Insect enemies of the pine in the Black Hills forest reserve

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Material Information

Title:
Insect enemies of the pine in the Black Hills forest reserve an account of results of special investigations, with recommendations for preventing losses
Series Title:
Bulletin / U.S. Department of Agriculture. Division of Entomology ;
Physical Description:
24 p., 7 leaves of plates : ill. ; 23 cm.
Language:
English
Creator:
Hopkins, A. D ( Andrew Delmar ), 1857-1948
Publisher:
U.S. Dept. of Agriculture, Division of Entomology
Place of Publication:
Washington, D.C
Publication Date:

Subjects

Subjects / Keywords:
Plant parasites -- Black Hills National Forest (S.D. and Wyo.)   ( lcsh )
Insect-plant relationships   ( lcsh )
Botany -- Black Hills National Forest (S.D. and Wyo.)   ( lcsh )
Pine -- Diseases and pests -- Black Hills National Forest (S.D. and Wyo.)   ( lcsh )
Genre:
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

Additional Physical Form:
Also available on the World Wide Web.
Statement of Responsibility:
prepared under the direction of the entomologist by A.D. Hopkins.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 029640728
oclc - 14644250
Classification:
ddc - 632
System ID:
AA00018939:00001

Full Text


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A... S DEPARTMENT OF AGRICULTURE
>5,I:-ISION OF ENTOMOLOGY-BBULLE1 IN NO. 32, NEW SERIES.'
Z. .' L. 0. HOWARD, Entomologist.

t HILLS.'-. -,
4~



.ENEMIES OF THE PINE IN-THE BL

-T.
*'HILLS FO REST'nRESRVE,^







STS SPECIAL INVESTIGATIONS, WITH

;^tfRECOMMENDATIONS FOR PREVENTING LOSSES.
a,... S "-











OFADERTHE DIRECTION OT THE ENTOMOLOGIST


ByA. b. HO-PKINS, Ph. D,

0 n d En.om"ologist of the West Virginia Agricultural
', cp'c"..E priment c-"






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U. S. DEPARTMENT OF AGRICULTURE,
DIVISION OF ENTOMOLOGY-BULLE1 IN NO. ;32, NEW SERIES.
L. 0. HOWARD, Entomologist.




IIISECT ENEMIES OF THlE PINE IN TIlE BLACK

HILLS FOREST RESERVE.




AN ACCOUNT OF RESULTS OF SPECIAL INVESTIGATIONS, WITH
RECOMMENDATIONS FOR PREVENTING LOSSES.




PREPARED UNDER THE DIRECTION OF THE ENTOMOLOGIST.

By A. D. HOPKINS, Ph. D.,


Vice-Director and Enonlulogist of the West Vi,'iji, ia. Agricudtii. rald
Exp<:,'it-,,t Station.


WASHINGTON:
GOVERNMENT PRINTING OFFICE,


1902.
















LETTER OF TRANSMITTAL.


U. S. DEPARTMENT OF AGRICULTURE,
DIVISION OF ENTOMOLOGY,
Tashington, D q, January 22 1902.
SIR: In the temporary absence of Dr. L. 0. Howard, Chief of the
Division of Entomology, I have the honor to transmit herewith the
manuscript of a paper entitled "Insect Enemies of the Pine in the Black
Hills Forest Reserve," by Dr. A. D. Hopkins, Entomologist of the
West Virginia Agricultural Experiment Station. The extensive losses
occasioned in recent years by insects to forest lands in various portions
of the United States, and particularly in the North and Northwestern
regions, have attracted great attention, and have necessitated investi-
gations as to the character of the injury in order that the most appro-
priate methods of control may be advised. The present contribution
is the third of a series bearing upon the insect enemies of coniferous
trees, and comprises a summarized account of results of a special
investigation that was made during the year 1901 under instructions
from this Division and with the cooperation of Mr. Gifford Pinchot,
Forester of this Department, together with a consideration of valuable
suggestions for preventing losses, based upon studies by Dr. Hdpkins
extending over a number of years. I recommend its early publication
as Bulletin No. 32, new series, of this Division.
Respectfully,
F. H. CHITTENDEN,
Acting Ei tomolog ist.
Hon. JAMES WILSON.,
Sec,,tary <0f lf/rieulttUe.



















CONTENTS.



Page.
Request, authorization, and instructions----------------------------------.................................... 7
The investigating trip------------.....-----.......---.-----.......-----....------------------ 7
The conditions observed- ..-------.......---...---------------..............-----...---------------. 7
The amount of dead timber -------------------------------------------- 7
Historical references..........--------------------------..........--------..--...--------------... 7
The trouble caused by insects --------------------------------- 9-----------
The primary enemy ------------------ --------------------------------9
Name of the beetle --------.-----.-------........---.-------------..-----------. 9
Secondary enemies .--------------.....-----.......--..-------------.....-----..-----------........ 10
The Oregon Tomicus (Tomicus oregoni Eichh.) ......................... -------------------------10
The coarse-writing bark-beetle (Tinici,. calli;tji'aphui.- Germ.)------------ ............ -11
The wood-engraving Tomicus (To;in'ri.s cxlatus Eichh. var. .r.qpiinrum,
n. var.)..--.------------------------------------------------------- 12
The dark-red turpentine beetle (Dendroctowi.,v w'o,.s. Lee.)..-------......---..------ 12
The western pine Hylurgops (-17liitgjip.s subcostulatus Mann.) ...-..---.------. 13
The pine-root bark-beetle (Hu-ai.i;. p<,,,._. Er.)------------------------ ........................ 13
Branch and twig beetles------------------------------------------ .............................................. 14
Ambrosia or timber beetles and wood-boring grubs ---------------------14
Small trees dying from other causes -.........------------.......-----....---------..--------. 14
The rock pine pitch-worm------------------------ ............................-..-----..------------. 14
The pine weevil ------------........-..----------...--------.....-----.....--------------14.
Insect enemies of the foliage .------------------.........-----............-----....-------------- 15
Natural enemies of the destructive and injurious inseet.-'--------------------.................... --15
Predaceous enemies------------------------------------------ .................................................. 15
The 1 iluish-green preldaceous beetle------------------------------ ................................ 15
Clerid beetles andl their larve ..................................... -----------------------------------15
Red-bug enemy of the bark-beetle (T,'oeo.;te, P ,,'.,'//,. Fab.)...------.. 16
Other prelacei-us beetles-------------..................---...------.....-----------------...... 16
Parasitic insects ----------------------------------...................................................... 16
Parasitic fungi------------------------------------------------------........................................................ 16
Birds as enemies of the destructive beetle .............................. -----------------------------16
How the trees are attackeil and killed----------------------------------- ..................................... 17
Characteristic features of the living, dying, and dead trees infested and killed
by the beetle-----------------------------------------------------........................................................... 19
Borings and pitch tubes------------------------------------------ .............................................. 19
Appearance of the leaves..............................................------------------------------------------ 19
Appearance of the trees that have been dead three years or more--------....... 19
Evidence of the work of the beetle on old dead trees.................... 20
The relation of wood-boring insects and wood-destroying fungi to the rapid
deterioration of the wood--------------------------------------------................................................ 20
3






CONTENTS.


Suggestions for preventing losses ---.------.....----.------....--------------------.............. 20
Metthods of combating the enemy and preventing losses from its ravages.
To reduce the numbers ............---------------------.----.-------...............--.------ 21
Suggestions for preventing further trouble----..---------------------............ 22
To prevent losses from wood-boring insects----- .........------------------. 22
The protection of living timber...................................---------------------------------. 22
Evidences of unnecessary cutting of living timber. ------..--------------------................. 23
Suggestion, concerning timber-cutting contracts---------------------------............................ 23
Need of further investigation----------...--------------------------------...................... 24
Cutting andl barking the infested trees in winter-----------------------....................... 24
The experiments of girdling, cutting, and treating trees-...---.........-..... 24

















ILLUSTRATIONS.



PLATES.
Pato.
PLATE I. Work of the pine-destroying beetle of the Black Hills ............. 8
II. Work of the coarse-writing bark 1 leetle--------------------------- ........................... 8
III. Work of the pine-destroyinsr beetle of the Black Hills. Fig. 1.-
Primary galleries and larval mines in inner 1 iark. Fig. 2.-M-arks
of primary galleries on surface of scoring chip -..-----.....------------....... 12
IV. Work of the pine-destroying beetle of the Black Hills. Fig. 1.-
A, Primary galleries, larval mines, pupa cases, and exit holes;
B, Primary galleries grooved in .-urface of wood in chip cut from
railroad tie. Fig. 2.-Evidence of cutting living trees. A, Scor-
ing chip from railroad tie, showing surface of wood not marked
by insects; B, showingg inner surface of bark from same chip.... 12
V. Work of the Oregon Tomicus. Fig. 1.-A, Galleries engraved in
surface of wood cut from old dead tree; B, Bark with inner
portion destroyed by galleries and larval mines. Fig. 2.-Gal-
leries in inner bark and surface of wood of railroad ties and edg-
ing strips----------------------------------------------- .................................................... 16
VI. Work of the rock-pine wood-engraver (Piyg, ws car-iiuc.p. Lee.).
Galleries in inner biark and surface of wood-------------------- .................... 16
VII. Scenes in the pine forests of the Black Hills Forest Reserve-work
of Dcndrocl,' i,. poudh''r,., Hopk. Fig. 1.-Stmiall freshly attacked
pine tree, showing pitch tubes. Fig. 2.-Marks of primary gal-
leries on the surface of wood when bark is removed. Fig.
3.-Freshly attacked tree, showing pitch tubes; adjoining tree
not attacked. Fig. 4.-Dead tree, outer bark removed by
woodpeckers---------------------------------------------................................................. 20

TEXT FIGURES.
Fio. 1. Work of the pine-destroying beetle of the Black Hills..----------- 9
2. Work of the Oregon TomicJus-----------------------------------...................................... 10
3. Work of the Oregon Tomicus.-----------------------------------..................................... 11
4. Work of the Oregon Tomicus-----------------------------------...................................... 12
5. Work of the rock-pine wood-engraver.............................. 13















INSECT ENEMIES OF THE PINE IN THE BLACK HILLS
FOREST RESERVE.

REQUEST, AUTHORIZATION, AND INSTRUCTIONS.
The work herein reported was undertaken by request of Mr. Gifford
Pinchot, Chief of the Bureau of Forestry, under authorization from
the honorable Secretary of Agriculture and instructions from Dr. L. 0.
Howai'd, Chief of the Division of Entomology.
THE INVESTIGATING TRIP.
The investigations were conducted, in company with Mr. Pinchot
and his chief field assistant, Mr. Griffith. on September 1 to 4, 19)01,
along a route traversed through the reserve from Spearfish, via Iron
Creek, Bear Gulch, and Cement Ridge, South Dakota, Rifle Pit,
Wyoming, and Spearfish Creek, to Lead, S. Dak.
THE CONDITIONS OBSERVED.
Vast numbers of rock pine (P/uY ,pndcri ',,.vjmilorum) that were
dying, or had died within recent years, of sizes ranging in diameter
From 4 inches to the largest trees, were observed along the route.
The dying trees occur in clumps of from a few examples to many
hundreds, and in some sections, as viewed from the summit of Cement
Ridge and other favorable points, the dying, recently dead, and old
dead trees cover large areas.
THE AMOUNT OF DEAD TIMBER.
Mr. H. S. Gravesa estimated in 1897 that about 3,000 acrel, of pine
in the Black Hills Forest Reserve had been killed. Further data fur-
nished by the Bureau of Forestry show that the actual amount of dead
timber, as determined by Mr. Griffith and party in a detailed survey of
the timber resources of the reserve in 1901, is. "An average stand of
1,956 feet board measure of bug-killed timber on 116,000 acrcs. giving
a total of 226,,s00,00 feet board mea-ure."
HISTORICAL REFERENCES.
It is the general opinion among settlers and others who have had an
opportunity to note the conditions affecting the pine that the dying
timber commenced to attract attention about six or sevei years ago,
or about 1895.
Nineteenth Aninual Report U. S. ideological Slurvev, 1S97-9S, P'art V, p. 87.








The evidence found b)y the writer in old dead standing and felled
trees indicates that the pine-destroying beetle has been present. for a
much longer time. It was also evident that much of the devastation
supposed to have been caused by forest fires was caused, primarily, by
in.-!ects.
Mr. Graves, in his exhaustive report on the Black Hills Forest
Reserve, refers, on page 87, to insects and the dead pine timber as
follows:
On the high limestone divide, from near Crook Tower to the head of Little Spear-
fish Creek, there are numerous patches of dead and dying timber. These patches
are usually rectangular in shape and follow the tops of the divide and ridges, or run
lengthwise up and down the slope. This forest has for the most part not been lately
burned, and there is a heavy matting of litter and humus on the ground. The injury
is confined to the limestone formation and to high elevations. The trees are in many
cases second growth and apparently perfectly thrifty. This injury is probably
caused by insects. On all (lead and dying trees examined were found bark borers, a
species of the Scolytidae, working under the bark. In most cases the leaves were
clinging to trees which had been dead for several seasons. While these borers do not,
as a rule, attack vigorous trees, no other cause of the death of this timber could be
found.
Mr. H. E. Dewey, writing to the Division of Entomology from Lead,
S. Dak., on August 12, 1899, stated:
* There have been none in the trees this year until last Wednesday, the
9th. On that day there was a southwest wind, and a swarm of them came. Mv
dwelling is in what was a grove of young native Black Hills pines. The bugs settled
on the house like a plague of locusts. At night they left the house and scattered
about. I have examined the trees, and with one exception do not find that they
attacked them. This one excepted tree is a sight. Hundreds of bugs settled on it
during the night, and by morning they had buried themselves out of sight in the
trunk. As they bored their way in, the dust from their boring, which was very
fine, filtered out from the top to the bottom of the tree like fine sawdust, and fell-
about the tree on the ground. They could be plainly heard at their work as they
bored into the wood. The tree was a vigorous young pine about 15 feet high and 6
inches in diameterr at the ground, and there is no apparent reason why they should
select it more than others. Last year they were here in June.

The following copy of a letter addressed to the Department of the
Interior, Division of Forestry, was submitted to the author from the
Division of Entomology, with a specimen of the insect, which, together
with the specimens sent with Mr. Dewey's letter, formed the material
from which the species was named and descriptive notes were made.
The letter is dated Piedmont, S. Dak., August 14, 1S98, and reads as
follows:
Many of the pine trees in this vicinity are dying. Small holes appear in the bark,
a reddish pitch exudes, the leaves turn brown, and in a few weeks the tree dies. I
think the mischief is done by the small black insect inclosed herewith, which I found
in one of the hole s. Is there anv remedy?

Nineteenth Annual Report U. S. Geological Survey, 1897-98, PartV, pp. 67-164.

.J


..iij










Bul. 32, New Series, Div. of Entomology, U. S. Dept. of Agriculture.


WORK OF THE PINE-DESTROYING BEETLE OF THE BLACK HILLS (DENDROCTONUS
PONDEROSA N. SP.). PRIMARY GALLERIES AND LARVAL MINES IN INNER SUR-
FACE OF LIVING BARK.
a, Entranic and basal chamber: b, .viitil.itiii_, holes in roof of gallery; c. termination.
T1i, larval mines radiate from the priimry galleries. About one-half natural size.
(Origimal.)


PLATE I.

















































































II


- "....... . . .......... . . . . .. .. . . .. ..









Bul. 32, New Seies, Div. of Entomology, U. S. Dept. of Agriculture.


WORK OF THE COARSE-WRITING TOMiCUS, IN INNER SURFACE OF BARK FROM
DYING PINE.
a, Entrance: b, central chamber; c, primary or ,. galleries. Reduced about one-half.
(Original.)


PLArE II.










9

THE TROUBLE CAUSED BY INSECTS.
The evidence obtained from a study of all stages of the afflicted tim-
ber. including the living, dying, recently dead, and old dead trees, of
all sizes, and under widely varying conditions of altitude, exposure,
geological formation, soil, and character of growth, indicates quite
clearly that this widespread, unhealthy, dying, and dead condition of
the timber is the work of insects.
THE PRIMARY ENEMY.
The evidence found also clearly indicates that the insect which makes
the first attack on the living trees, and therefore the primary cause of
the trouble, is a small, black, bark-boring beetle, belonging to a species
heretofore unknown to science, and appears to be peculiar to the Black
Hills region.a
NAME OF THE BEETLE.
Since this primary enemy lihas not been distinguished from a number
of other bark beetles found in the infested trees, it has not been desig-


r\ ^-/ ^ v\ Y v- -^ (,_ ./ ~ _
FIG. 1.-Work of the pine-destroying beeilt ,>f the Blark Hill-. ii inner bark of dvad tree. a, pri-
marygalleries: b, larve mines: purel chlnambers: d. exit hdli:.,. uL.dueed iiblout one-half i original I.
nated by a local name. I would therefore suggest that hereafter it be
designated as "6the pine-de -troying beetle of the Black Hills," and by
a Since this was written it has been reported from Colorado.-A. D. H.






10


the technical or Latin name Dendroctonus ponderosa.a The adult is a
stout, dark-brown to black beetle, individuals of which vary in length
from 4 to 7 mm. (about one-sixth to one-fourth inch). They attack
living and healthy large and small pine trees, enter the bark on the
main trunk, and each pair excavates a long, nearly straight, longitudi-
nal gallery through the inner bark (Pl. 1 and fig. 1), usually grooving
the surface of the wood. Eggs are deposited along the sides of this
primary gallery and hatch into minute white grubs (larvae), which
excavate mines through the bark at right angles to the primary gallery
(fig. 1, b). These mines are extended and enlarged as the larvte
increase in size, and when
full grown each individual
) r i excavates a broad, oval
c cavity in the bark (fig. 1,
:^ V c), in which it transforms
c Nato a soft, white pupa, and
then to the adult, which
bores out through the bark
(fig. 1, d), and flies, with
(other adults of the same
If-" .- .=. and other broods, in search
l N of other living trees in
":t\ which to excavate galleries
and deposit eggs for an-
== other brood.
SECONDARY ENEMIES.
AMany other species of
bark beetles and other
FIG. 2.-Work of the Oregon Tomicus (Tuin cts oregoni Eichh.). ark and wood infesting
Primary galleries anid larval mines in inner bark. a, Eu- insects were found asso-
trance; b, central chamber excavated through inner bark; cited with the primary
c, egg galleries; d, location of central chamber not exca- p
vated through inner bark. Reduced about one-half (origi- enemy in the partly living
,,l ). bark of infested and dying
trees, but none of them were found making an independent attack on
living trees. Therefore they must be considered as secondary ene-
mies, which follow the leader in the attack, and merely contribute to
the rapid and certain death of the trees thus infested.
The Oreyon Thwicus (Tomeutts oreqoni Eichh.).-This is a small red-
dish to black bark beetle, individuals of which vary in length from
3.II mm. to 4 mm. It follows closely the attack of the pine-destroying
beetle, and enters the bark on the large and medium sized branches
and toward the top of the main stem. Several females excavate radi-
"This species ha, heretofore been erroneously identified as D. terebrans and D.
ruitfipennis, and will probably be found so labeled in some collections.








ating galleries from a single entrance and a central chamber (fig. 2, a
and b). The central chamber may (a), or may not (b), extend through
the inner layers of bark and groove the surface of the wood, but the
radiating galleries are nearly always grooved in the surface of the
wood, as are also the egg cavities, which are excavated at short inter-
vals along the sides (figs. 3 and 4). These grooved and notched carv-
ings are often very conspicuous in the surface of the wood of trees
and logs for many years after the bark is removed or has fallen away.
The number of galleries branching from the central chamber varies
from two to five or
six, but the normal
number is four-two
above and two below
the entrance. The
mode of development
of the young stages is
the same as in the pre-
ceding species. (See
P1. V.)
This is a common A
enemy of the rock pine /
(Pinus ponderosa sco-
pulorum) throughout
the Rocky Mountain f
region and ot P. pon-
derosa west of the
mountains. It is ever
ready to attack and
prevent the recovery
of trees of all sizes / f
which are suffering
from weakened vital-
ity. It is also at-
tracted to recently FIG.3.-WorkoftheOregon Tomicus. Primary .allerit.c cngraivcl
felled trees, and breeds i riinrfai.-e of wood. Central chamber not extendimL-,.i into wood
e esec except at a. Reduced about one-half (urigiin).
in enormous numbers
in the bark on the tops and branches. The species was found to be
exceedingly common in trees infested by the pine destroyer and on the
logs and tops of those felled by the lumbermen.
The coa'rse-writing bark-betle (Tow- r..' i calif/rap )Is Germi. var. o(?'-
dentalis).-This is much larger than the Oregon Tomicus, but is of the
same color and general form. Individuals vary in length from 4.5 mm.
to 6.5 mm. This species also follows closely the first attack by the
pine destroyer. It enters the bark from near the base to toward the






12


top of the tree, and excavates three or four long longitudinal galleries
from a single entrance and broad central chamber (Pl. II). The cen-
tral chambers and galleries are usually grooved in the surface of the
wood, but can be readily distinguished from those made by the Oregon
Tomicus. It is a common and widely distributed species over the
greater part of the pine-producing areas of the United States from
the Atlantic coast to and including the Rocky Mountain region.a It
attacks all of the Eastern and Southern pines, and doubtless several
of the Western pines in addition to the rock pine, in which it was
found in large numbers
/ 9 in the Black Hills region.
/ The wood-engraving
Ton icu s (Tomicqus cola-
i/ tus Eichh.).-This is a
\much smaller and more
slender bark beetle than
the two preceding spe-
cies. Individuals vary
l in length from 2.6 mm.
to 3.2 mm., and in color
from dark red to dull
/ / black. This is also a
/ common, widely distrib-
juted, and variable spe-
S\ cies. It extends from
\ the Atlantic to the Pa-
cific, and infests all of
the Eastern and South-
Sern pines and spruces. AX
1 oe r n. var.) was found in the
r rock pine of the Black
FIc.. 4.-Work of the Oregon Tomicus. Primary galleries en- Hills, and has been col-
graved in surface of wood. Central chamber extending into elected by the writer from
wood. Reduced about one-half (original). a number of other spe-
a number of other spe-
cies of Western pines. It attacks and breeds in the inner bark on the
roots, trunks, and branches of weakened and dying standing trees of
all ages and sizes, from the very young to the oldest and largest. It
also breeds in immense numbers in the stumps, logs, and tops of
recently felled trees.
T/e dark-red turpentine beetle (Dendroctonus valenis Lee.)-This is the
largest of the known North American bark beetles. The adults vary
in length from 6 mm. to 9.5 mm. It attacks the bark on the base of liv-
"The Western form seems to be sufficiently different in some minor characters to
warrant this distinction in variety name-occidentalis.















































FIG. 1.-PRIMARY GALLERIES AND LARVAL MINES IN INNER BARK.


FIG. 2.-MARKS OF PRIMARY GALLERIES ON SURFACE OF SCORING
























































FIG. 1.-A, PRIMARY
AND EXIT HOLES;
FACE OF WOOD IN


GALLERIES, LARVAL MINES, PUPA CASES,
B, PRIMARY GALLERIES GROOVED IN SUR-
CHIP CUT FROM RAILROAD TIE. (ORIGI-


FIG. 2.-EVIDENCE OF CUTTING OF LIVING TREES. A, SCORING CHIP FROM
RAILROAD TIE, SHOWING SURFACE OF WOOD NOT MARKED BY INSECTS;
B, INNER SURFACE OF BARK FROM- SAME CHIP. ABOUT ONE-THIRD


I



































..








ing and dying standing trees and the stumnps of felled ones, and ex(-a-
vates a broad, crooked, longitudinal gallery. The eggs are deposited
in masses along one side, and when they hatch the hlar\a work together
and excavate a broad chamber, instead of making individual laiwrval bur-
rows, as is the rule with most other species. One of the striking pecul-
iarities of this insect is the habit of the adult and larva of living in
the quantity of semiliquid pitch or turpentine which acciiinulatc., in
the primary gallery and brood chamber. While this beetle is ca;ipablde
of attacking and developing its broods in the bark of a living, healthy
tree, it seldom causes the death of trees unaided by other insects. It
does, however, contribute to
the death of trees attacked by 6/9'.C .' ?i' /
the piine-destroying and other \ A .'.
destructive beetles. It is a 1 C 6,1N
common insect in the Rocky _
Mountain region and west to .
the Cascades. A variety (Den-
(Uoc'toa w^ rip9ens orhu:ntalis) is ) f/ )
(Irocto::::=^Sl I/> '(W S) is I^'' '
common in the East, attacking ,,. .-
'2
in the same manner all of the '! "3 .'-
Eastern pines. \
The llc'6trn _pine ]fIyll/r- w' 1i//,,1
VI Mann.).-This is a common, ---,.
dull brown to black bark beetle, /
ranging in length from 3.5 mm. &' ^
to 4.5 mm., which attacks and I ., ,'
breeds in the bark on the roots / I
and bases of dying trees and the '// j ..
stumps and logs of felled ones. / . .,^
It excavates a single longitudi- i'' .. f
i f AS}\ l'\ '' *
nal gallery, and the broods de- ( ''.
velop in confused or irregular i A'
larval mines in the inner 1bark,
larval mines in the inner bark, FrIG. 5.-Work of the rock pine wood engraver (Pi-
but rarely groove the surface / ,,1,.j c0n1iiips Lee.). Primary gilltriv. and
of the wood. This is one of larval mines in inner bark and :.iriit.a' of wood.
Reduced about one half (0 ,rigiil).
the commonest bark beetles
from the Rocky Mountain region to the Pacific coast, and will evi-
dently he found wherever the rock pine or Western yellow pine grows.
The pine-root bark-b.cfle (Ify,._t-. poro.its Lec.).-This is a blahtck,
elongate, slender bark beetle, varying in length from 4 mm. to 5 mm.
It attacks the bark on the roots of the Western pine and excavates a
single longitudinal gallery from which the brood burrows radiate,
and the broods develop in the usual manner. It was found in the
bark on the roots of young seedling pines which had recently died,






14


and also in the bark on the roots of the stump of a recently felled
tree in the Black Hills. This is also a common species of the Rocky
Mountain pine regions.
Branch and twig beetles.-The large and small branches and termi-
nal twigs of the trees that were dying from the attack of the pine-
destroying beetle were found to be infested by a number of described
and undescribed species of the genus Pityophthorus and by Pityogenes
cariniceps, all of which attack the bark as soon as the trees commence
to die, and contribute, more or less, to hastening the death of the trees.
Ambrosia or timber beetles and wood-boring grubs.-The wood of the
trees was found to be infested by the Western hemlock wood stainer
(Gnatlhotrichus sulcatus Lee.), the Western pine wood stainer (Onatho-
trichus occidentalis Hopk. MS.), and several unidentified Buprestid
and Cerambycid larvae, which attack the trees, and when they com-
mence to die bore into the sapwood and contribute to its rapid decay
by giving entrance through their burrows to wood-decaying fungi.
SMALL TREES DYING FROM OTHER CAUSES.
The rock-pine pitch worm.-In addition to the trees killed by the
pine-destroying beetle, quite a number of young pines 2 and 3 inches
in diameter were found in the vicinity of Spearfish and Crow Peak
that were seriously injured by the larva of an undetermined Sesiid
moth working in the living bark of the main stem and causing ugly
wounds. Successive attacks on the same tree weaken its vitality and
attract the Oregon Tomicus and species of Pityogenes and Pityophtho-
rus, which infest the main stem and branches, while a number of the
root-infe.ting bark beetles and a pine weevil attack the base and roots,
and the tree soon dies. Only a dead and dry larva and a dead chrysa-
lis of this insect were found. The characters exhibited by these speci-
mens do not agree with the descriptions of the larva of the sequoia
and pine-destroying Sesiid (Bembecia seq uoia= Vespamima sequoize Hy.
Edw.") or of the larva and chrysalis of the pine Sesiid (Ifarmonia
2/i- Pa/rharmono1a pinl Kellicott b).
The destructive habits of this class of enemies of trees (which
includes the common peach-tree borer) suggest that this may be a
common and destructive enemy of "- reproduction" pines in the Black
Hills and other pine-producing areas of the West.
The pine weevil.-In another section near the Wyoming and South
Dakota lines many young trees were observed which were apparently
d(lying from the attack of a pine weevil (Pissodes sp.), or the combined
attacks of this insect, a root fungus disease, and a number of species
of bark beetles.
"Mem. Am. Mus. Nat. Hist., vol. 1, part vi, Mongr. Sesiide. Am. North of Mex.
1901, p. 263, with bib. ref.
bIbid., p. 264.








INSECT ENEMIES OF THE FOLIAGE.

Little time was had to collect or study the enemies of the foliage,
but from general observations there was no perceptible injury from
this class of depredators.

NATURAL ENEMIES OF THE DESTRUCTIVE AND INJURIOUS
INSECTS.

Numerous species of p)redaceous and parasitic insects were found
associated with the primary and secondary enemies. Some evidence
was found of the beneficial work of birds, and a few examples of the
pine-destroying beetle were found that had been killed by a disease,
but in no case was there sufficient evidence to indicate that any of
these natural enemies, or all combined, were in sufficient numbers to
render any special service toward bringing the trouble to an end.
They were undoubtedly rendering some service, however, in prevent-
ing the rapid multiplication of the pine destroyer, which would other-
wise occur.
PREDACEOUS ENEMIES.

The 6hweh--/c'n ,eade dcous wijcfb, (Lo7qo.gita ';,',. w,/s Fab.).-Thi- is
an elongate, flattened, shining, green beetle, varying in length from
10 mm. to 13 mm., and in width from 3 mm. to 4 mm. The larva
is a long, slender, reddish to whitish worm, with shining black head
and prothoracic plates. This recognized predatory enemy of bark-
infesting insects was frequently found associated with colonies of the
pine-destroying beetle and the secondary enemies, and a few adults
were found hiding beneath the flakes of outer bark. This widely dis-
tributed insect in North America has not been sufficiently studiedd to
determine its true relation to the destructive enemies of the. trees, blut
it is evidently quite beneficial.
Clerid termined species of this class of predaceous enemies of bark beetles
were found in small numbers in the bark with the broods of the
destructive and other species of bark beetles. This class of beneficial
insects usually renders great service in reducing the numbers of the
destructive and injurious species. Therefore their scarcity in this
region may have had much to do with the rapid multiplication and
spread of the pine-destroying Dendroctonus. While collecting spec'i-
mens of bark beetles from saw logs in a mill yard at Boulder, Colo.,
on August 25, one of the-e Clerids (Cl 10 ., n./,/uLec.) was very
common. The active, ant-like adults, which are black, marked with
transverse patches of gray, vary in length from 6 mm. to 8 mm., and in
width from 2.5 mm. to 3 mm. The larva is a slender, pale red worm.
The adult feeds on and destroys great numbers of the adult bark








beetles before they enter the bark and when they emerge, while the
larva destroys the larva and broods in the bark.
A r'd-bnug enemy ous bug of the family Acanthiidae and subfamily Anthocorina was
found in all stages of development, associated with colonies of the pine-
destroying beetle and its allies, in the bark of recently attacked living
and dying trees. These little relatives of the bedbug and the flower
bugs are recognized as aggressive enemies of bark beetles, both in the
East and West. The one found in the Black Hills is evidently Pizos-
tet/its californicus Rent. The adult is about 3 mm. long, slender,
grayish, and exceedingly active. The young forms are usually bright
red, active little creatures which attack and suck out the liquids from
the bark beetles and their larva. The adult bug also attacks and
kills the adult bark beetles. VWhile this is a common and active enemy
of the smaller bark beetle, it probably does not render much service
toward checking the ravages of the destructive species.
Other pr)edaceous betles.-There are also a number of predaceous
beetles of the families Colydiidin, Tenebrionidie, Histeride, and
Staphylinidc which were found in greater or less numbers in the
bark of infested trees, but their exact relation to the destructive
beetle was not determined.
PARASITIC INSECTS.
Several parasites belonging to the order Hymenoptera and families
Braconidie, ChalcididT, and ProctotrupideN were found to be enemies of
the smaller bark beetle larviae and adults, but none were found attack-
ing the pine-destroying species. Therefore there does not seem to be
much service rendered by this class of insects, which are usually so
efficient in reducing the numbers of bark beetles.
PARASITIC FUNGI.
A few examples of the adults and larvae of the pine-destroying beetle
were found which had evidently been killed by a fungus disease, but
this was by no means common enough to have rendered any service
in checking its ravages.
BIRDS AS ENEMIES OF THE DESTRUCTIVE BEETLE.
A few old dead trees and some which had been recently infested
which showed evidence of the beneficial work of woodpeckers were
observed in some localities, but hundreds of other insect-killed trees
showed no trace of work by the birds. Therefore there appears to be
very little service rendered from this source. This is evidently due
to a scarcity of the birds and to the fact that the habit of the insect
transforming to the adult in the inner bark makes it less accessible to
the birds than are the spruce-destroying beetle and other bark beetles
which undergo this change in the outer bark.


"a, n~











a-
4-L


















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-.-

















co
o-GL E-
DSS









NAL.
in ")
-U), :J ,
"a...) .
z
(N'



FI.1-,GLEISEGAVDI UFC FWO UTFO L I.2-ALRISI NE AKADSRFC FWO FRIRA
DEDTE;BBRoIT NE OTO ESRYDB ALR TIE AN EDNGSRP.AOT N-HID AUAL IE. ORI
IE N AVl.MNS BUTO TII NTRLSZ.'OII A.
NAL'


------ ... . ................
















































































































































d









Bul. 32, New Series, Div. of Entomology, U. S. Dept. of Ancu'tur.


WORK OF THE ROCK PINE-WOOD ENGRAVER (PITYOGENES CARINICEPS LEC.). GALLERIES
IN INNER BARK AND SURFACE OF WOOD. ABOUT ONE-THIRD NATURAL SIZE. (ORIGI-
NAL.)


PLATE Vl.
































































































































a









Bul. 32, New Series, Div. of Entomology, U. S. Dept. of A,;c,'tur-.P


WORK OF THE ROCK PINE-WOOD ENGRAVER (PITYOGENES CARINICEPS LEC.). GALLERIES
IN INNER BARK AND SURFACE OF WOOD. ABOUT ONE-THIRD NATURAL SIZE. (ORIG:-
NAL.)


PLATE Vl.











HOW THE TREES ARE ATTACKED AND KILLED.
Many hundreds of trees were examined during the investigation,
including those that were living and perfectly healthy, living and
freshly attacked, infested and dying, recently dead, and old dead ones
which bore evidence of having been killed by the pine-destroying
beetle. All stage.. of the insect, including the adult, the egg, different
stages of the larva, the pupa, and recently transformed beetles, were
observed and studied, as were also all stages of the primary entrance,
the gallery and brood mines- in the living, dyingo, and dead b]ark, and
also the primary gallery grooves on the surface of the wood of old
dead trees and logs from which the bark had fallen and decayed.
The evidences gathered from these studies, and from information
conveyed in Mr. Dewey's letter, quoted on another page, indicate that
the principal attack is made in August, when it would seem the beetles
migrate in swarms from the dying trees. and settle on the living ones,
which they attack and infest in large numbers from near the base to
the upper part of the main trunk or stem.
The trees that are attacked by a sufficient number of the beetles to
overcome the resistance exerted by the vital forces of the plant com-
mence to decline, and by winter or the following spring they die and
the leaves turn yellow and red. Those not attacked by sufficient num-
bers of the beetles to overcome this vital resistance recover and are
usually exempt from future attacks; the wound., heal and are covered
over by subsequent layers of wood, thus causing pitch spots or gum-
streak -defects in the wood.
The details of the work of the attacking force of beetles on a living
tree may be briefly described as follows:
Both sexes settle on their victim, usually in large numbers, and the
males (?)a commence to excavate the entrance burrows, which are usu-
ally hidden in a crevice or beneath a flake of the outer bark. The
reddish, sawdust-like borings thus produced and thrown out fall to the
ground around the base and lodge in the loose outer bark on the trunk.
When they enter the inner living bark, or bast, the tree commences
to exert its resistance by throwing out pitch to fill and heal the fresh
wounds in the living tissue. Then the struggle between the resisting
force of the plant and the beetles begins in earnest. Each femiale
joins her mate. and together they continue the excavation. The bor-
ings and pitch are disposed of by being pushed out and formed into
a pitch tube at the mouth of the entrance burrow (Pl. VII, figs. 1, 3,
and 4). The inner bark is entered obliquely and subtransverscly to
the cambium and surface of the wood, where a broadened cavity is
excavated for the accommodation and temporary occupation of the
aWhile it was not positively determined that the male of this species excavates
the first entrance, it is the habit of many other bark beetles, and is probably followed
by this.
16274-No. 32-02-- 2






18


pair, l)robably until the principal flow of pitch is exhausted. The
gallery is then extended (probably by the female) transversely or sub-
transversely for a short distance (seldom more than an inch), and then
longitudinally up or down the tree, but usually up, varying from a
few inches to a foot and a half, the normal length being about 1 foot.
As soon as the gallery has been extended 1 or 2 inches from the
entrance and basal cavity, small notches, or cavities, are excavated in
the sides of the gallery, in each of which an egg is deposited, and so
on until the gallery is completed. As the eggs are deposited, the bor-
in'gs, instead of being thrown out at the entrance, are closely packed
in the entrance burrow, basal cavity, and gallery, except near the
farther end, which is kept open, enlarged, or extended to one side or
the other, as it is occupied by the parent beetles, after their work of
constructing the egg gallery is completed, until they die (P1. I).
The bark of an infested tree is usually occupied by one of these
primary galleries in every 1 to 6 inches of circumference from near the
base to near the middle of the trunk (Pl. VII, fig. 2). Therefore they
effectually check the normal movements of the sap, and the larval
mines, which radiate from the primary gallery, destroy the intervening
bark and complete the girdling process.
Ten or twenty, or even forty or fifty pairs of beetles, attacking a
tree 6 or 8 inches in diameter, would have little or no effect omnits
vitality if scattered over the trunk from the base to near the top, but
if concentrated on a limited space on the upper part of the trunk, and
distributed so that there is a gallery at intervals of about every
inch of the circumference, forty or fifty galleries are sufficient to so
seriously affect the tree that other insects are attracted to it, and it
soon dies from the girdling effect of the primary galleries and brood
mines. The marks of as many as seven galleries were observed in a
single chip, 6 inches wide and 12j inches long (P1. Iii, fig. 2), cut from
a tree that had been killed by the beetles. This, with many other
observations relating to the number of pitch tubes on freshly attacked
trees and the galleries in the bark of dead and dying ones, indicates
that the average tree killed by the beetles has from one hundred to
two hundred galleries in 30 to 40 square feet of bark from the middle
to base of the main stem or trunk. The number of eggs deposited
in each gallery depends on the number of galleries within a given
area of bark and the success of the attack. They vary from one or
two to about one hundred, but the normal number appears to be about
forty to fifty. If only one-half of these develop to adults there are
four thousand or five thousand beetles to emerge from a single tree 8
to 10 inches in diameter. Therefore the number of beetles that may
emerge from the thousands of trees that die in a single year would
make a swarm of millions of individuals. Even if this number were
reduced one-half, it will be readily seen how the trouble may be
rapidly extended over vast areas of forests.






19


CHARACTERISTIC FEATURES OF THE LIVING, DYING, AND DEAD
TREES INFESTED AND KILLED BY THE BEETLE.
The characteristic features which are of importance to the forester
and lumberman in identifying the presence and the work of the pine-
destroying beetle are as follows:

BORINGS AND PITCH TUBES.

The first indication of attack is the red dust or borings lodged in the
loose bark and fallen around the base of the tree. The next and more
conspicuous evidence is the presence of numerous small miasse.- of pitch
or so-called pitch tubes on the outer bark at the mouth of the entrance
burrows. (P1. VII., figs. 1, 3, 4.) If the pitch is fresh and mixed
with reddish and white borings, it indicates a recent attack and the
presence of the living beetles in the bark. If, however, the pitch is
dry and hardened, without traces of fresh borings or the presence of
living beetles, and the tree is living, it indicates an abandoned attack
and that the tree will recover.

APPEARANCE OF THE LEAVES.

The leaves of trees dying from attack by the beetle present first a
pale-yellow appearance in the tops and tips of the branches, followed
by a general yellowing of all the leaves, thus presenting from a long
distance a marked contrast to the dark, healthy green of the surround-
ing living foliage. If the bark is stripped off and examined when the
trees are in this condition, all stages from eggs to fully-developed
broods will usually be found, together with numerous other secondary
enemies of the trees and enemies of the insects. The leaves do not
fall from the twigs for possibly two or three years after the trees
die and the broods of beetles emerge, but they soon change from yel-
low to red, and thus become even more conspicuous. The normal
length of time the leaves remain on the twigs has not been determined,
but the greater number evidently fall during the second or third year,
leaving the twigs almost bare, with the exception of a few leaves on the
tips which may adhere for a much longer time.

APPEARANCE OF THE TREES THAT HAVE BEEN DEAD THREE YEARS OR
MORE.

Little opportunity was had to obtain information on the character-
istic appearance at different stages of deterioration, but it would appear
from such observations and general comparisons as could be made that
the twigs and some of the branches commence to fall within three or
four years, and that after the fourth year rapid decay sets in, and the
tops commence to break off.






20

EVIDENCE OF THE WORK OF THE BEETLE ON OLD DEAD TREES.

After the trees have been dead many years most of them decay at
the base and fall, while the main trunks or snags of others remain
standing; yet as long as the surface of the wood remains sound the
characteristic longitudinal gallery grooves will be more or less distinct,
and serve to indicate that the trees were attacked while living. Pieces
of the old bark will also usually show traces of the galleries and indi-
cate by the pitch-preserved tissue that the galleries were excavated in
living bark. Traces of the pitch tubes may also remain on the outer
bark for many years and serve to indicate the cause of the trouble.

RELATION OF WOOD-BORING INSECTS AND WOOD-DESTROYING
FUNGI TO THE RAPID DETERIORATION OF THE WOOD.

As previously indicated, there are a number of wood-boring insects
which bore into the sapwood of dying and dead trees. Some also
penetrate the heartwood. Some of these wood-infesting insects enter
tne wood as soon as the tree commences to die, others after it is dead,
and still others at different stages of the decline and decay as long as
there is anything left for them to work in. It is only those, however,
that enter the wood while it is yet of value for commercial purposes
that need to be specially mentioned in this connection. Next to the
one that makes the primary attack, those borers which enter the sound
wood are probably of the greatest importance. They not only cause
pin-hole and wormnhole defects, which depreciate the value of the lum-
ber and other products into which the wood of the dying and dead
trees may be converted, but they give entrance to wood-decaying fungi,
causing rapid decay of the wood of the standing trees which would
otherwise remain sound for a much longer period.
While the injuries by these wood-boring insects are by no means as
common where there are a great many dead and dying trees as where
there are only a few, it was found to be sufficient in some sections to
cause, in connection with the wood-decaying fungi, a worthless condi-
tion of the timber over large areas. Indeed, it would seem from such
observations as we were able to make that unless the trees are cut
and converted into lumber, ties, cordwood, or other commercial prod-
ucts within two or three years after they commence to die, very little
of value is left.

SUGGESTIONS FOR PREVENTING LOSSES.
The limited time devoted to the study of this new insect was not
sufficient to determine the details in its life history and habits which
are usually so necessary in the consideration of remedies, but some
general features were noted, which, in connection with the information
acquired from special investigations of the closely related destructive








Bul. 32, New Series, Div. of Erntom-ilo), U. S. Dept. of Agricultuie.


PLATE VII.


FIG. 1.-SMALL FRESHLY ATTACKED PINE TREE, SHOWING
PITCH TUBES.


F3. 2.-MARKS OF
THE SURFACE OF
REMOVED.


PRIMARY GALLERIES ON
WOOD WHEN BARK IS


FIG. 3.-FRESHLY ATTACKED TREE, SHOWING PITCH TUBES.
ADJOINING TREE NOT ATTACKED.


FIG. 4.-DEAD TREE; OUTER BARK REMOVED
BY WOODPECKERS.


SCENES IN THE PINE FORESTS OF THE BLACK HILLS FOREST RESERVE.









. 21


pine-bark beetlea of the middle Appalachian region and the spruce-
destroying beetle b of the Northeast, will warrant, it is believed, some
suggestions for the prevention of losses.

METHODS OF COMBATING THE ENEMY AND PREVENTING LOSSES FROM
ITS RAVAGES.
When a trouble has been going on six or seven years and has
reached the magnitude of the one under consideration, it is very plain
that unless some natural agencies appear to either modify or check it,
its control is beyond all human effort. On the other hand, if there
are beneficial influences at work which are reducing the numbers of
the insect and checking its destructive ravages, there is much that can
b- "one toward aiding nature in the suppression and subjugation of
an ur.ruly species. The evidences found indicate that the latter is true
in regard to this trouble. While many freshly attacked living trees
and thickly infested dying ones were observed in different sections of
the reserve, showing that great numbers of the beetles are at work
and continuing the trouble, it was plain that the force of the attack
has from some cause been materially weakened.
TO REDUCE THE N'l'.MBERS.
It appears that the pine-destroying beetle of the Black Hills, like
its Eastern relatives, depends on the trees killed by it for the aug-
mentation of its numbers and the perpetuation of its power of killing
more trees. Therefore it is only necessary that the attacking force be
further reduced to a point where it can no longer overcome the vital
resistance of the trees on which it concentrates its attack, in order to
successfully defeat it and secure its extermination.
The fact that the attacking force of the enemy is already weakened
from natural agencies suggests that they can be reduced by artificial
means below their power of killing more trees next season, and thus
bring the trouble to an end. Therefore the following are suggested
and recommended as probably the best methods of accomplishing this
result:
(1) Determine the location and extent of areas in which trees were
attacked during the summer and fall of 1901 and the number of trees
now infested with living broods of the pine-destroying beetle.
(2) Select those areas in which there are the largest number of
infested trees and mark the same for cutting.
(3) Secure, by sale contracts or otherwise, the cutting of these trees
and the removal of the bark from the infested parts of the main trunks
and stumps prior to the 1st of May, 1902. The drying of the removed
Dendroctonus frontalis (Zirmin.) var. ) destrtfo Hopk., Bul. 56, W. Va. Agri'. Exp.
Station, 1899.
bDendroctontus piceaperda Hopk., Bul. 28 n. s., Div. Ent., U. S. Dept. Agric., 1901.




A.P


22

infested bark and surface of the wood will effectually destroy the
insects. In addition, the logs so treated will be protected next spring
and summer from the attack of wood-boring insects, and thus be
almost or quite as valuable for all commercial purposes as if cut
from living trees.
It is not necessary that all infested trees in the reserve or those of all
other infested areas should be thus cut and barked, but it is important
that a large per cent should be so treated in order to insure a sufficient
reduction of the beetles to check their destructive ravages.

SUGGESTIONS FOR PREVENTING FURTHER TROUBLE.

It is believed that the prevention of further trouble may be effected
by means of girdled and otherwise treated trap trees, but the best
method of treating the trees and the proper time or periods to do the
work remain to be determined.
No experiments of this kind have been conducted with the rock pine,
and it is not positively known when the beetles commence to fly or what
is the period of their greatest abundance or swarms. Therefore it is
suggested that a special line of experiments be conducted, between the
1st of May and the 1st of September, to determine the best methods
of providing trap trees and the best time to do the work to secure the
desired end, viz, that of attracting the migrating beetles to certain
trees or sections of the forest, where they can be subsequently
destroyed by cutting the trees and removing the bark.

TO PREVENT LOSSES FROM WOOD-BORING INSECTS AND WOOD-DESTROYING FUNGI.

The evidence found relating to the work of wood-boring insects and
wood-destroying fungi, which cooperate in effecting a rapid deteriora-
tion of the trees killed by beetles, suggests that all trees should be cut
within three or four years after they commence to die, the sooner the
better, and be worked up into lumber, ties, mine timbers, and cord
wood, in order to prevent the great loss of valuable products which
would otherwise follow. Such-material, if in excess of the demand
for immediate consumption, might be stored where it would keep dry
and be protected from fire. It would thus remain sound for many
years and serve to supply the demand for material which would
otherwise have to be drawn from the living timber.
*
THE PROTECTION OF LIVING TIMBER.

Since it is of the greatest importance that the living timber in the
reserve should be protected and preserved for the heavy demands
upon its resources which, owing to the vast mining, commercial, and
other interests, it will be required to meet, the prevention of unneces-
sary cutting on account of injuries, or alleged injuries, from insects
should receive special attention.






23


EVIDENCES OF UNNECESSARY CUTTING OF LIVING TIMBER.
One of the special objects of the investigation was to determine
whether or not unnecessary cutting of living timber had been done by
certain contractors who had purchased, at a reduced price, the speci-
fled "bug-infested" and "bug-killed" timber. Therefore, upon the
request of Mr. Pinchot, the wi:iter made a careful study of the con-
ditions found in an extensive cutting in a "draw" east of Dead Ox
Canyon of Big Spearfish Creek.
Much conclusive evidence was found that a large per cent of the trees
cut here and worked into railroad ties had been living and uninjured
by insects when felled. The evidence may be briefly stated as follows:
All trees that are attacked and injured by the pine-destroying beetle,
whether in small or large numbers, plainly show the characteristic work
of the beetles in the bark and on the surface of the wood. as previously
described (p. 17) and illustrated (PI. III, fig. 2; Pis. IV, VII). The
character of the work will also indicate whether or not a given tree
was living, dying, or dead when felled and the bark removed. The
operation of scoring, hewing, and barking the ties in this particular
cutting had evidently followed closely the felling of the trees. There-
fore the inner portion of the bark and outer or adjoining portion of
the wood of the scoring chips and the barked surface of the ties from
"bug-infested" and "bug-killed" trees bore abundant evidence of the
work of the insect and the condition of the tree when felled, while
those from healthy living trees, not injured or infested by bark-boring
insects, showed no traces whatever of the work of the beetle or of any
other "bug" or insect.
The records of ties, counted as observed in the woods and examined
for the work of insects, show that out of 207 ties only 55 bore evidence
of having been cut from "bug-infested" and "bug-killed" trees,
while the other 152 bore no evidence of insect work on the barked
surface, but showed from the condition of this surface that they had
been cut from healthy, living trees; also that some of the trees had been
cut in the winter when the sap was down and that others had been cut
in the spring when the sap was up and the bark would peel. There-
fore it would appear that a large amount of living timber had been
cut which it was plainly evident the Government desired should remain
standing.
SUGGESTIONS CONCERNING TIMBER-CUTTING CONTRACTS.
In order to provide or guard against the cutting of living, uninfected
trees, along with the seriously injured and dying ones, it might be
suggested that it be plainly stated in contracts and instructions that no
living tree shall be cut which does not show, in the inner )ark next to
the wood, the presence of large numbers of living insects, of the species
known as the pine-destroying beetle, or any other insect or insects
which may hereafter be designated as destructive enemies of the trees.








NEED OF FURTHER INVESTIGATION.
While considerable evidence was found during the time devoted to
the investigation, there yet remains much to be determined by detailed
study and experiments relating to the peculiar conditions which bring
about the invasion of a rare or new insect and the conditions which con-
tribute to its rapid multiplication and destructive work, as well ay those
which contribute to its decline and sudden disappearance. There are
also many facts, yet to be determined, relating to the life history and
peculiar habits of the pine-destroying beetle and other numerous
enemies of the trees, and the natural enemies of such insects. The
determination of these facts is very necessary in order to suggest the
best methods of preventing losses in the future. It will also help us
to utilize nature's methods of protecting such of the species as are of
use to man and destroying those that are objectionable.
Cutting and barking the infested trees this winter would be an exper-
iment of great importance, not only in its prospects of ending the
trouble, but in demonstrating whether or not it is a practicable method
to be adopted under similar conditions in the future. It will also be
of interest, and probably of considerable economic importance, to note
the effect that this process of insect destruction will have on the other
injurious and beneficial insects involved.
iThe experiments of girdling, cutting, and treating trees with a view
of rendering them attractive to the migrating beetles, and thus pro-
viding traps for them, is a line of work which should receive special
attention next summer. It would serve to demonstrate, or at least
indicate, several things which it is quite necessary to know in order
to adopt successful methods of preventing future trouble from insect
ravages on the pines of this reserve. It would demonstrate whether
or not the beetles that emerge from the infested trees which have not
been cut and barked could be attracted to trap trees; how and when
the rock pine can be girdled or treated to exert the greatest attraction
to the principal enemies, and how the insects thus trapped can he
best destroyed. It would also contribute greatly to the study of the
life history and habits of the primary and secondary enemies of the
trees and the enemies of the insects.
There are other features relating to the kinds of insects and fungi
that attack trees girdled by different methods, or girdled and felled at
different times of the year, which should he determined. Indeed,
there are many and varied subjects relating to the insects of the rock
pine which should be studied during the progress of the present
trouble, in order to accumulate data that will be of service in prevent-
ing and checking future destructive invasions in the pine forests of the -i
Rocky Mountain region.





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