~?S'. i*+ ^ U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF ENTOMOLOGY CIRCULAR No. 143. * L. O. HOWARD. Kniomologiu *nd Chief of Burcu INSECT DAMAGE TO STANDING TIMBER IN THE NATIONAL PARKS. A. I). HOPKINS, In Charge of V jationM. ■ —Or. 1 1 WASHi: IK\I PBINTIKO OmC* : 1013 /.' / BEAU OF E V TO \tOL (> Q V. L. O. HOWABD, Entomologist and Chief of Bureau. ('. L. Maui att. Entomologist and Acting Chief in Absence of Chief. U. S. CLIFTON, linen tire Assistant. W. V. Tastit. Chief Clerk. F. H. Chittenden, in charge of truck crop and stored product insect investigations. A. 1). Hoi-kins, in charge of forest insect inrestigations. W. I>. HUNTER, in charge of southern field crop insect inrestigations. P. M. WEBSTER, in Charge of cereal and forage insect inrestigations. A. L. QuAlNTANCE, in charge of deciduous fruit insect investigations. E. F. Fiiijli.ii's. in charge of bee culture. D. M. Rogers, in charge of preventing spread of moths, field work. Koli.a P. CUBBIE, in charge of editorial work. Mabkl Polcord, in charge of library. Forest Insect Investigations. A. D. Hopkins, in charge. H. E. Burke, entomological assistant, in charge of Forest Insect Field Station S, Yreka, Cal. W. T). Edmonston, agent and expert, in charge of Forest Insect Field station G. Klamath Falls, Orcg. Josef Brunner. agent and expert, in charge of Forest insect Field station. I. Columbia Falls, Mont. E. B. Mason, entomological assistant, in charge of Forest Insect Field Station ?. Spartanburg. S. G. T. F. Snyder, agent and expert, engaged in investigations of insect damage to telegraph and telephone poles. J. L. Webb, entomological assistant, specialist on cerambgcid beetles and larva. S. A. RoHWER, agent and expert, specialist on sawflics i Tenthredinoidea). Mary F. Fatjnce, Mary C. Johnson, Maude Taylor, Elizabeth Ritchie, pre- parators. ii Circular No. 143. United States Department of Agriculture, BUREAU OK ENTOMOLOGY. L. O. HOWARD, KntomoloKin and Chief of Bureau. INSECT DAMAGE TO STANDING TIMIiKK IN TIM! NATIONAL PARKS. ' I'.y A. I >. IlorKis-. in t'luiiiji nf Forest Insect Investigations. CHARACTER OF THE DAMAGE. The damage by insects to the living trees of the forests and orna- mental grounds of the national parks consists of injuries to the foliage, branches, or the entire tree which mar or destroy their attractive, educational, and historic features and diminish <>r destroy their commercial \ alue. Throughout the forests of the Rocky Mountains and Pacific slope, including the national parks, a large percentage y the author at a eonferrnre of national park superintendent* held iinii.r the eosplcea of the Secretary of the Interior, September 11—12, mil. and Is embodied in Hie prow-dins* of the meeting Issued Ux the Interior Department 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 large 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 reconnaissance 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 year^. 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 as much dead as was ihen living, and every dead tree examined in the estimate showed evidence that it had been killed by insects. In the Black Hills National Forest of South 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 100,000 acres or more. These together with many other examples of extensive dying of timber have been investigated and found to be caused primarily by insects. Investigations have also demonstrated beyond question that a vast amount of timber is killed by insects every year within the forested areas of the Eocky 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 fires. 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 do 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 are 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 species. 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- lN.-it i DAMAG1 in Mil NATIONAL PABKS. 'A nal i \ | ic df foresl growth of thai region, i-> far greater than that rep resented by the commercial value of the timber; a- i- also tin- loss of notable veterans and giante of the different species. These old I'm' and old trees are at present one of the attractive and instructive fea (nil- 'if the timbered areas of some of the national parks, and if they ■re protected from their insect and other enemies thej will Ik 4 even more attractive features in coming centuries. Under present condi- tions, these "M trees of the virgin forest are in greater danger «»f being killed by insects than are the younger trees. Indeed, many of them have been killed within recent years. The three -.riant sugar pine- on the nail from Wawona to Glacier Point and the Yosemite Valley air examples. Two of them w< ■ lead and the other was dying when I -aw them in June. l'.'Ok and there was Conclusive evidence that their death W8S cau-ed l>\ the mountain pine beetle. The veteran Sugar pine, known a- " I'nele Tom," was being attacked at thai time by the Bame species of beetle, and I am informed that it died the following year. The loss of tl four Lriant> of the species i> irreparable. The Sequoias are supposed to he immune to the attack of insects, hut they are not. They are more resistant than other species, ami that i- one reason they have lived so long. However, each species ha- a barkbeetle enemy which, under favorable condition-, i- capable of killing the largest and finest specimens. I safi one of the large redwoods in the vicinity of Eureka, Cal., that had been killed by its barkbeetle enemy, and when in the Mariposa Grove, in 1904, I dis- covered the barkbeetle enemy of the big tree in the living hark of a storm-broken limb. THE PRINCIPAL DEPREDATORS. The mere mention of the name- of the thousands of species of in- sects, each of which causes some peculiar injury during the life of the different tree species, would occupy more -pace than i- allotted for this paper. Therefore we must consider the more important of those which are directly responsible for the death of the tree-. The little genus of Dendroctonus beetles, of tree-killing hectic-, is represented in the Rocky Mountain and Pacific Slope regions by a few species which are more destructive to the conifer- of western North America than all other forest insects combined. They are a constant menace to the pine, spruce, and Douglas fir of the national park-. They are certain to he present in every park in which there arc forests of their hosl tree-, and have doubtless caused far greater damage than the park officials have realized. The species, in the order of their destructiveness. are the mountain pine beetle, the western pine beetle, the Bngelmann spruce beetle, the 4 INSECT DAMAGE IX THK. NATIONAL PARKS. Jeffrey pine beetle, and the red turpentine beetle. All but the Jeffrey pine beetle of the 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 common to the 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 0.0S to 0.30 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- cavating 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 stage within a year and emerge from the bark to fly in search of new victims. Each species ha- its peculiar habits in the choice of host trees, methods of attack, and period of development. THK MOUNTAIN PINK BKKTKE. 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- trolled by felling the infested trees and 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 IN.-M i DAMAGI IN Till NATIONAL PABKB. 5 50 cents :> tree for the reipiired treatment, After an outbreak is under control the living timber can be easily protected from further depredations by giving prompt attention to the felling and barking of any clumps of dying trees found during May and June Rang or lire patrolmen can be instructed so thai they can il<> this and any- thing else thai is required t<> maintain control. Mil ¥ I - I M.N l-l \1 Bl I II I . The western pine beetle attacks the western yellow pine, the sugar pine, and the Jeffrey pine The hectic- fly in late June t<> Octol inclusive, and usually attack scattering individual trees, often select- ing the larger and older examples. The adults excavate winding egg galleries between the inner living bark and the wood and trans- form to the adult stage in the outer bark. The beetles begin («> fly and attack the tree- in dune and continue the attack until October or November. The first generation develops and emerges in August to November, and the second generation passes the winter in the tri that are killed by it in the summer and tall. The foliage of the infested trees begins bo lade and ftUm yellow in a few weeks after the trees are attacked by this hectic. The summer broods <>f the first generation leave the trees by the time the foliage is reddish htow n. hut the o\ erw intered broods do not emerge until the following May ami dune, in some cases Several months after 'he foliage is brown. Thi> Specie: is next in importance to the mountain pine beetle .1 destructive enemy of the pine, and the two special often combine in their attack. In this combined attack the wesiera pirn hectic is a secondary enemy of the trees Decease it follow- the attack of the other species. When it is the primary enemy it i- responsible for the death of a few BCattering tree- each year throughout the foiv-t. which results in the accumulation of dead timber. In the aggre- gate, tlii- accumulative loss i- very extensive, involving, as it does, the largest and best trees. The insect can Iw controlled and the living timber protected from by felling the infested trees during the period between the 1st of October and the Lai of June and removing the hark- from the main trunks and burning it. It is necessary to hum the hark because the broods of this species transform in the outer hark. They are not destroyed by -imply exposing the inner hark, a- i- the ca-c with the mountain pine hectic. Mil -1 KI KKKV lMNh CI I 111. The characteristic habits of the Jeffrey pine hectic are similar to those of the mountain pine beetle, and therefore it requires the same treatment. 6 INSECT DAMAGE IN THE NATIONAL PARKS. THE DOUGLAS FIR BEETLE. The Douglas fir beetle attacks the Douglas fir, the big-cone spruce, and the western larch. The 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 characteristics 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 b< j gin> to die in the fall. It is very destructive to the Douglas fir throughout the Rocky Mountain 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 burning. THE RED 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 trunk-. 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 rareh 7 kills a tree, but is the cause of a large percentage of the basal wounds known as "cat faces" 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 trees and the 1 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 ;i- their presence is indicated by masses of exuding resin mixed with reddish boring dust. Wherever there are continued lumbering operations the red turpen- tine beetle confines its attack to the 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- age to the living timber for a year or two after. In combating the other beetles in the national parks, care should be taken to remove the bark from the stumps whenever they are found to be infested with this pest. THE ENGELMANN SPRUCE BEETLE. The Engehnann spruce beetle attacks the Engelmann spruce, blue spruce, and any other species of spruce found within its range, but INSKCI DAMAG1 IN THE NATIONAL PA1 7 does not attack the pine. Douglas fir, or balsam fir. I( flies in the period from June to August and attacks the bark of the main trunks of the ulilcr or matured tree-, h- habits are Bimilar to those of the mountain pine beetle, except that it flies earlier in the spring. When the trees begin to die the needles fade to a pale green and fall before they change to yellow or brown, but the bare tw igs present a grayish- brown appearance. The infested trees are easily Located in the fall ;iikI early Bpring by the fallen needles and the bare twigs of the tops. This species occurs from British Columbia to Mexico and at times is rery destructive to the Engelmann spruce forest-. It can l>e controlled by felling the infested trees and removing the bark from the main trunk- during the period beginning with the 1st of October and ending by the middle to last of May. I ill: r.i.\< K Mil. is i;i I mi. The Black Hills beetle is by far the most destructive insect enemy of the pine of the central and southern Rocky Mountain- and the Black Hills of South Dakota. It- habits are similar to those of the mountain pine beetle, and the -ame method- are adopted for its control. FAVORABLE CONDITIONS FOR THE BEETLES. There are certain conditions in the administered a- well as in the natural forests which contribute to the multiplication and destructive \\ ork of these 1 'end rod onus heet I es. One of the most favorable con- ditions is an extensive forest of matured and old trees of pine or b] nice, because in the beginning of an invasion such trees are more often the lirst to be attacked and killed. Trees in such a forest injured by lightning or storms often form center- of infestation in which the beetles increase to sufficient numbers to enable them to kill a few trees, and then the invasion i- started, year after year increasing in force until a large percentage or all of the old timber is killed. The hectics then attack the young trees and often waste their energies on saplings, in which the broods fail to develop. Drought. — It is a common belief that severe droughts weaken the and tin;- contribute to favorable condition- for the attack of the beetles. We have made a \ery thorough investigation of this sub- ject and are led to conclude that exceptionally dry seasons are more unfavorable for the development of the beetles than are moderately humid one-, and that, therefore, droughts do not contribute to their multiplication. Forest fires. — Forest fires contribute, to a limited extent, to the multiplication of certain species which breed in fire-scorched tree-. but as a rule forest tire- kill more beetles than they protect. 8 lXSKCT L).\M.u;i- tn the national pakks. Coinmi rc'iiil cutting. — Commercial cutting of timber may contrib- ute to the multiplication of certain species which breed in the stump.- and tops, but if the cutting is continuous the insects confine then- 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 wa-te 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 d} - ing trees. In other words, systematic forest management based on a knowl- edge of the principles of silviculture and forest entomology will soon present conditions so unfavorable for the Dendroctonus beetles that thev can no longer exist as agents of destruction and waste. The natural enemies of the beetles serve as a repelling force against the progressive development of an invasion. Indeed, they are among the principal factors which have prevented the extermination of certain of the more important forost-tree species. These natural enemies consist of parasites and predatory insects, which feed on all stages of the barkbeetles, and birds, which 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, the} 7 might render the great service that is so commonly 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 IN SIC I l>\\|\t.l IN I II I \ M ' 1 • i N Hi l'\. 9 turn em checked or repelled by natural means, bo that generations of younger trees take tin- place of their anc tnd the feces! m such l- perpetuated. Natural iniifrn/ tkt In thfl national park-, na tional forests, and private foreete where the n icommer- cial vain* this natural eontrol of the insect depredators on 1 1 1 * - timber is the mod expensive and wasteful Our friends, the enemies of the beetles, can not be depended upon to operate for the besl interests of the Federal or private owner. They can, however, be made to render efficient service as tin' allies of the oi osr in an aggres- sive warfare by him againsl the invaders In 1 1 * i — - capacity they are indispensable in the defense against renewed attacks and in 1 1 1 * - main tenaace of conditions which will insure the future protection of the living timber. GENERAL METHODS OF CONTROL. It is through a knowledge of the habits and seasonal history of the various species of depredating insects, and the various complex fac- tors operating Cor and against them, thai forest entomologists arc enabled to advise methods of procedure in practical control opera- tions either to reduce or eliminate the favorable conditions for the multiplication of the beetles or to promote and utilize the factors that are unfavorable for their existence. It is also through a knowledge of the characteristic evidences of their preeence in the living and dying trees that we are enabled to give instructions to an experienced timber cruiser, forest ranger, or fire patrolman which will enable him readily to detect an infestation and report upon its character and extent. Experiments with and demonstrations of methods of control have furnished up-to-date information on the essential requirements in conducting active control operation-, which enables ns to advise the most economical and effectual method to be adopted for each species of beetle, each species of tree, and each locality where an infestation prevails. Therefore, if the symptoms are accurately described and informa- tion is furnished as to the local facilities for utilizing the infested timber or for treatment at direct expense, specific recommendation-, successful control can he made without an examination by an expert The presence in any national park of quantities of dying pine. spruce, or Douglas fir that has not been caused by recent fir evidence of the presence and destructive work of one or more species of the Dendroctonus beetles. An examination of the bark of the main trunks of some of the dying tree- will usually furnish conclusive evidence, for if the trees are infested the characteristic work in the UNIVERSITY OF FLORIDA 3 1262 09216 6122 10 INSECT DAMAGE IX THE XATIC . .„. 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 exjjense. 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 aesthetic values will be saved for every dollar of public or private money expended. fTHIS PUBLICATION may be pro- A cured from the Superintendent of Documents, Government Printing Office Washington, D. C, at 5 cents per copy Price furnished on application for !o Is o f 1 00 or more