Pine Bark Adelgid Fact Sheet

Fact Sheets > Insect Fact Sheets > Pine Bark Adelgid

  The Pine Bark Adelgid, Pineus strobi (Hartig), native to Europe but one of the most commonly reported insect pests of pines in America, feeds on tree trunks by sucking sap from the phloem tissues. It can be problematic for small nursery stock, but if trees are healthy, permanent damage should not result.

Plants Attacked

The pine bark adelgid is found principally on eastern white pine (Pinus strobus) but occasionally attacks other pines such as the Scotch (Pinus sylvestris), ponderosa (Pinus ponderosa), jack (Pinus banksiana), pitch (Pinus rigida) and Austrian (Pinus nigra) pine.

Insect Identification

The eggs are a milky to light yellow-brown color and hidden under a white woolly mass secreted by adult females. The immature adelgids resemble the adult, and are initially yellow but darken with age. The adult is small (about 1/32 inch), dark purple, tear-drop shaped with short legs, and covered by the white woolly secretions.

Pine bark adelgid eggs	Pine bark adelgids on trunk of eastern white pine

Life History

Winter	This pest usually over-winters as immature females on the bark and branches.
Spring	In early spring the female matures and lays her eggs in a woolly mass. Winged and wingless forms hatch from the eggs. The winged forms have the ability to migrate to different hosts. Wind and birds also account for distribution of the insect.
Summer	The reproduction cycle continues, since there are five or more generations each year with adults, nymphs and crawlers present throughout the summer.

Damage Symptoms

Damage to older trees is purely aesthetic, but newly planted trees can be seriously injured by the pine bark adelgid, with heavy infestations stunting plant growth. The white woolly filaments, secreted by the insects for their protection, can give the appearance that the host is white-washed or snow covered. Pine bark adelgids also secrete honeydew, which can lead to the presence of sooty mold.

Pine bark adelgid infestation	White waxy exudate covering pine bark adelgid nymphs

 

Management Options

Biological	Lady beetles, dustywings and hoverflies all feed on pine bark adelgid. If beneficial predators are present, the use of "predator friendly" insecticides, such as insecticidal soap or horticultural oils, should be used. Pest populations should be closely monitored.
Chemical	Dormant oil sprays and insecticides are effective in killing over-wintering nymphs if applied in the fall or spring before nymphs mature and lay eggs. Control Measures for Pine Bark Adelgid

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Authored by:
Katherine Mazzey, Penn State Extension Program Assistant
Michael Masiuk, Extension Agent, Penn State University - Allegheny County

Sources:
Center for Integrated Pest Management. North Carolina State University. Pine Bark Adelgid http://ipm.ncsu.edu/AG189/html/Pine_Bark_Adelgid.HTML

Collins, J. & Townsend L. (1994). Common Sap Feeding Pine Pests. University of Kentucky Cooperative Extension Service. http://www.uky.edu/Agriculture/Entomology/entfacts/trees/ef412.htm

Baker, J.R. (2000).Pine Bark Adelgid. North Carolina Cooperative Extension Service. http://www.ces.ncsu.edu/depts/ent/notes/O&T/trees/note62/note62.html

Hahn, J. & Kyhl J. F. (2002). Wooly Aphids on Trees and Shrubs. University of Minnesota Extension Service. http://www.extension.umn.edu/projects/yardandgarden/ygbriefs/e453woollyaphid.html

Hoover, G.A. (2000). Woody Ornamental Insect, Mite, and Disease Management. Penn State College of Agricultural Sciences. pp.45. http://woodypestguide.cas.psu.edu/Insects.html

Johnson, W.T. & Lyon, H.H. (1976). Insects That Feed On Trees and Shrubs, pp.76. Comstock Publishing Associates. Cornell University Press.

Salom, S.M. (1996). Pine Bark Adelgid. Virginia Polytechnic Institute & State University. Virginia Cooperative Extension. http://www.ext.vt.edu/departments/entomology/factsheets/pibadelg.html

Shetlar, D. J. Pine Bark Adelgid. Ohio State University Fact Sheet. http://bugs.osu.edu/~bugdoc/Shetlar/factsheet/christmasstree/pine_bark_adelgid.htm