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CIRCULAR No. 159. Issued July 27, 1912. 
United States Department of Agriculture, 
BUREAU OF ENTOMOLOGY. 
L. O. HOWARD, Entomologist and Chief of Bureau. 
DAMAGE TO THE WOOD OF FIRE-KILLED DOUGLAS FIR, 
AND METHODS OF PREVENTING LOSSES, IN WESTERN 
WASHINGTON AND OREGON. 
By AY D. Hopkins, 
In Charge of Forest Insect Investigations. 
Inquiries, with specimens, relating to extensive damage to fire- 
killed Douglas fir in western Washington showed the importance 
of making available to our correspondents some information based 
on the results of forest insect investigations. 
Douglas-fir timber killed by fire is attacked by a class of wood- 
boring insects which extend their burrows through the sound sap- 
wood and heartwood and thus contribute to the rapid deterioration 
and decay of a kind of resource which otherwise would be available 
for utilization during the periods of from 1 to 20 years or more after 
death of the trees, depending on the trees and character of product 
desired. This loss often amounts to from 25 to 100 per cent during 
the period in which the dead timber would otherwise be almost as 
valuable as living timber. 
Whenever the dying and dead timber is available for utilization 
within one to six or more years, much, and sometimes practically all, 
of the loss due to wood-boring insects is preventable. 
One class of wood-borers attacks the timber during the spring, 
summer, and fall months within the first week or two after the fire 
or after.the trees begin to die, but rarely continues to work in the 
wood for more than one year, and all of some forms of the damage, 
especially to the sapwood, is caused within 30 to 60 days, while other 
forms continue during the warm season of the first or second year, 
depending on the date of the fire and the species of insect involved. 
Most of the damage is usually confined to the sapwood, but some of 
it may extend into the heartwood. 
1 Revised circular letter of June 16, 1909, sent to interested timber-land owners. It is 
here published to supplement Forest Service Bulletin 112 on Fire-Killed Douglas Fir, 
and Bureau of Entomology Circular 127, Insect Injuries to the Wood of Dying and 
—— 
Dead Trees. 
“22168 
50687°—Cir. 159—12 
