stiKA spruce: uses, growth, management. 21 
Forest in southeastern Alaska were defoliated by the combined activ- 
ity of sawfly larvse and caterpillars belonging to the Tineid family. 
Thus far only a small portion of the Sitka spruce in southeastern 
Alaska has been killed by this widespread defoliation. 
Occasionally aphids kill the foliage of Sitka spruce. The western 
spruce gall louse (Aphis abietina) is believed by Dr. A. D. Hop- 
kins of the Bureau of Entomology to be the aphid which caused 
the loss of the needles of Sitka spruce over thousands of acres of 
forest in 1918 in various portions of the coast region in Oregon 
and Washington. Fortunately the activity of this aphid was of 
extremely short duration, and only about 15 per cent of the in- 
fested spruce was killed. Most of this loss was confined to swamp 
and tideland areas in the lower Columbia River basin and the 
coast region and included only the poorer stands of timber. The 
Sitka spruce gall aphid (Chermes cooleyi) is found very commonly 
doing injury to Sitka spruce reproduction and occasionally causing 
its death. Large trees also are attacked, but the injury to them 
is rarely severe. These minute insects cause the development of 
conelike galls which kill the affected twigs. Infested trees of special 
value, such as those in parks and streets, may often, with good results, 
be sprayed with contact sprays like kerosene emulsion. 
Fortunately the work of defoliators does not continue more than 
a few years when it is controlled by natural agencies. Under forest 
conditions control measures against this class of insects are not 
feasible. However, defoliators greatly increase the fire hazard on 
the areas on which they have been active. Nearly always the fires 
which followed the defoliators did more damage than the insects 
themselves. The reduction of the fire risk on the defoliated areas 
is, therefore, an important consideration in defoliator problems. 
Felled timber of Sitka spruce is subject to the attacks of various 
wood borers. Logs cut between April and September are frequently 
attacked, shortly after being felled, by ambrosia beetles, sometimes 
called timber beetles or pinhole borers. These are small, elongate, 
wood-boring beetles which excavate round black tunnels, the di- 
ameter of a pencil lead, into the wood of dying trees and stumps, 
as well as logs. Investigations by the Bureau of Entomology in 
1919 showed that species of Gnathothrichus and Xyloterus commonly 
attack Sitka spruce logs, as well as western hemlock and Douglas 
fir. These borers may penetrate the wood to a depth of from 4 
to 6 inches and therefore seriously reduce the value of the sapwood, 
especially when Sitka spruce is being used for such special pur- 
poses as airplane stock. The logs which are cut in the late fall and 
winter are usually attacked in the following spring. Logs cut in 
the early fall are not entered that season; and, if piled loosely in 
