Authors: Van Driesche, R.G., J.H. LaForest, C.T. Bargeron, R.C. Reardon, and M. Herlihy. 2012. Forest Pest Insects in North America: a Photographic Guide. USDA Forest Service. Forest Health Technology Enterprise Team. Morgantown, WV. FHTET-2012-02.

Taxonomy

Domain	Eukarya
Kingdom	Animalia
Phylum	Arthropoda
Subphylum	Hexapoda
Class	Insecta
Subclass	Pterygota
Infraclass	Neoptera
Superorder	Paraneoptera
Order	Hemiptera
Suborder	Sternorrhyncha
Infraorder	Aphidomorpha
Superfamily	Adelgoidea
Family	Adelgidae
Genus	Adelges
Subgenus	Sacchiphantes

Scientific Name

Adelges abietis

Common Name

eastern spruce gall adelgid

Orientation to Pest

Eastern spruce gall adelgid, Adelges abietis (L.), is a pest of the introduced Norway spruce (Picea abies [L.]) and of various native North American spruces, especially white spruce (Picea glauca [Moench]). It is an invasive species believed to be of European origin. Damage is caused by induction of galls on new growth. Adults, which are wingless, deposit their eggs near buds in spring and newly developing needles are stimulated by developing nymphs to become enlarged, fusing into a pineapple-shaped gall, within which nymphs mature. In summer and early fall, the chambers of the gall open and nymphs emerge and transform themselves into winged adults, which lay eggs. These hatch and nymphs overwinter at the base of needles and buds. In spring, when the gall is newly formed, it is light green in color, but after it matures and insects emerge, it dries and turns brown, remaining on the branch as a sign of earlier infestation. Damage results from twig deaths induced by galls, which makes the tree misshapen. Heavily infested trees may die.

Hosts Commonly Attacked

This adelgid feeds on black (Picea mariana (Mill.) Britton, Sterns & Poggenburg), Norway (Picea abies), white (Picea glauca) spruces.

Distribution in the USA

Eastern spruce gall adelgid occurs widely in the eastern United States from Maine to Tennessee and Illinois, as well as in northern Minnesota, Wisconsin, and Michigan, and adjacent parts of Canada. Localized infestations also occur in parts of Montana, Wyoming, and South Dakota. A map of this distribution is available at http://www.fs.fed.us/nrs/tools/afpe/maps/ESGA.pdf.

Biological Control Agents

Because damage from this species is not severe, natural enemies have not been imported from the pest's native range into North America for control. Predacious flies have been observed feeding on this adelgid in Europe (the syphid Cnemodon sp.) and, in Turkey, Leucopis species have been recorded feeding on related adelgids, but in general little is known about the natural enemies of this species.

Web Links

Articles

Flaherty, L., D. Quiring, and J. A. Kershaw, Jr. 2010. Post-gall induction performance of Adelges abietis (L.) (Homoptera: Adelgidae) is influenced by clone, shoot length, and density of colonising gallicolae. Ecological Entomology 35: 9-15.