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CIRCULAR No. 127. Issued December 7, 1910.

United States Department of Agriculture,

BUREAU OF ENTOMOLOGY.

L. O. HOWARD, Entomologist and Chief of Bureau.

INSECT INJURIES TO THE WOOD OF DYING AND DEAD
TREES.“

By A. D. HorPxKins,
In Charge of Forest Insect Investigations.

Timber dying from insect attack and other causes, including fire,
disease, storms, etc., is attacked by certain wood-boring insects which
extend their burrows through the sound sapwoed and heartwood, and
thus contribute to the rapid deterioration and decay of a commodity
which otherwise would be available commercially during periods of
from one to twenty years or more after the death of the trees, depend-
ing on the species of trees and on the character of the 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 if
living.

CONIFEROUS TREES.

Sawyers.—One of the most striking examples of the destruction or
deterioration of the wood of dying and dead timber, familiar to all
lumbermen, is the injury to fire-killed and storm-felled pine, fir,
spruce, etc., caused by boring larve known as “sawyers.” These
borers hatch from eggs deposited by the adult beetles in the bark of
the dying trees, and after feeding on the inner bark for a time they
enter the solid wocd and extend their large burrows deep into the
heartwood. Fire-killed white pine is especially lable to this injury,
and is often so seriously damaged within three or four months during
the warm season as to reduce the value of the timber 30 to 50 per cent.
The shortleaf, loblolly, and longleaf pines of the Southern States are

4 Revised extracts from Bulletin No. 58, Part V, Bureau of Entomology, U. 8.
Department of Agriculture, 1909.
64138°—Cir. 127—10 (>

21S 3524

2 INSECT INJURIES TO WOOD OF DYING AND DEAD TREES.

damaged to a somewhat less extent, but instances are known in which
more than one billion feet of storm-felled timber within limited areas
were reduced in value 25 to 35 per cent within three months after the
storm. The fire-killed and insect-killed sugar pine, silver pine, and
yellow pine of the western forests are also damaged in a similar man-
ner and the value of the product greatly reduced within a few months
after the trees die. The aggregate losses from this secondary source
in the coniferous forests of the entire country contribute largely to the
annual waste of millions of dollars’ worth of forest products which
otherwise might be utilized.

Ambrosia beetles —W ood-boring insects of another class, known as
timber beetles or ambrosia beetles, cause pinhole defects, principally
in the sapwood, although some of them extend their burrows into the
heartwood. These insects make their attack in the early stage of the
declining or dying of the tree, or before the sapwood has materially
changed from the normal healthy condition, and often in such num-
bers as to perforate every square inch of wood. Thus the wood is
not only rendered defective on account of the presence of pinholes,
but the holes give entrance to a wood-staining fungus which causes a
rapid discoloration and produces still further deterioration of the
product.

The sapwood of trees dying from the attack of other insects or
from fire, storm, or other causes is often reduced in value 50 per cent
or more, and in some cases the value of the heartwood is reduced in a .
like manner from 5 to 10 per cent.

Pinhole borers in cypress—An example of the destructive work
of insects which attack dying and dead trees is found in the cypress
in the Gulf States, where these trees are deadened by the lumbermen
and left standing several months, or until the timber is sufficiently
dry to be floated. Upon investigation it was found that trees dead-
ened at certain seasons of the year were attacked by the ambrosia
beetles, or pinhole borers, and that in some cases millions of feet of
timber had been reduced 10 to 25 per cent or more in value.¢

HARDWOOD TREES.

Roundheaded borers, timber worms, and ambrosia beetles—The
principal damage to dying and dead hardwood trees is caused by cer-
tain roundheaded wood-borers (Cerambycide) with habits similar to
the sawyer, by the timber worms mentioned as damaging living tim-
ber, and by ambrosia beetles having habits similar to those that attack
the sapwood and heartwood of conifers. All of the hardwoods suffer
more or less, but.the greatest damage is done to the wood of hickory,

“For methods of preventing pinhole injury to girdled cypress see Circular No.
82 of the Bureau of Entomology, U. S. Department of Agriculture.
[Cir. 127]

>
,

INSECT INJURIES TO WOOD OF DYING AND DEAD TREES. 3

ash, oak, and chestnut, which are often reduced in value 10 to 25 per
cent or more within the period in which it would otherwise remain
sound and available for commercial purposes.

PREVENTION OF INJURY TO DYING AND DEAD TREES.

A large percentage of the injury to the wood of insect, fire, and
lightning killed trees and those killed or dying from injuries by
storms, disease, etc., can be prevented as follows:

(1) By the prompt utilization of such timber within a few weeks
or months after it is dead or found to be past recovery.

(2) By removing the bark from the merchantable portions of the
trunks within a few weeks after the trees are dead (the work to be
done either before or after the trees are felled).

(3) By felling the trees and placing the unbarked logs in water.

(4) By the adoption of a system of forest management which will
provide for the prompt utilization of all trees which die from any
cause.

Approved:

JAMES WILSON,
Secretary of Agriculture.

Wasuineton, D. C., October 7, 1910.

[Cir. 127]

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