The Eastern Larch Beetle, Another Threat to our Forests (Coleoptera: Scolytidae)

Abstract

Isolated infestations of the eastern larch beetle, Dendroctonus simplex LeConte, have been reported in North America for over 100 years. Historically, this species has been considered a secondary pest of tamarack, Larix laricina (Du Roi) K. Koch, infesting only weakened or recently felled host material. However, recent widespread outbreaks of this bark beetle in northeastern North America and Alaska suggest that the species can be a primary killer of trees. More than 1.4 million m3 of tamarack was killed in the Atlantic provinces of Canada from 1976 to 1986. No damage estimates are available for Quebec and the United States. Fire, flooding, drought and defoliation by insects are often important agents predisposing tamarack to beetle attack and fostering localized build-up of D. simplex populations which then spread to healthy stands resulting in a widespread outbreak. Key Words: Dendroctonus simplex, bark beetle, outbreaks, damage appraisal, predisposing agents, tamarack.