Adult pine shoot beetle
Steve Passoa, USDA APHIS PPQ, Bugwood.org
Pine Shoot Beetle
The common (or larger) pine shoot beetle (PSB) is native to Europe and Asia. It was first discovered in the U.S. near Cleveland, Ohio, in 1992.
Keywords: beetle, Coleoptera, PSB, pine, spruce, fir, larch, galleries, exit holes, lateral shoots, tunneling, boring, reduced tree height and diameter growth
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Overwintering PSB adults initiate flight on the first warm days of spring in search of host material, primarily pine. Adults quickly colonize recently cut stumps, logs, or, at times, infest the trunks of severely weakened trees. When populations are high, PSB may breed in spruce, fir, and larch logs in stands mixed with pine. Females initiate gallery systems and after mating, construct individual vertical egg galleries within the inner bark and outer sapwood. After hatching, larvae construct horizontal feeding galleries. Most complete development, pupate, and transform to adults in May and June. Newly formed adults tunnel through the outer bark, creating circular exit holes, and then fly to the crowns of living, healthy pines of all ages. Adults feed primarily inside lateral shoots, mostly in the upper half of the crown, from May through October. They tunnel into the center and bore outwards, hollowing out 1 to 4 inches of the shoot. After several weeks, adults often emerge and enter other shoots. Infested shoots generally bend near the beetles’ entry points, turn yellow to red, and eventually break off. When shoot feeding is severe, tree height and diameter growth are reduced.