Tetropium fuscum

Name and Family

Brown spruce longhorn beetle, Tetropium fuscum, is a member of the the longhorn beetle family, (Cerambycidae).


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:


  • 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


  • Oval.
  • 1mm long.
  • White with a greenish tinge.


  • Whitish.
  • Up to 28mm long.
  • Head reddish-brown, up to 3mm in diameter.
  • Segmented like an intestine.


  • Whitish.
  • 17mm long.
  • 4mm wide.
  • Segmented like an intestine, difficult to differentiate from larvae.


  • 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 present in NS, but has not been detected in PEI to date.

  • Infestations of BSLB negatively affect our native forests, a large component of which is spruce trees. 
  • BSLB can be devastating to spruce populations under stress, as it reproduces best on damaged and stressed hosts. 
  • BSLB can impact timber harvests both in terms of yield and salability. 



  • Prevention and early detection are key in the management of this species. 
  • Brown spruce longhorned beetles (BSLB) are not currently found on Prince Edward Island, so efforts must be made to keep our trees safe from this invasive pest. 
  • When traveling long distances, avoid bringing firewood along. The beetles have historically spread through the transport of contaminated wood products, so not transporting and inspecting any transported wood is crucial in the fight against BSLB. 
  • Regulatory control measures have been put in place to prohibit the movement of raw spruce products from infested areas. Be aware of the regulatory status of the area you are traveling in/to/from.
  • BSLB has a lower reproductive success rate when infested host trees are otherwise healthy, so maintaining a healthy Spruce population through proper silviculture is key to preventing establishment. 
  • As the beetle prefers to infest unhealthy or damaged trees, clearing windfall trees and removing unhealthy or damaged trees from the area can help prevent infestation.
  • BSLB is regulated by the CFIA.  Please contact your local CFIA office with any sightings or suspect insects.
  • The “Don’t Move Firewood” campaign has placed bins at the two main vehicular entry points to PEI.


  • Monitor spruce trees (felled or not) on your property for signs of BSLB activity. 
  • If you have seen BSLB on PEI, the PEIISC wants to know about it. 
  • Report any sightings to the PEIISC. 
  • If possible, collect a specimen in a jar.
    • Take photos of the specimen and any associated damage for identification purposes. 
  • Proper identification is your first step in the fight against BSLB.
    • Several native beetle species look like BSLB. 
    • Native lookalikes include the Northern pine sawyer and the spotted pine sawyer. 
  • If you have a pool, check your filter regularly to see if any invasive insects like BSLB have been collected there.


  • Picea spp., spruces. Only known hosts to date in Canada.
  • Scotch pine (in Europe)
  • European silver fir (in Europe)
  • Larch (n Europe)


  • The entire province of Nova Scotia is considered infested. 
  • Scattered populations have been found around Calhoun, New Brunswick.


  • BSLB infestation is difficult to manage.  
  • If a tree is found to be infested, it must be removed immediately. 
  • The tree will die from the infestation within five years, so preventing further infestation rather than saving the infested tree should be the top priority. 
  • The tree can be cut down and chipped to kill all life stages of the beetle. 
  • Grind the stump afterward. 
  • A quarantine area may need to be established around the outbreak site, so communication with regulatory bodies is key in the early stages of an outbreak.
    • All spruce trees in a local area should be monitored for signs of spread. 
    • Nova Scotia is deemed such a quarantine area, as per this ministerial order.
  • In designated infested areas, harvesting and treating suspected infested trees can be a method of control. 
  • Trees in these areas should be harvested in the wintertime to generate the lowest possible chance of spread. 
  • Harvested wood that is heat treated with a specific treatment protocol is considered clear for sale in outside markets, as heat treatment has been shown to kill all life stages of the beetle.


  • Unique biological and chemical treatments have been employed successfully in North America.
    • The use of native parasitic wasps is currently being studied for application in a management setting. 
    • A pathogenic fungus has been shown to reduce fitness when it infects BSLB adults.
      • Infected beetles showed reduced lifespan and egg-laying capacity. 
      • Spores of the fungus have been incorporated into pheromone traps. 
      • These use synthetic sex hormones to attract beetles, disrupting their mating rituals and infecting them. 
      • The use of BSLB sex pheromones in the trap also ensures that other insects aren’t attracted to the trap, reducing unintended damage to local insects. 
    • Pheromone pellets are also aerially dispersed over infested areas, disrupting mating where they fall. 
    • Studies are ongoing to determine the effects of TreeAzin on BSLB.
      • TreeAzin is a professionally applied, injected insecticide that prevents infestation of wood-boring insects. 
  • These applications require specialized knowledge and equipment to be effective.


Brown Spruce Longhorn Beetle – Profile | Invasive Species Centre

Brown spruce longhorn beetle – more information (

Brown spruce longhorn beetle (

Brown spruce longhorn beetle (

BSLB Risk Mitigation Program – Canadian Food Inspection Agency (