|Table of Contents|
Table of Contents
I......... .. . ... 1
N.. 1*, ,
9 1 *1- -^
U. S. DEPARTMENT
BUREAU OF ENTOMOLOGY- BULLETIN No. 94. Part, L
L. 0. HOWARD. Eniomologist and Chief4 of Bume
INSECTS INJIURIOH I 8 TO FORlESTr A
FOREST I'RFO)I "S.
DAMAGE TO CHESTNUT TI'LElHINE AND
TELEGRAPH I'POIES BY WOOD-
THOMAS E. SNYDER, .M. F.,
Agnt rand I'}'.rir/.
ISSUED DECEMBER 31, 1910.
GOVERNMENT PRINTING OFFICE.
-- w r" I"''I11 "
BUREAU OF ENTOMOLOGY.
L. 0. HOWARD, Entomologist and Chief of Bureau.
C. L. MARLATT, Assistant Entomologist and Acting Chief in Absence of Chief.
R. S. CLIFTON, Executire Assistant.
W. F. TASTET, Chief Clerk.
F. H. CIHITTENDEN, in charge of truck crop and stored product insect
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.
EDMONSTON, agents and expert.
MARY E. FAUNCE. preparator.
WILLIAM MIDDLETON, MARY C. JOHNSON, student assistants.
.. ": *
O NT I N' S.
O bject of papera...............................................
The chestnut telephone-pole borer ('arandra brunnea Fab. ------.......
Character of the insect ....................................
D distribution ........................................ ......
Character of the injury.......... ...........................
Importance of the problem.................................
Extent of damage and loss..................................
Favorable and unfavorable conditions for destructive work..
Associated wood-boring insects.................................
Prevention of the injury........................................
Publications on wood preservation and statistics on poles.........
INSECTS INJURIOUS TO FORESTS.
badly injured by borers and that these borers were abundant. On
March 8, 1907, he.collected larvmae from chestnut telephone poles at
Pennsboro, W. Va. These were determined to be the larvae of the
chestnut telephone-pole borer.
The writer on October 3, 1909, inspected some chestnut telegraph
poles which had been standing for about twelve years on New York
avenue, in Washington, D. C. The poles had been taken down under
orders from the city authorities, which necessitated the placing of
wires in conduits under ground, and they had been lying in piles for
about a month before they were inspected. The chestnut telephone-
pole borer had been working in the base of the poles, and white ants,
or termites, were associated with them. Twelve out of the 103 poles
examined had been damaged, some more seriously than others.
On October 15, 1909, Mr. H. E. Hopkins sent a reply to a request
by Dr. A. D. Hopkins for further information regarding insect dam-
age to poles in West Virginia. He stated that in one line built twelve
years ago (40 miles long, 36 chestnut poles to the mile, poles 20 to
40 feet long and 5 to 12 inches in diameter at the top) approximately
600 poles had been rotted off at the top of the ground, and inspection
showed that 95 per cent of the damage was directly or indirectly
due to insects. Other lines in this division were reported to be in
about the same condition. It was later determined that most of the
insect damage was the work of the chestnut telephone-pole borer.
Dr. A. D. Hopkins states in a recent comprehensive bulletin a that
"construction timbers in bridges and like structures, railroad ties,
telephone and telegraph poles, mine props, fence posts, etc., are
sometimes seriously injured by wood-boring larvae, termites, black
ants, carpenter bees, and powder-post beetles, and sometimes reduced
in efficiency from 10 to 100 per cent." Thus, while it has been known
that almost all classes of forest products that are set in the ground
are seriously injured by wood-boring insects, the problem of insect
damage to standing poles, posts, and other timbers has never been
made the subject of a special investigation.
In May, 1910, this study was assigned to the writer, and, in addi-
tion to a study of the insects involved, investigations in cooperation
with telephone and telegraph companies have been conducted in the
District of Columbia, Maryland, Virginia, Pennsylvania, New Jersey,
and New York. Through the courtesy of the Western Union Tele-
graph Company several telegraph lines were inspected in July and
August, 1910, in Virginia, where the poles were being reset or replaced.
Here the butts of over 200 poles set under different conditions of
site were thoroughly examined for insect damage, and sometimes the
a Insect Depredations in North American Forests.
Bul 44 P.j 1 I. Burlju of Entum.,lhy. U. S. D'pt of Ao,.rcullure
FIG. 1 .-THE CHESTNUT TELEPHONE-POLE BORER (PARANDRA BRUN-
NEA): MALE AND FEMALE BEETLES. FIG. 2.-THE CHESTNUT
TELEPHONE-POLE BORER: YOUNG LARV,.E, DORSAL AND LATERAL
VIEWS. FIG. 1, SLIGHTLY ENLARGED; FIG. 2, TWICE NATURAL
FIG. 3.-DAMAGE TO AN UNTREATED CHESTNUT TELEGRAPH POLE
NEAR SURFACE OF GROUND BY THE CHESTNUT TELEPHONE-POLE
DAMAGE TO CHESTNUT POLES BY INSECTS. 3
entire pole was split open. In 0n1( line 10 to 12 veiars (old (aj)l)roxi-
mately 30 chestnut poles per mile, 25 feet long, abIouit (6 ilclies diam-
eter at the top, 10 inches at the base, andl aIl)p)arelit ly of seco(.d! qualityy),
between Petersburg and Crewe, Va.-the les had i alr'aldy 1,iel reset
once, east of Wilson, Va.-serious damage lby tlie chestnut tliphonice-
pole borer rendered from 15 to 20 per cent of tlie poles unserviceable.
After the present second resetting it was esti-
mated that. the poles can not last more than
four or five years longer. West of Wilson the I
poles were naturally in much worse condition, .
and many were broken off and only held up 2
by the wires on the sounder poles. In another 6
line examined, between Portsmouth and Boy-
kins, Va. (poles 30 feet long and apparently of
second quality), serious damage by this borer
averaged about 10 or 15 per cent, and between
Boykins, Va., and Weldon, N. C., according to
a linesman, 50 per cent of the poles are badly
decayed near the surface of the ground.
Much of this damage, however, is due to fun- FIG.I.-Thechestnuttelephone-
pole borer Parandra brunnea):
gous heart rot. According to a statement, Full-grown larva, iA bout
by the foreman of a resetting crew, between twicenaturalsize. (Original.)
Asheville, N. C., and Spartanburg, S. C., hundreds of chestnut poles
were badly decayed in the 67 miles of line reset, and were only held
up by the wires. The line was 15 years old. There was serious
damage by "wood lice" (termites) and also by "white wood worms."
THE CHESTNUT TELEPHONE-POLE BORER.
(Parandra brunnea Fab.)
CHARACTER OF THE INSECT.
The chestnut telephone-pole borer is a creamy white, elongate,
stout, cylindrical, so-called "round-headed" grub or "wood worm"
(fig. 1), which hatches from an egg deposited by an elongate, flattened,
shiny, mahogany brown, winged beetle from two-fifths to four-fifths of
an inch in length. (Plate I, fig. 1; text fig. 2.) The eggs are probably
deposited from August to October in shallow natural depressions or
crevices on the exterior of the pole near the surface of the ground;
often the young larvae enter the heartwood through knots. The
young borers (Plate I, fig. 2) hatching therefrom eat out broad
shallow galleries running longitudinally in the sapwood, then enter
the heartwood, the mines being gradually enlarged as the larvae
develop. As they proceed, the larvae closely pack the fine excreted
boring dust behind them. This de6bris, which is characteristic of
INSECTS INJURIOUS TO FORESTS.
their work, is reddish to dunnish yellow in color and has a claylike J
consistency. The mines eventually end in a broad chamber, the
entrance to which is plugged up by the excelsior-like fibers of wood
chiseled out by the strong mandibles of the larva. Here the resting
stage (fig. 3), or pupa, is formed, and in this chamber the perfect adult .j
spends considerable time before emerging. Often all stages from very
young larvae only about one-fourth inch long to full-grown larvae over
1 inch long, pupae, and
adults in all stages to
)S. maturity are present in M
^t b^the same pole. Adultsr ....
.... > have been found flying
from July to Septemd,:,
f ber. As yet the sea-
Z sonal history of this
'^ B ^borer has not been con- ,
,H "-' a~ pletely worked out.
FmG. 2.-The chestnut telephone-pole borer: Female beetle, three This insect is very
and one-half times natural size. Head and pronotum of male widely distributed,
beetle. (Original). ranging from Ontario,
ranging from Ontario, j
Canada, to Texas, eastward to the Atlantic coast, and westward to .
Arizona and southern California. It is common throughout the :
natural range of the chestnut-and in this connection it should be WE
observed that most of the chestnut poles are purchased from locals:
timber-land owners. .
CHARACTER OF THE INJURY.
The injury to the poles consists in large mines in the wood near the
line of contact of the pole with the ground, necessitating the frequent
resetting or even the replacement of the damaged poles. These
irregular galleries of the grub (Plate II, fig. 1) run both horizontally,
and longitudinally throughout the heartwood, and are sometimes 7
inches long, but vary with the individuals, which show great differ-
ences in size. The borers usually work in the outer layers of the
wood at the base of the pole for a distance of from 2 to 3 feet below,
and sometimes from 1 to 2 feet above the line of contact of the pole
with the surface of the ground. The greatest damage is to that area l
just below and just above the surface of the ground (Plate I, fig. 3);
here the conditions of air and moisture are most favorable. Often
the entire butt up to a distance of from 4 to 6 feet and higher,
according to the depth of setting, is mined. The numerous galleries, I
often very close together, completely honeycomb the wood in a zone
Bul. 94. Part I 1. Bureau of EnlmoIlofy. U S DL.p cif Ai,,c uullut
WORK OF THE CHESTNUT TELEPHONE-POLE BORER.
Fig. 1.-Gallery of the chestnut telephone-pole borer, showing pupal chamber with the en-
trance plugged with excelsior-like wood fibers; work near base of pole, below ground.
Fig. 2.-Mines of the chestnut telephone-pole borer near surface of ground. Natural size.
DAMAGE TO CHESTNUT POLES BY INSECTS.
3 to 4 inches in from the exterior of thfi, poles; this so weakens tie
poles that they break off close to the surface of tlie ground. 'lThe
basal 2 feet is usually sound. Even if tle (lalmge is ot serious
enough to cause the poles to break olff under strain, tihey are likely to
go down during any storm, and thus put tlhe wire service outI of com-
mission; such damaged poles are a serious menace along tlie, right of
way of railroads. The beetle will attack poles tlhat are perfectly
sound, but evidently prefers to work where the woodl shows signs of
incipient decay; it will not work in wood that is "'sobh y" (wet rot),
or in very "doty" (punky) wood. It has not yet l)een (letermilned
just how soon the borers usually enter thle poles after they liave been
set in the ground. However, poles that had been standing only four
or five years contained larvae and adults of this borer
in the heartwood, and poles that had been set in the
ground for only two years contained young larvae in the
outer layers of the wood.
Poles that appear sound on the exterior may have the
entire basal interior riddled, and the work of the borers
is not noticed until the poles break off. If merely iso-
lated poles are injured, the poles that are broken off are 3
held up by the wires and can be detected by the fact
that they lean over, but if several adjacent poles are
affected, especially where there is any unusual strain,
that portion of the line is very likely to go down. The
presence of the borers in injurious numbers can be de-
termined only by removing the earth from about the FIG. 3.-The
base of the pole; the exit holes of the borer are found phone-pole bor-
near the line of contact with the soil. Often large, er: Pupa.
coarse borings of wood fiber project from the exit holes, than twice
Sometimes old dead parent adults are found on the natural size.
1 1 -rt *(Original.)
exterior of the poles underground. During August the (Original.)
young adults may be found in shallow depressions on the exterior of
poles below the ground surface.
IMPORTANCE OF THE PROBLEM.
The subject of the relation of insects to the rapid decay of chestnut
poles has not been thoroughly investigated in the past, but now that
the supply is becoming scarcer it is especially important to know
what are the various primary causes of the deterioration of these
poles, hitherto described under the vague term "decay." Although
the chestnut telephone-pole borer has not hitherto been considered an
insect of any economic importance, and has been described in ento-
mological literature as only living under bark, principally of pine, or
INSECTS INJURIOUS TO FORESTS.
in the decomposing wood of various species of deciduous and conif-
erous trees, the evidence is abundant that breeding in the bases of
chestnut poles is not a newly acquired habit. It has also been
determined that this beetle damages many species of living forest,
fruit, and shade trees that have been previously injured by fire or
other causes, and often leads to the destruction of trees that would
otherwise recover from such wounds, and while not normally a
l)rimary enemy to trees, may thus become of more than secondary
The damage by the chestnut telephone-pole borer is especially
serious in consideration of the fact that in many parts of its range the
chestnut is threatened with extinction as a tree species on account of
the very severe ravages of the combined attack of an insect a and a
fungous disease. Further unnecessary drain upon the supply of
chestnut timber should be avoided by protecting that already in use
and thus prolonging its length of service.
EXTENT OF DAMAGE AND LOSS.
As more than one-fourth of the 3,500,000 round poles exfdling 20
feet in length used annually by telephone, telegraph, anJ other
electric companies are chestnut (Kellogg, 1909),b and as this borer
has seriously damaged as high as 10 to 40 per cent, varying with
conditions of site, of the chestnut poles which have been set in the
ground for from ten to twelve years in lines in North Carolina, Virginia,
West Virginia, Maryland, and the District of Columbia, it is evident
that this insect is an important factor in decreasing the normal
length of service of the poles.c In lines from twelve to fifteen years
old the damage is much greater, and at the end of this number of
years of service any line in which poles of this species are set has to
be practically renewed. According to a statement in Forest Service
Bulletin 78 (Sherfesee, 1909), "approximately 4 per cent, or 5,908
feet board measure of the 147,720 feet board measure of standing
poles annually requiring replacement in the United States, is destroyed
by insects." If only chestnut poles be considered, at least 10 per
cent of the poles reset or replaced are injured by insects.
FAVORABLE AND UNFAVORABLE CONDITIONS FOR DESTRUCTIVE WORK.
The damage is apparently greatest and the borers are most abun-
dant where the poles are set in high or level dry ground under good
conditions of drainage. Such sites are the crests of railroad cuts a!
through low hills, slopes of "fills," and in cultivated or other fields.
Where the poles are in wet sites there is usually but little injury by
Agrilus bilineatus Web.
b See list of publications, page 11.
c The average life of a chestnut pole is eight to ten years (Sherfesee and Weiss, 1909).
DAMAGE TO CIIESTNUT POLES BY INSEAICTS. 7
wood-boring insects except to talit p)orti0 lll near tl Mi.,rb'lt'( Of tli1
|ground. Condit ions( f drainage are Imore ipll)ortanlt tl13M lil'l'Irlnt
soil combinations, anl tihe conmidition ()f tie soil is i1m H r111 ipll(Irt -1it,
than its compositionl; ;. '., where. tim soil is hard Jac'kdl It( ire is
apparently less damage thlian where it is loose. Thie quality aitNd con-
dition of the poles before setting is a very important factor to ,'on-
11 sider before arriving at any conclusions aits to tlie relative loigevit of,
J poles under varioutis conditions of site. Green (unseasow e) r im-
B perfectly seasoned poles are less durable than tll)hose tinro)(ughly
seasoned. Poles that are defective before setting, as they verv
i often are (i. e., showing evidence of incipient decay), and poles thIat
have the heartwood mined by the chestnut tillmber wormn t le wirk
of which is very abundant, will, of course, decay much more
rapidly than poles that are in an absolutely sound condition.
The galleries of the chestnut timber worm afford an entrance to
1 the spores of wood-destroying fungi, and thus greatly accelerate
decay. White mycelium compactly filled these galleries throughout
many standing poles, thus clearly proving that these mines aid
greatly in enabling the fungous heart rot more rapidly and
completely to penetrate the entire heartwood of the poles. If tihe
injury by both wood-boring beetles and wood-destroying fungi
(between which there is a varying interrelation) be considered, then
in several lines from ten to twelve years old in North Carolina,
Virginia, and West Virginia at least 50 per cent of the poles are either
rendered unserviceable or their length of service is much shortened.
ASSOCIATED WOOD-BORING INSECTS.
It is not to be concluded that this wood-boring beetle is the only
insect that injures standing chestnut poles. Indeed, the most
common injury is by the "wood lice" or white ants. In lines from
ten to twelve years old these insects have seriously damaged as high
as 15 per cent of the poles, and their work is often present, at least
superficially, in as high as 75 per cent of the poles under all conditions
of site. However, the damage is usually to the outer layers of the
wood, where it is moist or there is incipient (lecay, and is more
superficial and localized than that of the chestnut telephone-pole
borer. Nevertheless, white ants often completely honeycomb the
sound heartwood of poles, especially at the base. They work both
in sound wood, "doty" (dry rot) wood, and "sobby" (wet rot) wood.
Sometimes a large channel runs up through the core of the heart
a Often this evidence is the old galleries of the destructive two-lined chestnut
borer (Agrilus bilineatus Web.), showing that the tree must have been dead before
it was cut for a pole, and hence is more likely to be defective throughout the interior;
in other instances heart rot is clearly present.
b Lymexylon sericeum Harr.
cIdentified by Mr. Theodore Pergande of this Bureau as TermnesfJlaripes Kollar.
INSECTS INJURIOUS TO FORESTS.
and the sides are plastered with clay, forming a hollow tube with
several longitudinal galleries. Their work often extends from 2 to 4
feet above tihe surface of the ground. They leave the outer shell
of thle wood intact and work up through the longitudinal weathering
checks, covering the exterior of the pole with earth to exclude the
light. White ants will damage poles that have been set in the ground
only two years. Evidently they enter the pole from below the surface
of the ground. The habits and characteristics of these peculiar and
interesting insects have been thoroughly discussed in Circular No. 50
of this Bureau by Mr. C. L. Marlatt.
A giant round-headed borera is sometimes found in the poles,
usually in association with the chestnut telephone-pole borer. In
poles where the wood is sound this borer apparently works as a rule
only in the outer layers of the wood, the galleries running longitudi-
nally through the heart below the surface of the ground. In poles
where there is decay it will completely honeycomb the heartwood
near the surface of the ground.
In several poles where the wood was "doty" a large Scarabeid b
which has before been found in decayed oak railroad ties was present
and caused the poles to break off sooner than they otherwise would.
The irregular galleries of the grub completely honeycomb the decayed
heartwood near or just below the surface.
A flat-headed borerc and wireworms d were found in galleries locally
in the more or less decayed heartwood of several poles. A large black
carpenter antc does some damage to sound poles set in dry ground
through woodland. This ant often widens the longitudinal weather-
ing checks and'thus accelerates decay. A small black ant1 was very
numerous in many poles, but its work is usually confined to the
outer layers of the wood. The work is often throughout "doty"
poles. Injury by this ant is not primary, but it also widens weather-
ing checks, enlarges other defects, and induces more rapid decay.
PREVENTION OF THE INJURY.
Doctor Hopkins makes the following statement in a recent bulletin:u
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 recom-
mended by the Forest Service for the prevention of decay. These should be applied
aPrion us sp.
b Identified by Mr. E. A. Schwarz, of this Bureau, as Polymncchus breripes Lee.
c Identified by Mr. H. E. Burke, of this Bureau, as Buprestis rufipes Oliv.
d Species of the family Elateridae. The large larvae of Alaus sp. were especially
e Identified by Mr. Theodore Pergande as Camponotus pennsylvanicus Mayr.
I Identified by Mr. Theodore Pergande as Cremastogaster lineolata Say.
g Insect Depredations in North American Forests.
DAMAGE TO CHESTNUT POLES BY INSECTS.
Before the material is utilized fur dthe purptes intended, or, if il II. ai Iacked afl-tr
it has been utilized, further damage can be checked to a cet-rtain exteint by the tise oif
the same substances.
I. It is often of prime importance to prevent injury from wood-boring insects, fir Ihe
l reason that such injuries contribute to more rapid decay. Therefore anliltiln Ihat
llwill prevent insect injury, either before or after the utilization of such jrhdi,'t-, will
contribute to the prevention of premature l deterioration and( decay.
:.Through the courtesy of the American Telephone and Telegraph
: Company and the Forest Service, about 40 chestnut poles set i a
test line near Dover, N. J., were inspected by the writer on July 15,
H 1910, in company with engineers of the telephone company adl Mr.
H. F. Weiss, Assistant Director, Forest Products Laboratory. IForest
Service, to determine the relative merits of various Inetlliod(s of pre-
venting damage by wood-boring insects to tlhe bases of 1)pole(s. In
: this line, which is eight years old, variously treated poles alternated
K. with untreated poles in order that each chemical preservative and
. method of treatment might be given an absolutely fair test unier
II the same conditions of site. Tihe poles were 30 feet long, 7 inclies
Sin diameter at the top, and 33 inches in circumference 6 feet from
| the base. In this inspection the earth was removed (to a depthh of
| ~ about 1 foot) from the base of the pole, and then the pole was chopped
* into to determine the rate of decay. This method of inspection for
insect damage is not very satisfactory. The various methods exp)eri-
mented with in this test line were brush treatments with a patented
carbolineum preservative and spirittine, charring the butt, setting
the pole in sand, and setting it in small broken stone. It was found
that, although these methods may temporarily check the inroads of
wood-boring insects, they will not keel) the insects out of thlie poles.
The most serious damage to the poles in this line was by white ants.
Other insect damage was by a large black carpenter ant a and the
larvae of a round-headed borer.b
An inspection was made, between September 6 and 14, 1910, of
the bases of over 400 chestnut poles set in a similar test line near
Warren, Pa., and Falconer, N. Y. These poles were treated by the
creosote "open-tank" method of impregnation, and brush treatments
of creosote, wood creosote, creolin, two different carbolineum pre-
servatives, and tar; they had been set in the ground for a period of
five years. All these treatments, except the brush treatments with
creolin and tar, were efficient in preventing the attacks of wood-
boring insects, at least for a five-year period, in this northern climate.
There was but little damage by insects to the poles in this test line.
The most common injury to the untreated poles was by the large
black carpenter ants which widen the longitudinal weathering checks,
and hence induce more rapid decay. The work of the chestnut tele-
a (Camponolus pen nsylh'anicus Mayr.
b Prionus sp.
INSECTS INJURIOUS TO FORESTS.
phone-pole borer was found in several poles, and this beetle was evi-
dently just beginning to attack these poles. There was some damage
by a rouind-headed borer.a No white ants or termites were present,
and this is evidently too far north for these destructive borers. A
report by inspectors of the American Telephone and Telegraph Corm-
plany and the Forest Service on the remainder of the poles in this
test line (between Jamestown and Buffalo, N. Y.) not personally
inspected by the writer, showed that these conclusions can be applied
to all the poles in the line with the exception that there was super-
ficial injury by small black ants to two poles treated by brush treat-
mnients of carbolineum avenarius and to two treated with wood creo-
sote; also, as the inspection progressed, injury by the chestnut tele-
phl)lone-l)ole borer became more abundant and serious, and the borers
seemed to be established in the poles. The poles treated by the creo-
sote "open-tank method of impregnation and by brush treatments
with creosote and with "S. P. F." carbolineum remained uninjured.
Methods of treating poles superficially by brushing with various
preservatives have proved to be temporarily efficient in keeping
wood-boring insects out, if the work is thoroughly done and not only
the butt, but also the base, is treated. If the pole is not thoroughly
brushed, insects enter through the untreated or imperfectly treated
portions, especially through weathering checks and knots. Where
the base is left untreated, insects, especially white ants or termites,
enter the pole from below ground and, avoiding the treated portions,
come right up through the pole.
The few poles of southern yellow pine in a line near Bartley, N. J.,
inspected on July 15, 1910, which had been impregnated with creo-
sote by the Bethell cylinder-pressure process, 12 pounds of oil to the
cubic foot, and had been set in the ground since February, 1903,
were apparently absolutely free from signs of decay or damage by
wood-boring insects. In another line, running between Norfolk, Va.,
and Washington, D. C., the few poles (12 years old, of squared-
with the sapwood cut away-southern yellow pine) inspected on
August 10, 1910, near Portsmouth, Va., which had been impregnated
with creosote by the Bethell cylinder-pressure process, were also
apparently absolutely sound.
Thus, it is evident that impregnating the poles with creosote by
some standard process (either the open-tank or the cylinder-pressure
processes) will keep wood-boring insects out and preserve the poles
for a much longer period than they would last untreated. In the
open-tank method onlt the area most subject to the attacks of wood-
boring insects and deterioration in general (i. e., the basal 8 feet) is
treated, while by the cylinder-pressure processes the entire pole is
impregnated. Alternating less susceptible juniper (red cedar)6 poles
" Priorus sp.
b Juniperus virginiana.
DAMAGE TO CHESTNUT POLES BY INSECTS.
or pine poles thoroughly in Lpregnatedl b son)ic stbiyiiid i pir,.., in
the line with the chestnut poles wouIld be a safeguard ill hlini'hhg 1p)
an old line where the damage is found to ie' s'rioiiu.s oil r1,(It tiIlitr
A list of some ava. ilable publirat1iolls o woo ;i jresIrv\iloll is
w r i n.3 .. ... e ....l.. 4
1907. -RWOD .G-h pntn ehdfrteteteto
< Cir.: ":1 Fo e" "er'ice .. S.ii ........r
12 INSECTS INJURIOUS TO FORESTS. 19 oetSri..
190S. ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ .....'.. "11. "E-rgesi hsntplepeevto.
1903. rON SCHRENK, H.-Seasoning of timber.
1906. GRINNELL, H.-Prolonging the life of telephone poles. lYewbq. t ..... ..
Dept. Agr. for 1905, Extract No. 395.
1907. CRAWFORD, C. G.-The open-tank method for the treatment of ti,
1907. GRINNELL, 11.-Seasoning of telephone and telegraph poles.
.. ... -' ,,u +
Service, U. S. Dept. Agr.
1908. SHERFESEE, WV. F.-A primer of wood preservation.
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U. S. Dept. Agr.
1908. WEiss, II. F.-Progress in chestnut pole preservation.
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1909. SHERFESEE, W. F.-Wood preservation in the United States.
1909. SHERFESEE and WEIsS.-Wood preservation.
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1909. KELLOGG, R. S.-The timber supply of the United States.
1910. WILLIS, C. P.-The preservative treatment of farm timbers.
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