This insect pest attacks blue, Engelmann, Norway, Sitka, and white spruce in Washington. Biology, description, and cultural control are discussed. 2 pages

Antonelli, Arthur

Mayer, D.

Ophardt, Marianne

Washington State University  institutional repository

Extension Bulletin 1089SPRUCE NEEDLE MINERThe spruce needle miner, Endothenia albolineana,is a native insect of Washington. It is found through-out North America as a pest of spruce trees. This in-sect has become more common in Washington dur-ing the past few years. Even light infestations of thispest can make ornamental spruces look unsightly.DamageThe spruce needle miner attacks blue, Engelmann,Norway, Sitka and white spruce, and is more fre-quently a pest in eastern rather than in western Wash-ington.Spruce needle miner damage. Note larval emergence hole (arrow) at base of dead needle at top. The presence ofneedles with these holes is a diagnostic indication of needle miner even when the insect is gone.COOPERATIVE EXTENSIONFeeding by spruce needle miner larvae kills theneedles and may be especially injurious to ornamen-tal trees. The entire crown of small trees may bekilled. On larger trees, infestations are usually foundon the lower branches and near the inner part of thetree. This needle miner seldom kills large trees, butcan cause unsightly damage.Biology and DescriptionAdults of this insect are small, brown moths with awingspread of about 1/2 inch (12 mm). The frontwings have three irregular, grayish white bands. Thehind wings are brown with a lighter colored fringe.Spheroid eggs are very small and pale green. Thelarvae, or caterpillars, when full grown, are about1/3 inch (8 mm) long and reddish brown, green, orgreenish brown with shiny yellowish brown heads.Adults appear in May and June. Females lay eggs ingroups of six or seven, shingle fashion, on the needles.After hatching, the larvae tunnel into needles, enter-ing at the needle base. Mined needles do not containany frass (insect excrement). A single larva may feedin more than one needle. As the larva grows in size,it cuts off the mined needles and spins silk strands totie the needles and frass together into a webbed“nest.” This is what makes infested trees look un-sightly (photo). Larvae hibernate in the hollowedneedles within the webbed “nests.” In March, theyresume feeding and complete their growth. Pupation(pre-adult resting stage) occurs in April after the larvamakes a silken cocoon in the webbing. One genera-tion occurs per year.ControlBecause the spruce needle miner rarely kills largetrees, the problem during light infestation is largelyone of unsightliness. Heavily infested branch tips canbe pruned and burned. Washing the webs from thetrees with a strong stream of water in March is aneffective control. Wash all needles and webs to theground, then collect and burn them. To date, no bio-logical control agents for this pest have been found.Chemical control may be necessary to reduce dam-age. A number of registered products are availablefor control of this pest. Since registrations changefrom year to year, we direct our clients to contact theWSU Master Gardener clinics or County Extensionagents to find out from the Pacific Northwest InsectControl Handbook what is currently registered. Thishandbook is revised annually and provides the mostcurrent legal recommendations available. Timing iscritical and sprays should be applied in late May toearly June or when new tree growth is fully expandedand adult moths are present.College of Agriculture and Home EconomicsUse pesticides with care. Apply them only to plants, animals or sites listed on the label. When mixing and applying pesticides, followall label precautions to protect yourself and others around you. It is a violation of the law to disregard label directions. If pesticides arespilled on skin or clothing, remove clothing and wash skin thoroughly. Store pesticides in their original containers and keep them outof the reach of children, pets, and livestock.By Daniel F. Mayer, Ph.D., Washington State University Cooperative Extension entomologist, WSU Prosser; Marianne C. Ophardt,MS, WSU Cooperative Extension agent, Kennewick; and Arthur L. Antonelli, Ph.D., WSU Cooperative Extension entomologist,WSU Puyallup. Issued by Washington State University Cooperative Extension and the U.S. Department of Agriculture in furtheranceof the Acts of May 8 and June 30, 1914. Cooperative Extension programs and policies are consistent with federal and state laws andregulations on nondiscrimination regarding race, color, gender, national origin, religion, age, disability, and sexual orientation. Evi-dence of noncompliance may be reported through your local Cooperative Extension office. Revised October 1996. Subject codes 255,352. A. EB1089

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Spruce Needle Miner

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Spruce Needle Miner

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