysalis." This applies to the insect in the East. 
In the West the caterpillar of the pine pest restricts its weaving 
operations before pupating to the above-mentioned lining of the 
tunnel. Cocoons which answer Packard's description are frequently 
found in these tunnels, but they are of a parasite which will be 
referred to later. 
On approaching maturity, about the middle of June, the larva 
grows sluggish and is found to be transformed into the chrysalis 
within a few hours. When the moth has attained full development, 
29 days from the time the pupa was formed and a year after the egg 
was laid, it merely bursts the chrysalid skin, leaving the empty shell 
within the tunnel, and pushes its way out through the very thin 
pitch covering at the mouth of the tunnel. The period of pupation 
in captivity under very varying temperatures and during all seasons 
i Packard. A. S.. Insects Injurious to Forest and Shade Trees. 5th Rpt. U. S. Ent. Com., 955 p. (p. 
731), 38 pi., 30b fig., 1S86-1890. 
