The eastern larch beetle, Dendroctonus simplex, is reputedly a secondary pest but may attack and kill tamarack and ornamental larches throughout Canada, the northeastern United Stales, and Alaska. Isolated infestations of this pest have been reported for over 100 years. The first recorded widespread outbreaks of D. simplex started in eastern Canada and the northeastern United States as well as in Alaska in the mid-1970s. During the outbreak in the Atlantic provinces, in excess of 1.4 million m3 of tamarack was killed. No damage estimates are available for Quebec and the United States. Insect defoliators were the most common factors predisposing tamarack to beetle attack.
Langor, D. W. and Raske, A. G.
"A History of the Eastern Larch Beetle, Dendroctonus Simplex (Coleoptera: Scolytidae), in North America,"
The Great Lakes Entomologist: Vol. 22
, Article 6.
Available at: http://scholar.valpo.edu/tgle/vol22/iss3/6