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The eastern larch beetle (Dendroctonus simplex LeConte) is the only tree-killing bark beetle that colonizes tamarack, or eastern larch, (Larix laricina (Du Roi) K. Koch) in the Great Lakes region. Historically, outbreaks have been intermittent and of short duration, frequently following predisposing factors such as drought or defoliation. However, over the past two decades, this insect has been in a perpetual state of outbreak in parts of the U.S. Great Lakes region, a deviation from historic norms. From 2001–2021, the insect impacted 300,000 ha, or 60% of the tamarack forests in Minnesota. This activity has prompted renewed interest in the beetle’s chemical ecology, including aspects of host semiochemistry. While foliar chemistry has been well documented in L. laricina, characterization of the monoterpene composition of the phloem has been lacking. We collected phloem samples from 56 tamarack trees across 14 locations in Wisconsin and Minnesota and assessed the relative abundances of the major monoterpenes present using gas chromatography-flame ionization detector (GC-FID). Individual terpenoid components identified included α-pinene (39.4%) and ∆-3-carene (30.0%) followed by several other components in small (

The Japanese beetle, Popillia japonica Newman, was accidentally introduced to the United States from Asia in the early 1900s. First detected in a New Jersey nursery, it is currently established in 28 states in the United States and has been detected in 13 additional states, 3 Canadian provinces, and at least 3 European nations. Adult beetles feed on over 300 host plant species, including many agricultural commodities such as fruits, field crops, and ornamentals, often causing severe economic damage. We discuss invasion history, ecology, biology, and management options for this invasive pest species in North America.

The range of eastern larch beetle, Dendroctonus simplex LeConte, extends across northern Canada and the United States sympatric, with its host, eastern larch or tamarack Larix laricina (Du Roi) K. Koch. Eastern larch beetle has long been viewed as a nonaggressive bark beetle whose populations flare for short durations after periods of tree stress. Recent decades, however, have noted extended tree-killing behavior along the southern margin of the host's range in the Great Lakes region of North America that deviate strongly from historic patterns. This chapter examines the biology and life cycle of the eastern larch beetle and its impacts on tamarack forests in light of a changing climate. Impacts of warming temperatures and extended growing seasons are discussed as well as key areas of future research. The impacts of the eastern larch beetle on tamarack forests are likely to be amplified as climate warming continues.