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Guidance published for managing great spruce bark beetle

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Dendroctonus micans

Guidance for forest managers on detecting and managing the threat to spruce forests from the Great spruce bark beetle has been updated and published in a new Practice Note from the Forestry Commission.

The great spruce bark beetle (Dendroctonus micans) is found in forests throughout mainland Europe. It damages spruce trees by tunnelling into the bark of the living trees to lay its eggs under the bark, and the developing larvae feed on the inner woody layers. This weakens, and in some cases can kill, the tree.

The beetle was first discovered in Great Britain in 1982 after it was accidentally introduced, most likely via a consignment of imported timber. It has become an established pest in Wales and western England, and has more recently expanded its range to southern Scotland.

Statutory controls against the spread of D. micans were first put in place in Great Britain in 1982. Following the discovery of three new outbreaks outside the main infested area, the Forestry Commission reviewed the controls and consulted the forestry industry on two options: extension of the designation of the infested area and a continuing policy of movement restrictions into Scotland and the north-east of England, or revocation of our EU protected-zone status. The second of these options was agreed, and from 15 May 2005 the movement within Great Britain of conifer wood and conifer bark was no longer subject to any treatment requirements.

Instead, for management of the pest we rely on deployment of the specific predator Rhizophagus grandis, with the designation of part of the west of Scotland as a ‘pest-free area’ out of which wood and bark can be moved without treatment under the EU plant passport regime.

Entitled ‘Minimising the impact of the Great spruce bark beetle’, the Practice Note provides managers with a framework for assessing the risks to forests, and advice on what to look out for if trees are affected. Guidance is also given on the control techniques which have been developed to minimise the impact of the beetle, and action which should be taken if the beetle is found.

Dr John Morgan, Head of the Forestry Commission’s Plant Health Service, said,

“The Great spruce bark beetle is potentially a serious threat to our spruce-based forestry and timber industries. However, the good news is that biological control by release and maintenance of Rhizophagus grandis appears to be exerting significant, long-term regulation of beetle populations at levels acceptable to forest managers.

“This refreshed guidance on managing this threat is therefore a welcome contribution to ensuring the sustainability of our spruce forests and the significant investment, industry and employment which they support.”

The guide is available as a PDF for free download from the publications area of the Forestry Commission’s website at

Note to Editor:

  • The use of R. grandis to control D. micans populations was developed by scientists at the Forestry Commission's Forest Research agency.

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