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Balsam woolly adelgid eggs. Photo by Scott Tunnock, USDA Forest Service, Bugwood.org. -
Adult Balsam woolly adelgids are small and hard to spot. Photo by Christine Buhl, Oregon Department of Forestry, Bugwood.org. -
Swollen, deformed branches caused by damage from Balsam woolly adelgids. Photo by Dawn Dailey O'Brien, Cornell University, Bugwood.org. -
Swelling (gouting) around buds and branch nodes caused by balsam woolly adelgids. Photo by Ladd Livingston, Idaho Department of Lands, Bugwood.org. -
Infestation of balsam woolly adelgid on tree trunk. Photo by Jerald E. Dewey, USDA Forest Service, Bugwood.org. -
Tree mortality from balsam woolly adelgid. Photo by Leslie J. Mehrhoff, University of Connecticut, Bugwood.org.
Scientific name: Adelges piceae Ratzeburg
Native range: Europe
At Risk
All species of fir (Abies spp.) are potential hosts for balsam woolly adelgid. In particular, Fraser and balsam fir can be seriously affected. As a result, Christmas tree growers are at particular risk from this insect.
Distribution
Balsam woolly adelgid was introduced into eastern Canada and the Northeastern U.S. sometime in the early 1900s and was discovered in the Pacific Northwest in 1929. Balsam woolly adelgid can now be found in those areas as well as small areas of California and the Appalachian Mountains.
Biology
Adelgids are sedentary for most of their life cycle. Eggs hatch into crawlers, the only mobile life stage, and they disperse short distances by wind or animal movement. The crawlers settle on bark, insert their straw-like mouthparts, and begin feeding on sap, eventually maturing into adult females. No males occur in North America, meaning that all reproduction is through parthenogenesis. As the adelgids feed, they produce a woolly covering of wax. Mature females lay eggs under the woolly covering. There can be two or three overlapping generations per year depending on latitude and elevation. Adelgids overwinter as immature nymphs.
Identification
Balsam woolly adelgids themselves are small and difficult to see. A white woolly substance is produced by adults as they feed, usually on the trunk below where branches emerge. Wool often remains on the bark throughout the year. Symptoms of balsam woolly adelgid feeding is more likely to be noticed. A flat top or weak terminal that is slanted, swollen twigs that drop their needles (referred to as gouting), dead shoots or branches and wilted appearance of shoots are common symptoms.
Regulatory Status: Regulated
There are no federal, state or local regulations related to balsam woolly adelgid in Minnesota. However, the State of Michigan regulates the import of materials that could harbor balsam woolly adelgid from infested states. State regulations may be implemented if balsam woolly adelgid were found in Minnesota.
What Can I Do?
Buy stock only from reputable nurseries and do not transport wild trees from infested areas. Contact the Minnesota Department of Agriculture via Report a Pest if you suspect you have found balsam woolly adelgid.
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