May 2004 Forest Health and State and Private Forestry Organizations

4.12 WEB July 2010 Management Guide for

By Liz Hebertson Pinyon Engraver Beetle US Forest Service Ips confusus LeConte (Coleoptera: Scolytidae)

Hosts: Topics The pinyon engraver beetle  Colorado pinyon Damage 1 is the most important insect mortality agent in pinyon  Singleleaf pinyon Life History 2 in Regions 1 and 4.  Other pinyon species Identification 2

Management 3 Stand Composition 4 Damage Timing of 4 Treatment In healthy pinyon-juniper beetles. Moisture stress has been woodlands, endemic levels of the found to increase soluble Other Reading 5 pinyon engraver work in association nitrogenous compounds and sugars Field Guide with other insects and diseases to in living cells of trees. Both of kill weakened and stressed trees. these substances are important for Management Guide Tree mortality thins the forest the development of beetles. Pinyon Index reducing competition for light, engraver activity is often associated water, and nutrients. Population with black stain root disease levels may build when ample host (Leptographium wageneri). The material is available. This material beetle also favors pinyons with Key Points may consist of green pruned heavy dwar f mistletoe  Drought may branches and recently broken, (Arceuthobium divaricatum) increase a tree’s uprooted, or downed trees. infections. susceptibility to Outbreaks of pinyon engravers may Tree damage occurs when adult engraver beetle continue for one to several years beetles colonize and reproduce in attack. killing large groups of trees over the the conductive tissues of suitable  Egg galleries landscape. host trees. Conductive tissues have forked or Drought, disease, or injuries by transport water and nutrients star-shaped other insects are often important in throughout the tree. patterns. weakening trees, thus increasing the potential for successful engraver  Beetles introduce attacks. Moisture stress may a ‘blue stain’ Pinyon engraver fungus that plugs increase tree susceptibility in two populations may up conductive ways. The first way is by reducing build when tissues. the production of sap. Vigorous trees can produce enough sap to ample host  Adults overwinter push or ‘pitch’ attacking beetles out material is in groups at the available. base of infested of entrance holes. Beetles often trees. become trapped in the sap and die. The second way is by increasing the nutritional quality of the tree for the Page 2 Back to menu Pinyon Engraver Beetle 4.12 Life History Adult beetles generally resulting in a forked or star-shaped overwinter in groups at the base of gallery pattern. Unlike Dendroctonus infested trees. Adults emerge in the beetles, pinyon engravers do not spring to infest suitable host material pack their galleries with frass and often re-attacking uninfested travel freely along the entire gallery The life cycle portions of the same tree or attacking length. Females lay eggs singly of pinyon another susceptible host tree. In Utah along both gallery walls. These eggs engraver and Nevada, pinyon engravers hatch into small larvae and create beetles last normally begin flight in mid-April. A larval galleries extending from 6-8 male beetle locates and attacks host perpendicular to the egg gallery. weeks with up material emitting a pheromone that Larvae eventually pupate and to 5 attracts females and other males. transform into new adults. The life generations in The male mates with one or more cycle of pinyon engraver beetles one season. females in a nuptial chamber generally lasts from 6 - 8 weeks with constructed within the tree phloem. up to 5 generations produced in one The females construct galleries to lay season depending on climate and their eggs. These egg galleries elevation. With multiple generations initially radiate outward from the produced every year infested trees nuptial chamber then generally may contain beetles of various life follow the grain of the wood stages. Identification Adult beetles are cylindrical, orange/red within a few days or ranging in size from about three to weeks. Before long, the needles seven millimeters long. They are begin to fall. Successfully attacked reddish-brown to black in color and trees will also have red or orange often shiny. As with other Ips boring dust (frass) in bark crevices species, pinyon engraver beetles and/or around the base of the tree. have a pronounced depression at the Boring dust is produced when beetle rear end of their wing covers. Five chews through the bark. Small, spines occur along the margins of inconspicuous tubes of pitch each side of this depression. containing boring dust may also be Foliar symptoms provide initial visible on the bark surface around evidence of pinyon engraver beetle entrance holes. attack. Pinyon needles on branches or trees killed by the beetle will generally turn yellow (fade) to

Pitch tubes on pinyon pine. Photo Adult engraver beetle on dime. courtesy of USDA Region 3 FHP Page 3 Back to menu Pinyon Engraver Beetle 4.12

Water stress, diseases and the presence of other insects can increase a tree’s susceptibility to pinyon engraver attack.

Susceptibility:

1. Characteristic. The most susceptible trees are relatively old with average root collar diameters (drc) between seven and eleven inches. 2. Climate. During intense drought years, pinyon pines may be susceptible to attack even in stands with low densities and small tree diameters (2 inches drc) . 3. Density The probability of beetle attack also increases with increasing pinyon density even when pinyon represents a minor portion of the stand (Negron and Wilson 2003).

Management High value trees such as those in Thinning offers the best long- recreation sites may be sprayed with term management strategy for the a registered insecticide to protect pinyon engraver beetle. To maximize them from attack. Insecticides with effectiveness, thin the pinyon the active ingredient Carbaryl are component to an SDI of 20 or less quite effective and several brand (~6% of maximum SDI; 360 for pure names are registered engraver stands (pinyon or juniper) and 415 beetles. These sprays, when applied for mixed stands). Where stands are as a 2% solution, provide protection composed of mixed pinyon and from attacking engraver beetles for juniper, a total SDI of 24 may be 16-18 months. The insecticide must appropriate and will approximate the saturate all sides of the trunk and same competitive conditions. Table larger branches (≥ 1 inch in 1 shows traditional measures of diameter). If any portion of the trunk stand density for an SDI of 24 for High value or susceptible branches is missed, given size classes. Multi-aged/sized trees such as then beetles can successfully attack stands should have the total SDI those in the non-treated area. apportioned among size classes recreation (Table 2). sites may be sprayed with a Table 1. registered TPA, BA, and Spacing Between Trees based on SDI and Diameter insecticide to (Stand SDI = 24 or 5.6% of maximum SDI) protect them SDI DRC TPA BA Spacing from attack. 24 6 54 10.7 28.3 24 8 34 12.0 35.6 24 10 24 13.1 42.6 24 12 18 14.1 49.3 24 14 14 15.0 55.8 24 16 11 15.8 62.0 24 18 9 16.6 68.2 24 20 8 17.3 74.2 24 22 7 17.9 80.1 Page 4 Back to menu Pinyon Engraver Beetle 4.12

Table 2. Target After-Treatment Stand (at 5.6% of max SDI) Size Class SDI TPA BA Spacing Regen (<3”) 6.5 45 2.2 31.2 Small (3-6”) 6.5 15 2.9 54.4 Mid (6-9”) 6.5 8 3.4 75.2 Large (>9”) 6.5 14 15.0 55.8 Total 26 82 23.5 --

not be favored for leave trees over Thinning Various factors should be taken offers the into account in the selection of trees adjacent uninfected and otherwise best long- to retain on the site (“leave trees”). healthy trees. Pinyon engraver term Damaging agents, such as disease or beetles prefer trees with somewhat management physical damage (including logging reduced crown ratios. Pinyon leave strategy for damage), can weaken and stress trees should be those with the higher the pinyon trees, making them more susceptible percentage of crown-to-height ratio. engraver to pinyon engraver. Leave trees The beetles also prefer larger beetle. should be those that appear the diameter pinyon trees, thus it may be healthiest trees with the least desirable to retain older juniper damage. If dwarf mistletoe (a “legacy” trees and remove any older/ parasitic species) is present on larger pinyon trees that show signs of individual trees, these trees should declining vigor.

Stand Composition Stand susceptibility to pinyon desirable to maintain a good mix of engravers is also influenced by stand species. Additionally, treatments composition, and those stands with a may vary by size of pinyon leave higher percentage of pinyon-to- trees and percentage of pinyon-to- juniper tend to be more susceptible juniper leave trees. to beetle-caused mortality. Thus it is

Timing of Treatment Timing of implementation and debris can attract beetles during the treatment of pinyon slash can be beetles’ flight periods. Pinyon critical factors when pinyon engraver engravers cannot colonize chips but beetles are present in the general may attack nearby pinyon trees. If area. Green pinyon slash can serve chips or slash are to be left on the as an attractant to beetles. Beetles site, then treatment is best done in can colonize slash during the spring late fall, allowing the winter months and summer months and maturing for material to dry and become less beetles can emerge from this slash attractive to beetles. Larger green seeking new hosts, which will tend pinyon material that is not chipped to be the nearest available suitable should be removed or disposed of pinyon trees. Even chipped pinyon before the next beetle flight (March). Page 5 Back to menu Pinyon Engraver Beetle 4.12

If green pinyon material greater than fewer pinyon or to leave more 3 inches in diameter can be removed pinyon, realizing that many of these from the site within four to six weeks trees may be subsequently killed by of cutting, then operations may be beetle attack. If retention of pinyon done at any time without risking trees on the site is of prime concern, increasing the incidence of beetles. If it may be best to delay thinning Forest Health and neither can be practically pinyon stands when populations are State and Private accomplished, then mitigation for high in the drainage where the Forestry increased beetle activity may be treatment is to take place. Organizations either to leave more junipers and

Assistance on State And Private Lands Other Reading Montana: (406) 542-4300 Cain R, Parker D, Ward C. 1995. pests in . Cooperative publication of the New Mexico Department of Agriculture, New Mexico Idaho: (208) 769-1525 Department of State Forestry, USDA Forest Service, and Cooperative

Utah: (801) 538-5211 Extension Service. Albuquerque, NM: USDA Forest Service

Nevada: (775) 684-2513 Furniss RL, Carolin VM. 1977. Western Forest Insects. USDA Forest Service, Miscellaneous Publication No. 1339. Washington, DC: USDA Forest Wyoming: (307) 777-5699 Service.

Assistance on Hawksworth FG, Wiens D. 1996. Dwarf mistletoes: biology, pathology, and Federal Lands systematics. Agricultural Handbook 709. Washington, DC: USDA Forest US Forest Service Service. Region One Missoula: (406) 329-3605 Hessburg PF, Goheen DJ, Bega RV. 1995. Black stain root disease of . Coeur d’Alene: (208 765- Forest Insect and Disease Leaflet 145. Washington, DC: USDA Forest 7342 Service.

US Forest Service Mathiasen R. Beatty JS, Pronos J. 2002. Pinyon pine dwarf mistletoe. Forest Insect Region Four Ogden: (801) 476-9720 and Disease Leaflet 174. Washington, DC: USDA Forest Service. Boise: (208) 373-4227 Page, D. 2005. Preliminary thinning guidelines for pinyon-juniper ecosystems. Bureau of Land Management, Southwest Utah Zone, Cedar City, UT.

Negron, J. and J.L. Wilson. 2003. Attributes associated with probability of infestation by the Pinyon ips, Ips confuses, (Coleoptera; Scolytidae) in pinyon pine, . Western North American Naturalist 63(4): 440- 451.

Rogers TJ. 1993. Insect and disease associates of the pinyon-juniper woodlands. In Preceedings: Managing pinyon-juniper ecosystems for sustainability and social needs. Comps Aldon EF, Shaw DW, 124-125. USDA Forest Service, Rocky Mountain Research Station, General Technical Report RM -236. Fort Collins, CO.

Wilson, J.L. and B.M. Tkacz. 1992. Pinyon ips outbreak in pinyon juniper woodlands in northern Arizona: a case study. Pages 187-190 in Symposium on Ecology and Management of Oak and Associated Woodlands: Perspectives in the Southwestern United States and Northern Mexico. Sierra Vista, AZ. April 27-30, 1992.

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