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Quick facts

Common name: eight-toothed spruce bark beetle

Scientific name: Ips typographus

What does it affect?: Scots pine, Douglas fir, Norway spruce, Sitka spruce

Areas affected so far: Kent, England

Origin: mainland Europe

What does eight-toothed spruce bark beetle damage look like?

The eight-toothed spruce bark beetle is most frequently found on fallen trees as it prefers stressed and dying trees. If the population increases, the insect will move to living trees.

Symptoms include:

  • Browning of the crown on live trees.
  • Needles becoming lighter in colour, forming mats and often falling to the ground.
  • 2-2.5mm entrance holes made by the beetles on the surface of the bark.
  • Frass (sawdust-like waste material) produced by feeding larvae can be found on the bark at the base of branches and trunks.
  • Woodpecker damage caused as the birds break off bark on attacked stems to feed on the larvae.

What is the eight-toothed spruce bark beetle?

The eight-toothed spruce bark beetle is a very small beetle, around 5mm long, which is cylindrical in shape, shiny and hairy, and dark brown when mature.

It is predominantly a pest of spruce, therefore plantations with only one species planted are particularly vulnerable to attack. Dramatic increases in beetle populations can then spread to neighbouring trees, including pine.

Boring holes of the spruce bark beetle on wood

Credit: Konrad Wothe / naturepl.com

What happens to the tree?

In late spring to early summer when temperatures reach 11-16˚C, the male beetles start to fly in search of new host trees. When the male finds a suitable tree, it will bore a nuptial chamber into the wood and emit a pheromone to attract up to four females. The first mated female will bore a gallery lengthways towards the top of the tree to lay her eggs in, and all subsequent females will bore galleries down the tree with niches for each egg. They can produce between 30 and 80 eggs.

The damage happens when the egg hatches; the larvae widen and lengthen the egg niche and bore a pupal chamber where they will pupate under the bark surface. This seriously harms the channels that transport water and nutrients in the tree, causing dieback of the upper branches and in severe cases, the whole tree.

The beetle can also carry a pathogenic fungus which can discolour the timber and impact its commercial value.

Where has the eight-toothed spruce bark beetle impacted?

The eight-toothed spruce bark beetle is found across mainland Europe and northern Asia.

It has been intercepted at UK ports in the past, but in 2018 it was found in a woodland in Kent. All host trees in the area were removed and incinerated to stop any spread. It is hoped that the quick action was effective and there will be no more outbreaks. That said, the risk of it being accidentally imported again is very high.

How did the eight-toothed spruce bark beetle get here?

We don't know how the beetle reached the site in Kent, but the main risk of introduction is on wooden materials and plants. The eight-toothed spruce bark beetle is able to fly over reasonably long distances and with additional wind and air movement; they have been recorded to travel up to 43 kilometres.

What impact will the eight-toothed spruce bark beetle have?

The initial outbreak seems to have been eradicated so on this occasion this pest won't spread. However, the beetle seems to have been at the site for at least five years before it was discovered, so it could be elsewhere but so far undetected. It could also be re-introduced to the UK.

Pine is one of the host trees of the eight-toothed spruce bark beetle so there is a concern for our native Scots pine forests.

What are we doing about it?

To combat pests and diseases like the eight-toothed spruce bark beetle we:

  • Only plant native tree species that have been UK sourced and grown. We do the same when working with partners and landowners to minimise the risk of introducing new pests like the eight toothed spruce bark beetle.
  • Lobby government to improve biosecurity at border points to stop new pests arriving in the UK.
  • We’re also a partner in Observatree, a project that trains volunteers to spot pests and diseases around the UK so they can alert us to any outbreaks.

What to do if you spot the eight-toothed spruce bark beetle

If you spot the signs and symptoms of this pest, report it to the plant health authorities via TreeAlert if you are in Britain or TreeCheck if you are in Northern Ireland.

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