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Brown spruce longhorned beetle (BSLB) back/dorsal. Photo by Steven Valley, Oregon Department of Agriculture, Bugwood.org. -
Adult Brown spruce longhorned beetle. Photo by Nathan Lord, Longicorn ID, USDA APHIS PPQ, Bugwood.org. -
Brown spruce longhorned beetle larva in wood. Photo by Stephanie Sopow, Natural Resources Canada, Bugwood.org. -
Resin on tree infected by brown spruce longhorned beetle. Photo by Jon Sweeney, Natural Resources Canada, Bugwood.org. -
Irregularly shaped larval tunnels made by brown spruce longhorned beetle. Photo by Georgette Smith, Canadian Forest Service, Bugwood.org.
Scientific name: Tetropium fuscum Fabricius
Native range: Europe and Asia
At Risk
The brown spruce longhorned beetle (BSLB) was first detected in Halifax, Nova Scotia, Canada with earliest records dating back to 1990. The pest likely spread through untreated wood and wood products.
BSLB primarily infests spruce (Picea spp.) but can also attack firs (Aibes spp.), pines (Pinus spp.), and larches (Larix spp.). In its native European and Asian range, it is considered a secondary pest, attacking only stressed trees. However, in North America, it is attacking apparently healthy trees.
Damage results from larval tunneling within the wood. In North America, BSLB has also been associated with a wood stain fungus, Ophiostoma tetropii.
This pest is not known to occur in Minnesota
Biology
Adults are 1 to 1.5 cm long with a somewhat flattened body. They have black heads and pronotum, with elytra that are tan, brown, or reddish. The reddish-brown antennae are about half the body length, and the legs are dark brown.
Larvae are yellowish-white, slightly flattened, and range from 14 to 28 mm long. They tunnel into wood, causing most of the damage.
In Canada, one generation occurs per year. Adults are active from June through August. Females lay eggs in bark crevices. After hatching, larvae tunnel beneath bark. As larvae mature, they tunnel inward toward the heartwood to pupate. Larvae overwinter inside the tree.
Symptoms of attack
- Resin oozing from the bark
- Oval or round adult exit holes (4 mm in diameter)
- Frass-filled galleries beneath the bark (up to 6 mm in diameter)
- L-shaped galleries that penetrate the xylem (seen in spring when pupation occurs)
Contact the MDA via Report a Pest if you suspect an infestation of brown spruce longhorned beetle in Minnesota.
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