Great spruce bark beetle regulations, information and advice for Scotland
The great spruce bark beetle (Dendroctonus micans) is a common pest of spruce and pine in mainland Europe but is not native to the UK. It tunnels into the bark of living trees to lay its eggs. The larvae then feed and develop, forming galleries that weaken, and in some cases kill, the host tree. The beetle was first detected in Wales in 1982 after it was accidentally introduced, most likely via a consignment of imported timber, a decade beforehand.
In the UK, Norway spruce and Sitka spruce are the primary hosts of this pest. Sitka spruce is Scotland’s most important commercial tree species and monitoring spruce health is a high priority for Scottish Forestry.
Maintaining the status of the conifer bark beetle Pest Free Area (PFA) of a large area of western Scotland, as free from D. micans (and a number of other bark beetles) enables the trade of conifer roundwood to the island of Ireland. More information on this PFA and the procedures that underpin it can be found here.
D micans is now an established pest in southern Scotland and is slowly extending its range northwards. The beetle is a capable flyer but long distance spread is also known to occur through the movement of infested roundwood. This map shows the Pest Free Area and the latest confirmed distribution of D. micans in Scotland.Scottish Forestry is working with the timber sector to promote the ‘Ditch the Debris’ message to reduce the risk of moving infested material into the Pest Free Area via timber haulage.
Once D. micans is detected, effective levels of control are achieved through the release of an extremely specific predatory beetle, Rhizophagus grandis, the supply of which is provided by a breeding facility run by Forest Research with licence approval granted from NatureScot. Although release of R. grandis currently offers a highly effective management solution it does not eradicate D. micans or prevent further spread, vigilance remains necessary to detect/treat new infestations and to track whether climate change alters the dynamics between R. grandis and D. micans.
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