tS: /~* 1
', '* * 'I *
I " .. I 11
U. S. DEPARTMENT OF1 AGRICILTLTRE,
BUREAU OF ENTOMOLOGY CIRCULAR No. 143.
SL. 0 HOWARD. Enlomolgou and ChWl ol Bureau
INSECT )DAMAGE TO STANDING TIMBER
IN THf[J NATIONAL PARKS.
A. 1). HOPIKINS,
Il ('hargr .f Iorrst I .. .. l .tii.ijiflet,.us
19240'-Cir. 14;t I
' .1-Hi'I..;% .-~. a IlI r.%' I P' i, i'1. .4IFl- K rI)
If 'RE' I Vfl' i:\TfOIi un, (GY.
L. 0. IIOW.AD. Eiil'iiloifolgi.t atil f'iiref 'f Bur.aoi.
C. L. MARIATT, iit 11oiilitgi.I i(F .Irling ('h if in Ali-.Rr'v of <'hivf.
IN. S. Cu('LrrTON. Eri< tllrel' .l,.i.,hild.
W. F. T'AsiIT. (liiif Clil.
F. H. CI- ITTI. NIEN. in r-iargc of tru( A- crop and .torrd product inl'r-I iIIr Itiga vlin n.
A. 1). HIOI'KINS. in, ht iigv if fu r( i inii'rl in''fui fiti'u.
W. D. IlurNTrr. in cli'ij' of soulvher' fi
A. L. Qu \iNTA. NI. itn c.h/rge of dec.idtioniiq f.ritf iert inr,'.t'gatinns.
F. P. PIIILI II'.S. in Cliiitili of br, c'illurte.
D. M. ROOGRS, in I 10n i if pii'i'titii 'prinl ,if niitlih i. field work.
ROLLA P. CURRIE. in vliaf',< of cdlitiiil ,,rk.
M.\BI':L Ci) (ORn. in c(liiire rf lihrnrri.
A. D. HOPKINS. in dfiargf
H. E. BURKE, vittrovl',,givu'l nas.sistnt. il (char r ,,f Fr,rct n.,rert Field Rtation 5,
Y, I'l,. Cal.
W. D. EDJMONSTON. qigt tit (inl 'trpCrt, in rlcvivr of Fi'-rrtf In-. 'l Fid Staftirin 6.
K'luiiitli J:rl' .//>, O 'r4.
JOSEF BRUNIE:R, agcil a :t expert. in (hvrpai .f 'orrl-it ljjrt Field S.tation 1.
v'oiiiitotb''i l' /l., A/ont.
E. B. Mason. enlomttilciqir.,l nssilanil. in thi-rge of Fori't stl Insect Field Station 7,
Spartanburg, 8. C.
.'. E. SNYBER, '"i1 ll iil r'i, c.rpirt. 11g1g1fl in. i rligation.s (if in'ret dutmage to
lvlegraphi and telephone poles.
J. L. WEBB. entvonoleigiv'il as.i.tatit, xprcilivlt ,m- rrlnitibyviuil betl'.es and larvtre.
S. A. ,OI 'WLR, agent ail eCxpCer't, .ipeeiali.t ,ini; ,nflti x i Tp7"ntliredinfoiden).
IMARY 1-: F\uNCE, MARY C. JOHNSON, MN 'DF T'YI.Orn, ELIZABLT RI'TCHIE. pre-
CIRCULAR No. 143.
United States Department of Agriculture,
BUREAU OF ENTOMOLOGY.
L. 0. HOWARD, Entomologist and Chief of Bureau.
INSECT DAMA(UE TO STANDING TIMBER IN THE
lIy A. I). IHo'KINs,
III V'liiijly, f "l, .1 Insfecvt In' Irl, tii .
CHARACTER OF THE DAMAGE.
The da(in:igt. I isIects t to the i itwI trees of t Ihe forests and orna-
nimentaiil grino, l ,f tohe national iI-.k- consists of injuries to the
foliage, b:, lin'he-. or the entire tree which mar or destroy their
:itt rat'tiT. edIt' iiiini.11. iinI historic ft. iiurv- and dimi nish or destroy
their coimmer'iiV: .ilue.
Throughout the fo-i:-. of the Rocky M.itii:i;ini a1nd l';,, iti' -1,iv 1.
includin- the n.itiontal p),.I- a 1;r.,i. ]g. t' iii:l., of the timber has
died during tlie -i't half century. The oldt -tittliiIIr, and fallen dead
trees, thle red foli.ia- of those that died last year, and the f,i'l._.
tops of those now tltdying l e:lr evidence of the work of insects and
are conspiuuiti, exaniplei, (Of a gre.it waste of fore-st resources. In
,-,iie locaIllii,- :t f.w -c;atturini trees die each .., r within a town-
s.hip or -eetion : in others, clumps of trees or whole forests die ,liirin.,
:i -ingle year.
The 'onrifer-. \'vi ich are the predi l,, 11 tiiiiL, trees of thi western
part of thlie coilrY'. are -iihiject to a liigli datli rate fr,,i, insect
attack-. The pilit-. the -'*ru't.-. tlh I)t- .iul: fith. the balsam lir-.
Sthiehetltbck+. the cviL,;ir'. and the SiTti a (i,.l,,iil.) have each at
len-t one de-.trtt,'tin'e ellt'irn.
In the f.ll. ,priLg. and e;irly summer the dying, i and recently ,Ilail
treet- art' cini-pieti-t on account of their fi'111. ^ellow i-li]-rnil. :nidl
rteillish-lbrotn foilig-e. a.;i if injury, il l finr. 'l eiin tihev art in'
large platcie-. (ir extenil over ai con-iiikr: ili li' a'ra.i their death ii
often attributed by the c.raunl olberver to forv-t.4 fires.
'This paper ws ad by the author at a ,-nnferenreP of national park uplrntendents
h i.d'I unI .r It he of theI S ..r.-tar% of thIe intertor. S-.iapnbh. r I -1-. I'll 1. and
II. embodied In the prot-dinira of the meeting s d Ny the Interior Drpartment
I II-IJan,;ary+ T, .II[_'
2 INSECT DAMAGE IN THE NATIONAL PARKS.
EXTENT OF THE DAMAGE.
The extent of the damage to the forests by insects through the
accumulation of dead timber and the dying of matured trees over
l-rge areas is vastly greater than the general observer would suppose.
In fact, the dead and fallen timber is so common in all forests that
it has heretofore been recognized as a natural and inevitable condi-
tion. Large areas of insect-killed timber have been charged to fire
without further thought or examination to determine the real cause.
Fallen timber has been attributed to storms, and scattering dead
trees to old age.
During the present year a reconnais-ance was made of typical
sections in one of the national forests, where there was no evidence
that destructive forest fires had occurred during the past 20 years.
It was found that the standing and fallen dead yellow pine that
had died within that period amounted in board feet to nearly half as
much as that which was then living, and of the sugar pine and
Douglas fir there was one-fourth a-s much dead as wa:i, then living,
and every dead tree examined in the estimate showed evidence that
it had been killed by insects.
In the Black Hills Natiunal Forest of S"outh Dakota over one-half
of the timber died within a period of about 10 years. In Oregon
and Montana nearly all of the larger pine died within a few years
on areas of a few hundred acres to 100,0100 acreb or more. These
together with many other examples of extensive dying of timber
have been investigated and found to bie cau.ted primarily by insects.
Investigations have also demonstrated beyond question that a vast
amount of timber is killed by in.iects every year within the forested
areas of the Rocky Mountain and Pacific Coast regions. Further-
more, the accumulation of this dead timber and fallen debris is a
menace to the living, because it furnishes fuel for destructive forest
fires. The losses from insect depredations are thus augmented by
* The extent of damage to the forest and other trees of the national
parks has not been estimated and. with the exception of investigations
conducted in the Yosemite and Glacier Parks, we ido not have much
direct information as to the damage already done. It is plain to us,
however, that the general conditions are not different from those
which prevail throughout the regions in which the parks are located
and in which the destructive species of insects aire known to occur.
The amount of damage in the parks must be considered not only
on the basis of the commercial value of the forest resources, but on
that of the aesthetic and educational value of the virgin forest with its
typical examples of tree :-pecies.
The loss of a section of the forest which forms the attractive fea-
ture in the landscape, or is the only remaining example of the origi-
IMl t iVp of fiorc't gri), tll of tlhat .it> iin. is fi r ,gi.ili than ilinit rep-
re.e I'tlttI lI bv Ihe c'niilunrciaiil %,iliI, i)f the timIber ; as is al ) the notable vt terans iiliid giint oif the il l t'riiiit species. 'ITl-t. old f,, vI-.
andi Al tIrt.s iire at lw'-.fit one f the attractive and instructive f'
tiure. (if lilt iiiiTl, areas ,f some of the national lirlh;. and if they
are prittteed front their insect wi,,l oth we enemie's li\ will 1te even
ll()'t' alltn'tot'ive f,,'ituIIr, in II n ni cei nt ris l-. Inder )r'e-enIt condi-
tionl'. tIr-i' ohld trees of the iiii,,i I forest aI re i ..I I '- .tl, r ,l. iiir r of
being killed lbv ii...ct- than are thile .% ii Ir.I tr es, II'ti .,l. ii.'i,, of
tlhein Iill't' blen kilie'd % ithiin r i-cent \;i rs-.
Tihe three ginitt .sllgalr pines on tihe trail from Wawona to (Glacier
Point aiwl the Yo.einite VHill C are examples. Two (If themI were
dead aniid the other was ildying when I saw them in Jiic, lil44k :;iil
there wits oinclii.ive evidence that their death was caused I the
Inountilin pine betle. Tli'e veteran -nZMr ]Pint. known as l'nlh
Ton." wa-, iwing attacked at that time by the same species of 1itlie.
and I lin inifornmid that it died the flliinuir yv.ir. TIe loss ,If these
four giants of thei' lpeciv- is irreparable.
The Sequiloilas are .Ulppor,-.ed to he inmmiune to the attack ,if insects.
but they nre not. They are more resistant than other :| ,,i -. and
tlihat is one reason theyl have lived so li, 'ii,. llowever, t.i..l. -pcie.
hia- n 1'a Irkleetile enemy v.,i-hili. under favorable conlit i,,,. is capable
of killing. tlhe IntrL'et and finest speciIImens-. I saw one of the 1;ir-gt
redwood, in the vicinity of EA reka Cl. that had been killed by its
harkbeetle enemy. and \\When in the .M.i'iposa (rove, in I iilI. I dis-
covered thie barkbeetle enemy "f the 1'iNZ tree in the IV inig bark of a
THE PRINCIPAL DEPREDATORS.
The nimere mention if the names ,f thie thousands of species if in-
sects. ea'hI of which causes some i,, Auliar iiijiiurv lridna the life of the
different tree -pevit-. would occupy umore space than is .illolt.ii for
this patIper. Thcfr-fi wre Nmust ,.iii-iiir thle more iiiirant of tli.e
which are dirlectlyv J.-pi,,ilih, for the ilt.:illi of th,, trees.
The little ir tniii- of Mh'i'lrii tliiln l ,t '-. or 1rcT-killiii l ,.ng ici'. is
representedil in the R,,.ky l intaiii .inil Pacific Slope Ir.i,,n. 1\ a
few specie- which a re moe hti-I r iive to the conifer- of weVte'rn
North A.merica than all other fo e-( insects combined. Tln'y are a
constant mIenace to the pine. -irni I.. and D,11iJ.l.i. fir of the national
parks-. They are certain to be Ire'-eil in every p.iik in which there
are forests; of their host trees, and have hIwhiiliilh- caused far greater
damage than the pIrk WfAic'il-. have r':nilinild.
The species, in (lite nutl'i f their Al.-Iiriii 'i Ic--' are th. iiioiii it iiin
pine beetle, the western pine bItle. the Eni _'lill:t nil ..liire bet'etle, the
IN t'f Il\.M .' IN,l IS I, 11 % \l |IN %1. I' ."h-
INSECT DAMAGE IN THE NATIONAL PARKS.
Jeffrey pine beetle, and the red turpentine beetle. All but the Jeffrey
pine beetle of tlhe Sierras are common to the northern Rocky Moun-
tains and the Pacific Slope. Those common to the central and south-
ern Rocky Mountains are the Black Hills beetle, the Engelmann
spruce beetle, the Douglas fir beetle, and the red turpentine beetle.
There are three other species commIon to tilhe southern Rocky Mount-
ains and northern Mexico which are of less importance in causing
the death of trees.
These insects are small, stout, black to reddish-brown beetles, rang-
ing in length from about 2 mm. to 9 mm.. or 0.08 to 0.36 of an inch.
They fly in the period from April to October and attack the main
trunks of the living healthy trees by boring into the bark and ex-
vavating long winding or nearly straight egg galleries between
the bark and wood. In this manner they completely girdle and thus
cause the death of their victims. As soon as the bark begins to die the
eggs deposited by the beetles hatch and the young grubs, or larval
forms, complete the destruction of the inner bark. All of the broods
develop into the adult taige within a year and emerge from the
bark to fly in search of new victims. Each species has its peculiar
habits in the choice of host trees, methods of attack, and period of
THE MOtUNTAIN PINE BEETlI.E.
The mountain pine beetle attacks the mountain or silver pine, sugar
pine, western yellow pine, lodgepole pine, and evidently all other
pines of the northern Rocky Mountains and the Pacific slope. The
adult beetles fly in the period from July to October, inclusive. When
abundant they concentrate their attack on clumps and patches of
trees. Their long. nearly straight egg galleries and radiating larval
mines soon kill the bark on the main trunks, but the foliage of the
infested trees remains green and apparently healthy until the follow-
ing May and June. It then begins to change to a pale green and
later to yellowish and brown. By the time all of the foliage is dead,
about the 1st of July, the overwintered broods of beetles begin to
emerge. By the middle of August most of them are out of the dead
trees and have entered the living ones.
This is by far the most destructive insect enemy of the pine within
its range, and under present conditions is a constant menace to the
forests of matured or merchantable-sized timber. It can be con-
I rolled by felling the infested trees a;ind by removing the infested
bark from the main trunks without burning the bark or tops. This
work must be done during the period between the 1st of October and
the 1st of July to destroy the broods of the beetle before they emerge.
-Whenever the timber can be utilized the product will pay all ex-
penses. If it has no commercial value it will cost on an average
50 vents i tuI'e fi t Iti- reiiiir'td trei tmi ent. .\ fier an InItlir,;ik is
. u under ni'it r I t live li\ in i, timberi can I* easily i lv I I 'it fI',,Ir fI-1iir tir
dlepredations. by giving )r ,iiiill rilltiilin to the fIllir ili& nl liirliiig.
of any clumps of IlYinig trees fInilll 4111 11i il'. M .y a 1i t June. it 111 -4
or fire p:l e Iuriinii bIl e insItrucII ted o li: ( III-v can do tli)i, and a;iny-
thing l.le thl ilt is 10iiiir1 il to iiiil.i ili i tiil l,
Ill U lt-hI'': \ PINE IIEIIThE.
The esiternt pi ne le attacks the we clterl yellow vi ne. the d 'ic1:i r
pile, aind tie .Jet'rey pile. l'he Iettles fl.\ iln lite Jmune to ().-ii.r
inclusive, and U1ilili v alt.ck s1 tr i'rin, di v PI 1ua I ii r--, 11i ifi select-
ing the larger anild oiler vxailiil-l'. The inlil- excavate wiIIinIiiP
egg galleries between the inner living bark and the wood and trains-
form it to (li adult t (;ige in the outer bark. Tli, beetles ,l, gin, to fly
aind attack the tre in Junime and corntinu the iattak until October or
November. Thie tinrt geiirartilmiii develops anId Iii lln' i A.\i-r-t to
Novemberr, and tflit- .r'miid1 eneration pases the winter in the trees
that are killed lby it in the summer and f.d ill.
The foliage of thie infestcl tree bDe.iii- to ft;,le and urn yellow in
a few weeks after the trees are :AtitAkrld by (iii- beetle. Thie summer
broods of thie fir-st genlralioTI leave the trees by the time the folingr
is reddish brown. butil the overwintered broods do not vilerge until tle,
following May and June. in some as several months after '#Ic
foliage is brown.
This ,pTecie-. is next in inuiporiainii to the mountain pine beetle
as a destructive enemy of the pinl,. and the two spvcis often volnliilr
in their attack. In this combined attack the western pinch beetle is
a .econdaryv enemy of the trees lwase it f,ll,\v- the attack of the
other species. When it is the primary enemy it is rf-.poln-ile for
the death of a few scatterinl tree each \e'i. thrl'liuglmll the foret't
which re-uilt, in the accumulation II' dead timber. In the a p'-
gate, this crunumniiative loss i vel"ry' extenllsive, invl ing. as it d,.Pe. the
largpe-t ind lIw-t trees.
The insect ailn Ne onitr-olledl 1nd the living t iliil-r protected flroin
its ravages bw felling the infested trees diiri-niL the pleri di lvtv eni the
1st of October and thIe 1st of June lind 'remiovin the birl; from the
main trunk., nd hilrniing it. It is neces.a-.'ll to liiiuni the ark because
the broods of this species transformi in the outer .inirk. They are not
destroyed by simply expoin., the inner bark, as is the case with the
mountain pine beetle.
THE JEI-t'RY PINE BEETLE.
The c'hairacteristlic hahits of the .Jetri''y pine lutlei are similar to
those of tire mountain pine beetle, liand hercfiefirt it requiires.- the ame
rNs' l'' I* M M %,.I- IN 1" 1, \% \ i, %I, I'1I KS.
INSECT DAMAGE IN THE NATIONAL PARKS.
THE I)OUGLAS FIR BEETLE.
The Douglas fir beetle attacks the I)ouglas fir, the big-cone spruce,
and the western larch. Thie beetles fly in April and May and enter
the living bark on healthy trees and on trees that have been injured
by fire and those that have been recently felled. In habits of attack
and general clhiaracteristics the Douglas fir beetle is similar to the
mountain pine beetle, except that the former begins to fly earlier
in the season and the foliage of the trees infested begins to die in
the fall. It is very destructive to thle Douglas, fir throughout the
Rocky Mounta.in region from British Columbia to Mexico, but is
much less so on the Pacific slope, especially toward the coast. It
can be controlled by felling the infested trees during the period
between the 1st of September and the 1st to middle of the following
April and removing the infested bark from the trunks without
THE RH) TURPENTINE BEETLE.
The red turpentine beetle is the largest species of the genus Den-
droctonus. It begins to fly in April and is active until October and
November. It attacks the pine and rarely the spruce. As a rule it
confines its operation to the base or basal portion of the trunks.
While its normal habit is to breed in the bark of stumps and logs of
newly felled trees, it often infests the bark on healthy trees. It
rarely kills a tree, but is tlhe cause of a large percentage of the basal
wounds known as "cat face-" and fire wounds, so commonly met
with in the pine. This is a far more difficult species to control than
the others because it breeds in the stumps of felled tree,, and the base
of those killed by the other species or by fire. Valuable individual
trees can be protected by cutting the beetles out of the bark as soon as
their presence is indicated by ni masse. o(f exuding resin mixed with
reddish boring dust.
Wherever there are continued lumbering operations the red turpen-
tine beetle confines its attack to tlhe stumps, but in the national parks
and private grounds where a limited amount of timber is cut, or
where the ravages of the mountain pine and western pine beetles
have been controlled, it is likely to cause more or less extensive dam-
,ge to the living timber for ai year or two after.
In combating the other beetles in the national parks, care should
be taken to remove the ;bark fro n the stumps \h never they are
found to be infested with this pest.
TIHE EN;I:L31.A N N SPRUI(E BEETLE.
The Eiigeliiianni spruce Ieetle attacks the Engelinann spruce, blue
spruce, and any other species of spruce found within its range, but
IN I,'T D.M I;I: IN ri1il N II'\INL. I'lKS.
dloes noit tta1ick the pi li.. hI ii,,I I. li", or I lI am I 1. It I ,.- t in the
period from .uiille to A ulgust and attacks Ihe I, irk of t1e 111 11111 trunt ks
(if tlie older or nitlt'iiid Ire.,. Its habits a:ret similar to ths'e ,,f the
inoiin liii lliiille 1beetl', except that it II'',. earliiir n the1 -iii]'.'. \'lh Iii
i(he tret's Iliell to ilit the ;il'e fail, to a 1pale i 1'1ri ia d iill Ii.fi.
they chanlle to yvellow or I lio i. biut the t :re iw .I- lpresentli a ,iLi 'ili-
irown iippeiariiarlce. The iift-'ti.Il Iri'.- are eas-il, located in lhe faIll
iand early prilil 1iv thile f;dliIhi nlcedl.- :ind the hare 1\ i,.- o" tlhe tops.
Thi'is speries o'iitll from Iiili-li t'nliai:i t< NI'\i ', and at
limtnes i. wr"rv diSi lriictliv, to the 1 ':ii.4h .iiiii1 -I iii, II v .- -. It :lan
Ile controlled by fby il h the infested trees aIlII '-,.\ iii r thlie bark
froiin the iniin trunks dirinig the period piiI,,iiL- with the l-It of
October and ellintl liY the middle to last (f 4WINt.
THlE BlACK IILLS IliTU:H .
The Bliack lill s betih, is by tf:il the illo-t des-tructive insect uiatmil
of the pine of the central and southern lcei- y M'l ,,i1itt ,i, and the
Black Ilillk of S tmtlli Dakota. Its habits aire similar to those -if the
iiioun.lin t iin il elhle. and the same Iuethods ari :iii,,i,.ul flor its
cont ro I.
FAVORABLE CONDITIONS FOR THE BEETLES.
There are certain conditions in the administered as well as in the
nat urail fore-.& whicl contribute to the multipliciat ion and destructive
work of these Dendroctonis beetles. One of the miost favorable con-
ditions is an extensive fI I>t ,If matured and old trees (if pti i, or
lrniuce. because in the bcliniiin., If anl invasion such trees are more
often thlie first to be attacked and kill,.l. Trees in such a forest
injured by lightning or storms ft ci form centers -if infestation in
which the beetles increase to suiii1i11t numbers to Vniailde, them to
kill a few t rees, and lin the invasion is -I. irl'l. veail aI. fter year
increasing in roi. until a l-pi'e it,.ri'nlagt, or all of tih, old timber is
killed. The beetles then attack tihe vmllig trees and ofliei waste their
energies on -.aipl1ings. in wIircli thile tr,.,oi fiiil to d'Iv lllp.
Drogighf.-It is a common belief that severe ,lrumglt. weaken the
tree-, andi thus contribluite to fa ,imralhlel conditions fior thle attack of the
beetles. We have madie a very tioroiivh inv,-igti'.ion of this sub-
ject nnd are led to concl ie that exI-eptint;i ll ,ry seasons are more
unfavorable for the development of the beetles tliin are niloderit.ly
humid ones., and that, therefore, drouig,,,ts do not contribute to their
Forest fr, s.-Forest fires contrilaite, to a liiiteiiid \iixt. to the
multiplication of certain species which breed in fie --. archedd tree-.
but as a rule forest fire, kill more beetles than pI,, protect.
INSECT DAMAGE IN THE NATIONAL PARKS.
Conmmlr'V;al cettijig.-Commercial cutting of timber may contrib-
ute to the multiplication of certain species which breed in the stumps
and tops, but if the cutting is continuous the insects confine their
attack to the cut-over areas and do not invade the living timber.
Sporadic summer cutting, however, is dangerous. The odor of the
cut wood attracts the flying beetles to the locality. This contributes
to their concentration, and when the cutting is stopped they invade
the living timber.
Secondary enemies.-The secondary enemies of the trees consist of
numerous species which attack the bark and wood as soon as the
trees become weakened and are dying from other causes. The Den-
droctonus beetles are the primary enemies or leaders in the attack.
The secondary enemies are, to a certain extent, their allies, and
when very abundant may contribute to favorable conditions for
rapid advance in the destructive movement, but more often they
are dependents and scavengers, merely utilizing the dead and waste
material. With rare exceptions these secondary enemies are not
capable of killing trees on their own account.
UNFAVORABLE CONDITIONS FOR THE BEETLES.
The unfavorable conditions for the destructive work of these
Dendroctonus beetles are to be found in administered forests where
the ripe or matured timber is utilized and where the young timber
is protected by the prompt disposal, during the fall. winter, and
spring months, of any clumps of dying trees.
In other words, systematic forest management based on a knowl-
iedge of the principles of silviculture and forest entomology will
soon present conditions so unfavorable for the Dendroctonus beetles
that they can no longer exist as agents of destruction and waste.
The natural enemies of the beetles serve as a repelling force against
the progr.-i:ive development of an invasion. Indeed, they are among
the principal factors which have prevented the extermination of
certain of the more important forest-tree species. These natural
enemies consist of parasites and predatory insects, which feed on
all stages of the barkbeetles, and birds, whiich feed on the adults
and young of the barkbeetles. Were it not for the fact that birds
also feed on the predatory and parasitic insect enemies of the bark-
beetles, and that such birds are limited in numbers. they might render
the great service that is so conirmmonly credited to them.
Insect diseases in the form of epidemics sometimes serve to bring
an invasion under complete control, and unfavorable climatic con-
ditions have been known to exterminate a species of Dendroctonus
beetles within an area of thousands of square miles.
Therefore, although under natural conditions successive genera-
tions of the older trees are killed by their insect enemies, these in
INSiEC DAMA.i'. IN 1111. \ %'MiNA.L VAH BKS.
turn are ciheckeld or repelled by i liaitral nit 1ii-. so tlll i l'i-iitiill-
of youlinger Itri'es ilkt, tire place of their iinc'-ti,'r-'. landl the forest as
such is perpetuated.
Naturital control the eu 'nei ',;e,'.-In the niitiiial pairk-. na-
tional fotrett, andl private foret-s.-. where the rivour -e., have a tiJmiiii'l-
cial value thli- nailural control of the iipcet di iciditur-s oni the
timlner is the Intist expensive and wa.,i-tlul. Ourl frieilid, the en-mit'.
of tht hwetlles, can not be ilpiril iidllrlip to ,lIritc fir lihl I-t
interests of the Federal or priv.it, awviiLr'. 'They viin. however, be
inade to render etlicieit service as thle allies f the owner in an igre--
.,ive warfare liy him agaiiit the invladlv.. InI this t'.ilirily they are
indiispen.,l1,i in the defenr.e ligaint renewed attark ;ill,1 in the niliin-
tenance of rontlitions which will insure the r'tiitiv protection of tit.
GENERAL METHODS OF CONTROL.
It is thrnuigh a knowledge ,f the hiabits and seasonal Ili-ti'ry of the
various spec'ie of depredatinig illtI -.il and the various t'iIplx fil-
tors operating for and aiiii t'l tiiiin, that I'li-rc i u (
tions either to reduct'e or eliiniiiiate the favorl)ih1l conditions for the
multiplication of the beetles or to proimoile and utilize the factr-'
that are unfavorable for their cxiilciiLce.
It is also thlroulhi a kiiowledt, of the chnaraci.i-viiir evidences of
their presence in tile living andl dliii_ trees that we are enabled to
give instructions to an 'xp let'n11i I',l ti bIer cruisert'. fri-i 1";il'lr. or1"
fire patrolman which will enable him readily to detect an infestation
and report upon its clihiracler and extent.
Experiment, witlh anil tlcliolll- irat ilu-. tif Dlfethlolc of control hIave
furnished up-to-,ihte information on the i -lliti.uI rtuoiireirrla. in
conducting at-ti'e critiir1 operatiin-., which enables us to adI iie the
most et'tnomnircal and vfl'ect'.a l method to be adopted for .i( h species
of beetle. each species of tree. andl earch locality where an iii f4.-tl illn
Therefore. if thle .symnptornI are accurately Ih-i r ilt-., and ifiir'ia.-
tion is furii.lhed1 .as to thle lo 'al facilliir.e for litili/iillg the inf't
timber or for treatment at direct expeniI-. .-pleilic recommIendations
for successful control call be nidou without an examination bv an
The presence in any national park of quailnittii-, of dying pine.
spruce, or Douglas fir that has not been "iii-ed I-v recent fire- is
evidence of thle presence and destructive wnrk ,f one nr more species
of the Dendroctonui. beetles. An examination of the 1ark of the
main trunks of some of the dying tres will i,1uaIly filniri-hr conclusive
evidence, for if the trees are infested the characteristic work in the
UNIVERSITY OF FLORIDA
3 1262 09216 6122
10 INSECT DAMAGE IN THE NATIC-.. -.
bark, as illustrated in the bulletins of the Bureau of Entomology, will
be easily recognized.
The next thing to do is to determine the extent of the infestation,
the kind of trees involved, and the facilities for disposing of the
timber by sale, free use, or direct expense. Then the superintendent
should report the facts to an expert and ask for advice and recom-
mendations. If he will then proceed without delay to dispose of the
infestation according to instructions given him, success in checking
or completely controlling the pest is almost certain to follow.
If, upon locating an infested area, it is found to extend beyond the
park boundary into adjacent privately owned timber or the national
forests, cooperation or at least concerted action is required, because
an important center of infestation is a menace to the living timber
within a radius of 10 to 20 miles.
If the timber of a national park is healthy and centers of infesta-
tion are found in adjacent forests within a radius of 10 to 20 miles,
the park superintendent should notify the owners. If, for any
reason, the owners can not dispose of the infestation the park officials
should help do it just as they would help in fighting a fire that
was threatening the park. In like manner the Federal and private
owners of healthy timber adjacent to a park should help dispose of
any extensive infestation in the park. because it may be more of a
common menace than a forest fire.
If this policy of cooperation for the general good is adopted and
the essential requirements for successful control are strictly adhered to
for a few years by the officials of the national parks, the national
forests, and the principal private owners, the damage to living
timber in the parks and on adjacent lands will be reduced to a mini-
mum, and ultimately thousands of dollars in commercial and Eesthetic
values will be saved for every dollar of public or private money
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