STATE PLANT BOARD
Issued December 8, 1910.
U. S. DEPARTMENT OF AGRICULTURE,
BUREAU OF ENTOMOLOGY-CIRCULAR No. 128.
L. O. HOWARD, Entomologist and Chief of Bureau.
INSECT INJURIES TO FOREST PRODUCTS.
A. D. HOPKINS,
In Charge of Forest Insect Investigations.
64135--10 WASHINGTON : GOVERNMENT PRINTING OFFICE : 1910
BUREAU OF ENTOMOLOGY.
L. O. HOWARD, Entomologist and Chief of Bureau.
C. L. MARLATT, Assistant Entomologist and Acting Chief in Absence of Chief.
R. S. CLIFTON, Executive Assistant.
W. F. TASTET, Chief Clerk.
F. H. CHITTENDEN, in charge of truck crop and stored product insect investigatins.
A. D. HOPKINS, in charge of forest insect investigations.
W. D. HUNTER, in charge of southern field crop insect investigations.
F. M. WEBSTER, in charge of cereal and forage insect investigations.
A. L. QUAINTANCE, in charge of deciduous fruit insect investigations.
E. F. PHILLIPS, in charge of bee culture.
D. M. ROGERS, in charge of preventing spread of moths, field work.
ROLLA P..CURRIE, in charge of editorial work.
MABEL COLCORD, librarian.
FOREST INSECT INVESTIGATIONS.
A. D. HOPKINS, in charge.
H. E. BURKE, J. L. WEBB, JOSEF BRUNNER, S. A. ROHWER, T. E. SNYDER, W. D.
EDMONDSTON, agents and experts.
MARY E. FAUNCE, preparator.
WILLIAM MIDDLETON, MARY C. JOHNSON, student assistants.
CIRCULAR NO. 128. Issued December 8, 1910.
United States Department of Agriculture,
BUREAU OF ENTOMOLOGY.
L. O. HOWARD, Entomologist and Chief of Bureau.
INSECT INJURIES TO FOREST PRODUCTS.a
By A. D. HOPKINS,
In Charge of Forest Insect Investigations.
Damage is caused by various species of insects which are attracted
by the varying conditions prevailing at different stages during the
process of utilizing the forest resources, from the time the trees are
felled until the logs are converted into the crude and finished product
and until the latter reaches the final consumer, or even after it is
placed in the finished article or structure. As a result, additional
drains are made on the timber to meet the demand for the higher
grades of lumber and for other supplies to replace those injured or
destroyed. From the writer's personal investigations of this subject
in different sections of the country it is evident that the damage to
forest products of various kinds from this cause is far more extensive
than is generally recognized. This loss differs from that resulting
from insect damage to standing timber in that it represents more
directly a loss of money invested in material and labor.
Roundheaded borers, timber worms, and ambrosia beetles.-Round
timber with the bark on, such as poles, posts, mine props, saw "logs,
etc., is subject to serious damage by the same class of insects as those
mentioned under injury to the wood of dying and dead trees. The
damage is especially severe when material is handled in such a man-
ner as to offer favorable conditions for attack, as when the logs are
left in the woods on skidways or in millyards for a month or more
after they have been cut from the living trees. Under such condi-
tions there is often a reduction in value of from 5 to 30 per cent or
more, due to wormhole and pinhole defects caused by roundheaded
and flatheaded wood-borers and timber beetles. Frequently the
insects continue the work in the unseasoned and even dry lumber
cut from logs which had been previously infested. They also con-
a Revised extracts from Bulletin No. 58, Part V, Bureau of Entomology, U. S.
Department of Agriculture, 1909.
64135--Cir. 128-10 1
2 INSECT INJURIES TO FOREST PRODUCTS.
tinue to work in mine props after they have been placed in ne
and in logs and other material used for the construction of
rustic houses, etc., and in round timbers generally.
The products from saplings, such as hickory hoop poles and like
material, are often seriously injured or rendered worthless by round-
headed and flatheaded borers and wood-boring beetles, sometimes
resulting in a loss of from 50 to 100 per cent of the merchantable
Stave and shingle bolts left in moist, shady places in the woods or
in close piles during the summer months are often attacked by
ambrosia beetles and timber beetles. The value of the proluct is
often reduced, as a consequence, from 10 to 50 per cent or more.
Handle and wagon stock in the rough is especially liable to injury
by ambrosia beetles and roundheaded borers. Hickory and ash bolts
from which the bark is not removed are almost certain to be greatly
damaged if the logs and bolts cut from living trees during the winter
and spring are held over for a few weeks after the middle of March
or first of April.
Pulp wood, and cord wood for fuel and other purposes, cut during
the winter and spring and left in the woods for a few weeks or
months or in close piles after the beginning of the warm weather, are
sometimes riddled with wormholes or converted into sawdust borings,
causing a loss of from 10 to 100 per cent. One example reported
from near Munising, Mich., represents a loss of $5,000 from injury to
spruce and fir pulp wood cut in the winter and kept in piles over
MANUFACTURED UNSEASONED PRODUCTS.
Ambrosia beetles and other wood borers.-Freshly sawed hard-
wood placed in close piles during warm, damp weather during the
period from June to September is often seriously injured by am-
brosia beetles. Heavy 2-inch to 3-inch stuff is also liable to attack
by the same insects, even in loose piles. An example of this was
found in some thousands of feet of mahogany lumber of the highest
grade, which +had been sawed from imported round logs and piled
with lumber sticks between the tiers of plank. Native species of
ambrosia beetles had entered the wood to such an extent as to have re-
duced the value 50 per cent or more within a few weeks. Oak, poplar,
gum, and similar woods often suffer severe from this class of nury,
causing losses varying from 5 to 50 per t.
Lumber and square timbers of both soft and hard woods wit
bark left on the edges are frequently damaged by flatheaded a
roundheaded wood borers, which hatch from egs depoited in th
bark before or after the lumber is sawed. There are examples of
INSECT INJURIES TO FOREST PRODUCTS. 3
losses from this character of injury amounting to from 20 to 50 per
cent or more.
Telegraph and telephone poles, posts, mine props, etc., are fre-
quently injured before they are set in the ground, especially if the
bark remains on them during a few weeks after the middle of March.
SEASONED PRODUCTS IN YARDS AND STOREHOUSES.
Powder-post beetles.-Hardwood lumber of all kinds, rough
handles, wagon stock, etc., made partially or entirely of sapwood, are
often reduced in value from 10 to 90 per cent by a class of insects
known as powder-post beetles. The sapwood of hickory, ash, and
oak is most liable to attack. The reported losses from this source
during the past five or six years indicate that there has been an
average reduction in values of from 5 to 10 per cent or more.
Old hemlock and oak tanbark is often so badly damaged by vari-
ous insects which infest dead and dry bark that in some tanyards as
much as 50 to 75 per cent of the bark that is over three years old is
destroyed. In one tannery in West Virginia it is estimated that more
than $30,000 worth of hemlock bark was thus destroyed.
The greatest loss of finished hardwood products, such as handle,
wagon, carriage, and machinery stock, is caused by powder-post
beetles. This is especially true of hickory and ash handles and like
products in the large and small storehouses of the country, including
the vast amount of material held in storage for the army and navy.
When material of this kind is once attacked it is usually worthless
for the purposes indicated, and therefore must be replaced with new
material. In some cases losses have amounted to from 10 to 50 per
cent, and it is estimated that the average losses have been as much as
10 per cent on nearly all sapwood material that has been in storage
more than one year.
Powder-post bettles, white ants, and other wood-boring insects.-
The finished woodwork in implements, machinery, wagons, furniture,
and the inside finish in private and public buildings are often seri-
ously damaged by powder-post beetles, thus requiring increased de-
mands for new material.
Construction timbers and other woodwork in new and old build-
ings are often so seriously damaged by powder-post beetles, white
ants, and other wood-boring insects that the affected material has to
be removed and replaced by new, or the entire structure torn down
STATE PLANT BOARD
4 INSECT INJURIES TO FOREST PRODUCTS.
Construction timbers in bridges and like structures, railroad tie
telephone and telegraph poles, mine props, fence posts, etc., are some-
times seriously injured by wood-boring larve, termites, black ants,
carpenter bees, and powder-post beetles, and sometimes reduced in
value from 10 to 100 per cent.
PREVENTION OF INSECT INJURIES TO FOREST PRODUCTS.
The problem of artificial control and prevention of insect injuries
to forest products offers less difficulties perhaps than that relating
to many other branches of the general subject of forest-insect control.
In most cases the principle of prevention is the only one to be con-
sidered, since the damage is done soon after the insects enter the
wood, and therefore it can not be repaired by destroying the enemy.
The proper degree of moisture found in the bark and wood of
newly felled trees, saw logs, telegraph poles, posts, and like material,
cut in the fall and winter and left on the ground or in close piles
during a few weeks or months in the spring and summer or during
the period when the particular species of injurious insects are flying,
are some of the conditions most favorable to attack. The period of
danger varies with the kind of timber and the time of the year it is
felled. Those felled in late fall and winter will generally remain
attractive to ambrosia beetles and adults of round and flat headed
borers during March, April, and May. Those felled during the
period between April and September may be attacked in a few days
after they are felled, but the period of danger from a given species
of insect may not extend over more than a few weeks. Thus certain
kinds of trees felled during certain seasons are never attacked, while
if they are felled at other times and seasons the conditions for attack
may be most favorable when the insects are active, and then the wood
will be thickly infested and ruined. The presence of bark is abso-
lite ly necessary for successful infestation by most of the wood-boring
grubs, because the eggs and young stages must occupy the inner
and outer portions before the latter can enter the wood. Some
ambrosia beetles and timber worms will, however, attack barked logs,
especially those in close piles or otherwise shaded or protected from
rapid drying. A large percentage of the injury to this class of
products can be prevented, as follows:
(1) Provide for as little delay as possible between the felling of the
tree 1and its m1nu1facture into rough products. Thi is especially
necessary with trees felled from April to September in the region
north of the Gulf States and from March to November in the latter,
INSECT INJURIES TO FOREST PRODUCTS. 5
while the late fall and winter cuttings should all be worked up by
March or April.
(2) Do not leave the round timbers in the woods or on the skid-
ways during the danger period, or, if this is unavoidable, take every
precaution to facilitate the rapid drying of the inner bark by keeping
the logs off the ground, in the sun, or in loose piles, or else, if possible,
the opposite extreme should be adopted and the logs kept in water.
(3) Remove the bark within a few days after the trees are felled,
from poles, posts, and other material which will not be injured by
checking or season cracks.
(4) Take advantage of the proper months or seasons in which to
fell or girdle different kinds of trees to avoid danger.
Damage to products cut from saplings and left with the bark on
can be prevented by transporting the material from the woods soon
after it is cut, so that it will not be left in piles or bundles in or near
the forest during the season of insect activity. Damage may also be
prevented if care is taken not to leave the material stored in one place
for several months.
Pinhole damage to stave and shingle bolts cut during a warm season
can be prevented by removing the bark from the timber as soon as it
is felled and by converting the bolts into the smallest practicable
dimensions and piling them in such a manner as to facilitate rapid
Damage to unseasoned handle and wagon stock in the rough can be
prevented by taking special precautions to provide against the same
favorable conditions for attack as mentioned in connection with round
timbers. This is especially necessary with hickory and ash if cut
during the winter and spring.
Damage to pulpwood and cordwood can be prevented to a great
extent by placing the sticks of wood in triangular or crib piles imme-
diately after they are cut from the trees, especially if the timber is cut
during the danger period, or must be held for a few months during the
warm season. Peeling or splitting the wood, or both, before it is
piled will also provide against damage from insects.
Freshly sawed hardwood lumber placed in close piles during warm,
damp weather in the period from July to September, inclusive, pre-
sents the most favorable conditions for injury by ambrosia beetles.
In all cases it is the moist condition and retarded drying of the lum-
ber which induces attack. Therefore any method which will provide
for the rapid drying of the lumber before or after piling will tend
6 INSECT INJURIES TO FOREST PRODUCTS.
to prevent loss. It is important, also, that heavy lumber shoul
as far as possible, be cut only in the winter and piled so that it will
be well dried out before the middle of March.
The damage to lumber and square timber when the bark is left on
the edges or sides can be prevented by removing the bark before or
immediately after the lumber is sawed, or by sawing and piling the
material during the winter, or if sawed at other times it should be
piled so that rapid drying will be facilitated.
Unfinished seasoned products.-Injury by powder-post beetles to
dry hardwood lumber and other material in stacks or storehouses can
be prevented as follows:.
(1) Have a general inspection of the material in the yards and
storehouses at least once a year, preferably during November or
February, for the purpose of (a) sorting out and destroying or other-
wise disposing of any material that shows the slightest evidence of
injury, as indicated by the presence of fine powdery boring dust, and
(b) sorting out and destroying all old and useless sapwood material
of any kind that will offer favorable breeding places for the insects.
(2) Prevent the introduction into the lumber yards or storehouses
of any infested material, remembering that the insect may be thus
distributed to or from all parts of the world.
(3) Adopt a system of classification of all dry or seasoned hard-
wood stock which will provide for (a) the separation of the pure
heartwood material from the pure and part sapwood material; (b)
classification of all kinds of wood most liable to attack, such as hick-
ory, ash, oak; (c) the successive utilization or sale of the older ma-
terial (remembering that material one year old or over is far more
liable to injury); (d) providing against the accumulation of refuse
material in which the insects could breed; and (e) treating the best
material with linseed oil or kerosene to prevent attack.
Finished seasoned products.-Damage to finished handles, oars,
spokes, rims, hubs, wheels, and other unpainted wagon, carriage,
machinery, and implement stock in factories, wholesale and retail
storehouses, and army and navy stores can be prevented by the adop-
tion of the same general rules as those given under rough products.
In addition, damage can be controlled and prevented in the following
Sort out and (a) destroy all articles showing the slightest evidence
of powder-post injury, or (b) treat with kerosene oil such infested
and slightly injured articles as may be tested for required strength
and folud to be of sufficient value for retention, placing the same in
lquaranhtine for a sufficient time to deterine whether the treatment is
INSECT INJURIES TO FOREST PRODUCTS. 7
Damage by powder-post insects to many kinds of articles can be pre-
vented and at the same time the material otherwise benefited by treat-
ing the sapwood with linseed oil or kerosene, either by immersing it
in the oil or by applying the oil with a brush, the application to be
made as soon as possible after the articles are finished from recently
seasoned, uninjured stock.
PAST AND PRESENT CONDITIONS OF POWDER-POST INJURY.
Up to 1906 there were a great many reports of extensive losses of
valuable material from the ravages of powder-post beetles which
were seriously affecting all industries involved in the manufacture,
sale, and utilization of the classes of hardwood products affected by
them. In response to these reports and accompanying appeals to the
Department of Agriculture for information on causes and remedies,
the problem was thoroughly investigated and specific advice and in-
structions relating to practical methods of control and prevention
have been widely disseminated, both through publications of the
Department and special correspondence.
Reports of present conditions from our principal correspondents,
together with the less frequent requests for advice, indicate that
the disseminated information has been extensively utilized and that
it has been worth many millions of dollars toward eliminating the
losses and reducing the drain on the limited supply of the kinds of
timber required to replenish the damaged and destroyed material.
The army and navy stores of handles, tent poles, wheelbarrows,
oars, and many other hardwood articles have suffered severely from
powder-post damage, involving an enormous loss, but the carrying
out of the information already supplied has evidently contributed
greatly toward the elimination of this source of loss to the Gov-
Damage to hemlock and oak tan bark by the class of insects which
in some cases has been so destructive to these products in the past can
be easily prevented without cost, as follows:
(1) Utilize the bark within three years from the time it is taken
from the trees.
(2) Prevent the accumulation in the yards and store sheds of old
bark and waste material in which the insects can breed.
These simple methods Have been extensively adopted since their
recommendation in correspondence and publications between about
1894 and 1904, and afford one of the most striking examples of the
value of expert information on the peculiar habits of insects and of
how millions of dollars can be saved without cost thiough a simple
adjustment in methods of utilization.
8 INSECT INJURIES TO FOREST PRODUCTS.
Damage and loss from insect injuries to timber and other woodwork
in structures of various kinds, to telephone and telegraph poles, posts,
railroad ties, mine props, etc., can be prevented to a large extent
through the adoption of the proper methods of management or of
treating the material with preservatives before and after it is utilized.
TIMBERS AND WOODWORK IN STRUCTURES.
Injuries to timbers and woodwork in dwellings, outbuildings,
bridges, etc., by powder-post insects can be prevented as follows:
(1) Use nothing but heartwood for the concealed parts most liable
(2) If it is necessary to use all or part sapwood material, attack
can be prevented by treating the sap portions with kerosene, coal tar,
creosote, or linseed oil. Facilities for future treatment can be pro-
vided wherever the rough or finished woodwork is exposed, as in
outbuildings, bridges, etc., if care is taken to expose the sapwood
(3) If the untreated timbers and woodwork in old buildings show
evidence of attack, the affected portions should be given a liberal
application of kerosene.
Damage by white ants, or termites, can often be prevented in the
(1) By the use of nothing but sound wood for underpinning and
foundation timbers and the removal of decaying timbers from old
(2) By preventing moist conditions of the wood in any part of the
structure and especially that in foundation timbers.
(3) By the treatment of timbers necessarily exposed to moist con-
ditions with creosote, zinc chlorid, corrosive sublimate, etc.
(4) If the timbers become infested, further progress of insect dam-
age can be prevented by removing the badly damaged parts and soak-
ing the remainder with kerosene, fumigating with bisulphid of
carbon, and by removing any adjacent decaying or other wood in
which the insects have been breeding or may breed, such as logs,
Log cabins and rustic work.-Damage by bark and wood boring
insects to the unbarked logs and poles used in rustic cabins, summer
houses, fences, etc., can be largely prevented by cutting the material
in October and November and utilizing it at once, or by piling it off
the ground or under cover in such a manner as to offer the best facil-
ities for the rapid and thorough drying of the inner bark before the
middle of March or the 1st of April following. If these necessary
INSECT INJURIES TO FOREST PRODUCTS. 9
precautions are not taken, and there is evidence that insects are at
work in the bark and wood, the damage can be checked by injecting
bisulphid of carbon through natural or artificial openings in the
affected bark, and immediately stopping these and other openings
with putty or a similar substance.
Poles, posts, piles, ties, mine props, and similar products.-Insect
damage to poles, posts, and similar products can be prevented to a
greater or less extent by the preservative treatments which have been
tested and recommended by the Forest Service for the prevention of
decay. These should be applied before the material is utilized for
the purposes intended, or, if it be attacked after it has been utilized"
further damage can be checked to a certain extent by the use of the
It is often of prime importance to prevent injury from wood-
boring insects, for the reason that such injuries contribute to more
rapid decay. Therefore anything that will prevent insect injury,
either before or after the utilization of such products, will contribute
to the prevention of premature deterioration and decay.
Secretary of Agriculture.
WASHINGTON, D. C., October 7, 1910.
UNIVERSITY OF FLORIDA
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