DAMAGE TO WOOD OF FIRE-KILLED DOUGLAS FIR. 3 
(2) Certain species and classes of bark and wood boring grubs 
hatch from eggs deposited in the bark of the trees and burrow under 
the bark for a time before they enter the wood. Some species do not 
go beyond the sapwood, while others bore deep into the heartwood. 
(3) Certain stages and classes of bark-boring grubs hatching from 
eggs deposited in the bark attack the dying and dead trees, but never 
enter the wood. 
(4) Certain species and classes of wood-boring grubs attack the 
sapwood of trees dead one to three years and confine their borings 
to the sapwood. 
(5) Certain species and classes of wood-boring grubs and other 
insects enter the wood of trees dead three to twenty years or more and 
bore deep into the heartwood. 
CONDITIONS GOVERNING THE WORK OF INSECTS OF THE DIFFERENT CLASSES, 
(A) In classes 1 to 4, inclusive, the presence of bark on the trunks 
of the trees is, with a few exceptions, necessary as a receptacle for 
the eggs and as the first food of the young grubs. The exceptions are 
the pinhole borers or ambrosia beetles, which will sometimes attack 
the wood when the bark is removed, although the wood must be in a 
moist condition. The bark, however, offers far more favorable con- 
ditions for the work of this class of insects because it provides for a 
continued moist condition of the wood. 
(B) In class 5 the bark is not essential. Although offering favor- 
able conditions for the attack of some species of insects, it is not 
necessary for the attack of others, especially after the sapwood begins 
to decay. 
GENERAL METHODS OF CONTROL. 
ConpDITION A. 
To avoid damage from wood-boring insects which are dependent 
upon condition A, one or more of the following general methods 
should be adopted, so far as the local facilities and cost will permit: 
(a) Prompt utilization of the timber within 30 to 60 days after 
it is killed by fire any time from the beginning of the growth of 
vegetation in the spring until it stops in the fall, which will vary 
with latitude and altitude. Timber killed after the first snow or 
heavy frost should be utilized within 30 days after plant activity 
starts in the following spring if deterioration is to be prevented. 
(6) Prompt removal of the bark from the merchantable timber 
under the same requirements as to periods mentioned under (a). 
(ce) Placing the unbarked logs in water under the same require- 
ments as to periods mentioned under (a). 
