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
Order	Coleoptera
Suborder	Polyphaga
Infraorder	Cucujiformia
Superfamily	Curculionoidea
Family	Curculionidae
Subfamily	Scolytinae
Tribe	Hylurgini
Genus	Dendroctonus

Scientific Name

Dendroctonus simplex

Common Name

eastern larch beetle

Orientation to Pest

Eastern larch beetle, Dendroctonus simplex (LeConte), is a native North American bark beetle whose only important host is eastern larch, Larix larcina (Du Roi ) K. Koch. The species overwinters as larvae or adults in galleries. Eggs are laid in groups along an egg gallery made by the female in the inner bark and outer sapwood. Larval tunnels are short and occur in the inner bark. There are up to three generations per year. Before the 1970s, this bark beetle was only known to attack dying or recently felled trees. Since then, however, a series of large outbreaks in healthy stands have occurred in both Canada and the United States. Some of these bark beetle outbreaks followed outbreaks of the defoliating larch sawfly Pristiphora erichsonii (Hartig), which had produced many stressed or dying larch trees. While the exact causes of these population fluctuations are unknown, some authors have attributed outbreaks to the maturing of larch stands over large areas, which lowers host resistance.

Hosts Commonly Attacked

Hosts of this species are eastern larch (L. larcina), and occasionally red spruce (Picea rubens Sargent).

Distribution

This bark beetle is found in the USA from New England south to West Virginia, and west to Minnesota. It is also found in Alaska and in Canada from the Atlantic to the Pacific coast.

Biological Control Agents

Eastern larch beetle has a large complex of natural enemies that have been studied in a number of locations (see Van Driesche et al. 1996 for a review). Some of the natural enemies reported include the dolichopodid fly Medetera gaspensis Bickel and the rhizophagid beetle Rhizophagus dimidiatus Mannerheim (both predators) and the parasitoids Spathius canadensis Ashmead (Braconidae) and Rhopalicus tutela (Walker) and Roptrocerus xylophagorum (Ratzeburg).

Web Links

Articles

Duncan, B. 1987. An illustrated guide to the identification and distribution of the species of Dendroctonus Erichson (Coleoptera: Scolytidae) in British Columbia. Journal of the Entomological Society of British Columbia 84: 101-112.

Langor, D. W. and A. G. Raske. 1988. Annotated bibliography of the eastern larch beetle, Dendroctonus simplex LeConte (Coleoptera: Scolytidae).Information Report - Newfoundland Forestry Centre, Forestry Canada (N-X-266), 1988, 38 pp.

Langor, D. W. and A. G. Raske. 1988. Mortality factors and life tables of the eastern larch beetle, Dendroctonus simplex (Coleoptera: Scolytidae), in Newfoundland. Environmental Entomology 17: 959-963.

Langor, D. W. and A. G. A. Raske. 1989. A history of the eastern larch beetle, Dendroctonus simplex (Coleoptera: Scolytidae), in North America. Great Lakes Entomologist 22: 139-154.

Van Driesche, R. G., S. Healy, and R. C. Reardon. 1996. Biological control of arthropod pests of the northeastern and north central forests in the United States: a review and recommendations. USDA FS, FHTET-96-19, Morgantown, West Virginia, pp. 58-59 http://www.forestpestbiocontrol.info/fact_sheets/documents/arthropodpestsnortheastern_northcentral.pdf