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(Tetropium fuscum)

Name and Family

Brown Spruce Longhorn Beetle (Tetropium fuscum)


The brown spruce longhorn beetle (BSLB) is an invasive forest insect. It is native to Europe. The first occurrence in Canada was in Halifax in 1999, but it has been established in Nova Scotia since 1990. The beetle likely arrived in wood packaging brought over in container ships. (Natural Resources Canada)

Identification Guide

Here are some key features that may help to positively identify the brown spruce longhorn beetle:Adult beetles:

  • 8-17 mm long
  • Flat body with dark brown-black head covered with light-coloured hairs
  • Wing covers vary in colour from tan to reddish brown
  • 2-3 longitudinal grooves
  • Antennae are red-brown and about half of the body length
  • Adults lay eggs under bark scales and in bark crevices, larvae hatch 10-14 days later

BSLB Symptoms:

  • Holes in the tree bark, oval to round, ~4 mm across
  • Sap weeping
  • Feeding galleries (networks of tunnels) underneath the tree bark, up to 6 mm across, filled with sawdust-like material
  • Coarse sawdust may be found in and around the tunnels or plugging the entrance/exit hole
  • Invasive Species Centre BSLB Fact Sheet

What it does in the ecosystem

BSLB infest spruce trees in North America. The larvae bore into the tree and feed on phloem, fluid that delivers nutrients to tree roots. Infestations occur in the same trees year after year until the tree dies – usually in 1-5 years. The BSLB usually target weak trees. It is still present in central NS, but has not been detected in PEI to date.


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