INSECT ENEMIES OF WESTERN FORESTS 141 
INSECTS INJURIOUS TO WOOD AND FOREST 
PRODUCTS 
Insects lay a heavy toll on crude and finished forest products (26, 
47, 72, 76), a loss that has been variously estimated to be from 1 
to 5 percent of the annual cut. The principal damage to forest 
products is caused by insects that feed on or bore into the wood. 
Some damage is done to wood while still in living trees, but a great 
deal occurs after trees have been killed or felled, ‘and before utiliza- 
tion; and the green or seasoned lumber, and even the final utilized 
products are fed on by insects. 
After a tree has been killed by fire, insects, or other causes, or 
felled by wind, snow, or cutting operations, it becomes particularly 
attractive to a ‘large ‘variety of insects. Ambrosia beetles find the 
dying wood with fermenting sap an especially suitable medium for 
the growth of their fungi. Horntail wasps, or wood wasps, settle on 
freshly felled trees, sometimes before the woodsmen have finished 
cutting them into logs, and on fire-killed trees before the fire is out, 
and insert their long slender ovipositors deeply into the wood to lay 
their eggs. Many of the flatheaded and roundheaded borers, 
weevils, “and larvae of carpenter moths and clear-winged moths are 
wood boring i in habit. The larvae usually feed for a time in the cam- 
bium layer “and then penetrate the wood. Fresh, unseasoned wood 
still containing sap, pitch, or other essential food elements is re- 
quired for them. In short, so many different species of wood-boring 
insects start their work on killed or felled trees that it is important 
that such timber be peeled or promptly removed from the woods 
to avoid heavy damage. 
After lumber has been kiln dried it becomes reasonably safe from 
insect attack. There are, however, a few important groups which 
still persist in their attacks unless the wood is properly handled. 
The seasoned sapwood of hardwoods is particularly susceptible to 
damage by powder-post beetles and must be carefully managed in 
the lumber yard or in storage to avoid becoming infested. ~ Even. 
after timbers are in place they are subject to attack by these insects, 
by carpenter ants, by certain roundheaded wood borers, flatheaded 
borers, and by termites unless precautions are taken to provide 
proper insulation from the ground or protection is secured through 
the impregnation of the wood with creosote or other chemicals. 
As has been indicated, the control of insects injurious to forest 
products is largely a matter of prevention of damage through cutting 
at the proper season, prompt removal of logs, poles, and stulls from 
the woods, proper handling in the mills, and certain precautions in 
utilization. Logs that are to be used for poles or in rustic work 
should be peeled before wood borers have had an opportunity to enter 
the wood. Some success has been obtained in repelling attacks of 
wood borers by spraying logs with coal-tar creosote diluted with 3 
parts of kerosene (23). In cases where logs have been attacked, the 
insects can be killed by spraying with crude orthodichlor obenzene at 
full strength or paradichlorobenzene dissolved in 3 parts, by weight, 
of kerosene (72). All such treatments, however, give only a tem- 
porary immunity. More specific methods are discussed for each of 
the different insect groups. 
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