Dendroctonus pseudotsugae

Dendroctonus pseudotsugae, the Douglas-fir beetle, is a species of bark beetle found in western North America. Three subspecies exist that correspond to the subspecies of Douglas-fir. The beetles also infest downed Larch trees.[1] Outbreaks often occur in conjunction with drought, root rot diseases, overcrowding, damage by insects that damage foliage, and environmental disturbance. This insect is part of the western forest ecosystem, playing a role in thinning weak trees in a stand.[2]

Douglas fir beetle
Scientific classification
Kingdom:
Animalia
Phylum:
Arthropoda
Class:
Insecta
Order:
Coleoptera
Family:
Curculionidae
Subfamily:
Scolytinae
Genus:
Dendroctonus
Species:
D. pseudotsugae
Binomial name
Dendroctonus pseudotsugae
Hopkins

Adult Douglas-fir beetles are light brown when young and become dark brown or black with reddish wing covers. They are somewhat hairy and range in size from 4.4 to 7 mm. The larvae are small, legless, the size of grains of rice, and white. Pupae are white to cream colored. Visible evidence of infestation includes patches of orange to reddish-brown boring dust in the bark or at the base of the tree. Resin streamers from attacks higher in the tree may also be present. Inside the bark, 6 to 30 inch egg galleries run parallel with the grain. Eggs are laid on either side of the gallery and when they hatch, the larvae mine perpendicular to the galleries.[1][2]

References
  1. Furniss, Malcolm; Kegley, Sandra. "Forest Insect & Disease Leaflet 5" (PDF). USDA Forest Service. USDA Forest Service, Pacific Northwest Region (R6), Portland, Oregon. Retrieved 23 July 2016.
  2. Dekker-Robertson, Donna; Griessmann, Peter; Baumgartner, Dave; Hanley, Don. Douglas-fir Beetle (Dendroctonus pseudotsugae). Washington State University and US Department of Agriculture. pp. 11–12.


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