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U.S. Forest Service
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United States Department of Agriculture

Native Forest Insects

Several species of insects, native to North American forests, occasionally cause significant tree mortality across the landscape. For many years these insects may be a low, or endemic levels, but when conditions favor them, their populations can build up to damaging levels. In the South, the southern pine beetle is the most destructive insect pest of pine forests. Historically, the southern pine beetle has affected forests from Maryland and Virginia south to Florida and Texas, but recently infestations have been found in New Jersey and Long Island, New York. In the West, several species of bark beetles have killed millions of acres of forests from the Pacific Northwest, through the Rockies and south to Arizona and New Mexico. Recent outbreaks of the mountain pine beetle, spruce beetle and Douglas-fir beetle have caused the loss of millions of acres of conifer forests in many western states. In the spruce-fir forests of the northeast and western US, species of spruce budworms cause defoliation and mortality of their host trees when outbreaks occur. In the western US, the western spruce budworm annually defoliates hundreds of thousands of acres in the spruce-fir type. The spruce budworm in the upper Mid-west has been a chronic defoliator for many years. In Maine and northern New England, the spruce budworm has been at endemic levels for the past 30 years, but populations are building in Eastern Canada, and this cyclic insect may soon be impacting the forests of northern New England.

Mountain pine beetle damage

Mountain pine beetle infestation. Photo by Whitney Cranshaw, Colorado State University, Bugwood.org

Spotlights


Southern pine beetle

Photo by Erich G. Vallery, USDA Forest Service, Bugwood.org

Southern pine beetle

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Mountain pine beetle

Photo by Whitney Cranshaw, Colorado State Univ., Bugwood.org

Mountain Pine Beetle

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Western Spruce budworm

Photo by William M. Ciesla, Bugwood.org

Western Spruce Budworm

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Spruce beetle

Photo by Erich G. Vallery, USDA Forest Service, Bugwood.org

Spruce Beetle

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Spruce budworm

Photo by USDA Forest Service - Ogden, Bugwood.org

Spruce Budworm

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