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Invasive bark beetles

Bark beetles are insects which bore into tree bark to lay their eggs. The larvae then feed on the inner bark of the tree.

Published: 02 Oct 2026

Topic: Manage forests

Contents

In a healthy forest bark beetles are an important part of the ecosystem helping to decompose trees and providing food for other wildlife.

The two invasive conifer bark beetles we’re worried about

But there are two invasive conifer bark beetles we’re particularly worried about: 

  • Ips typographus (Eight-toothed spruce bark beetle)
  • Dendroctonus micans (Great spruce bark beetle)

Ips cembrae (Large larch bark beetle) and Ips sexdentatus (Six-toothed pine bark beetle) are not currently causing serious problems, but we are watching them carefully. 

None of these species are native to Scotland, but they can survive and breed here so could cause widespread damage.

Severe outbreaks of Ips typographus in mainland Europe have led to widespread tree death and emergency felling which has overwhelmed forest operations and flooded the timber market.

Climate change is increasing the risk

Climate change, especially drought and storms, makes conditions even more favourable for the beetles.

Extreme weather weakens trees making it easier for the insects to colonise them.

And a warmer climate can increase beetle numbers by speeding up their development and facilitating flight, so they spread further and faster.

This report provides a good overview of the potential impact of invasive bark beetles. 

The threat to UK conifer forests posed by Ips bark beetles (Forest Research website)

Bark beetle species of concern

Scientific nameCommon namePrimary hostDistribution in the UK (2026)Management if found
Ips typographusEight-toothed spruce bark beetleSpruceRecent outbreaks in southeast England but not breeding
Not currently present in Scotland		Sanitation felling and good forest hygiene
Dendroctonus micansGreat spruce bark beetleSpruceEstablished in central and southern Scotland and spreading northBiocontrol and good forest hygiene
Ips cembraeLarge larch bark beetleLarchWidespread in Scotland but not currently causing major problemsGood forest hygiene
Ips sexdentatusSix-toothed pine bark beetlePineNot currently breeding in ScotlandGood forest hygiene

Forest Research and EPPO have more detailed information on each species including photos of the beetles, typical symptoms and management advice. 

1/
Dendroctonus micans - the great spruce bark beetle.
Dendroctonus micans - the great spruce bark beetle
Credit : Gilles San Martin
Ips typographus - the eight toothed spruce bark beetle.
Ips typographus - the eight toothed spruce bark beetle
Credit : Gilles San Martin
Ips cembrae - the large larch bark beetle.
Ips cembrae - the large larch bark beetle
Credit : Gilles San Martin.
Ips sexdentatus - the six toothed pine bark beetle.
Ips sexdentatus - the six toothed pine bark beetle
Credit : Gilles San Martin

Practical steps to reduce the risk of invasive bark beetles

1. Prevent

Reduce the risk by keeping your trees healthy

Prevention is better than cure. Use standard good forest management strategies to make your forest healthier, more resilient, and more profitable. Then if invasive bark beetles do arrive, they are less likely to become established. 

Helpful strategies to reduce the risk of invasive bark beetle attack include regular monitoring and good forest hygiene, e.g. removing recently dead, infested, stressed, or damaged host trees. 

Be particularly vigilant after storms or other extreme weather.

Bark beetles thrive in trees which are living, but stressed or damaged

Look out for damage caused by wind, snow, forest operations, animals, or recreation, as well as trees weakened by successive droughts, disease, or other environmental stressors. 

Freshly windblown trees are particularly vulnerable to infestation. Regularly identify these weakened trees, and, where possible, plan to remove them. 

These resources can help you to proactively manage your trees, to be healthier and more resilient to invasive bark beetles (and other stressors):

Important - deadwood

When selecting deadwood to retain, try to avoid creating habitats for invasive bark beetles.

Prioritise removing windblown, stressed and recently dead spruce trees.

Older rotting wood and other tree species can be left to decay naturally to support rare and beneficial organisms.

Find out how to encourage biodiversity in your woodland

2. Monitor

Be alert for signs of invasive bark beetles and report anything concerning to TreeAlert

Invasive bark beetle larvae feed on the phloem and weaken trees by restricting the flow of nutrients.

As a result, infested trees can look obviously stressed with bronzing foliage, needle loss, and dead tops. You may also notice increased woodpecker activity (as woodpeckers feed on the larvae).

If you investigate further, you might see beetles, larvae, or larval galleries under the bark. 

Resin tubes around entry holes on the bark are a characteristic symptom of Dendroctous micans.

The impact and spread of Dendroctonus micans can be reduced with biological control. Forest Research may contact you to arrange this following your TreeAlert report. 

Report any signs of invasive bark beetles to TreeAlert

To report suspected great spruce bark beetle, use TreeAlert.

This online platform allows you to submit symptom observations, including photos and location, helping quicker diagnosis and action.

Use TreeAlert

3. Adapt

It’s more important than ever to plant the right tree in the right place for the right purpose

If you are planning a new forest or restocking after felling, you can design a site that will be more resilient to invasive bark beetles (and other threats) now and in the future.

  • assess the site using tools like myForest (mapping, planning and sustainability), Ecological Site Classification (tree species choice) and ForestGALES (risk of wind damage) - sites at higher risk of drought or storm damage are more vulnerable
  • choose trees which suit the site and are more ‘futureproof’. Scottish Forestry commissioned a shortlist of 28 productive species, including 14 conifers, well suited to Scotland's current and likely future climate
  • diversify planting as much as feasible with no more than 65% of a single species. We don’t know what the future will hold so planting a mix of trees, including both conifers and broadleaf species, helps spread the risk.
  • to minimise the risk of bark beetle attack consider your management approach. Would a Low Impact Silvicultural System (LISS) such as continuous cover forestry be appropriate?
  • develop contingency plans for pest outbreaks

There are various tools and resources to help you with creating a forest that is fit for the future and stays healthy and productive for many years to come. 

Download our bark beetles leaflet and poster

You can download this information as a leaflet and poster.

Let’s work together to stop invasive bark beetles becoming a serious problem in Scotland.

Download our invasive bark beetles leaflet Download our invasive bark beetles poster

Published: 02 Oct 2026

Last updated: 02 Oct 2026

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