Red-necked longhorn beetle (Aromia bungii)

What does red-necked longhorn beetle damage look like?

As this beetle spends most of its life as larvae inside the trunk of the tree, there are often no symptoms until the infestation is severe.

Symptoms include:

• The leaves turn yellow or red; they wilt and fall off the tree early as the larvae feed inside the bark creating tunnels and galleries, affecting the tree’s ability to transport water and nutrients around the tree.
• As larvae tunnel and feed they produce frass (sawdust-like material) which collects at the base of the tree.
• Oval shaped holes (6-10mm wide and 10-16mm long) are left when the adults are fully developed and chew their way through the bark and exit the tree.

What is the red-necked longhorn beetle?

Adult beetles are black and shiny with a bright red pronotum/thorax (neck). Adults are 20–40 mm long with distinctively long antennae.

Its lifecycle lasts 2-4 years. The larvae are active, feeding in the trees, until late autumn. They overwinter inside the trunk or branches, protected from cold temperatures, and are well adapted to survive in extreme climates. They pupate inside the tree in the spring, and the newly developed adults emerge during summer. Following emergence, the adult beetles mate and feed on mature or rotten fruit and leaves. The lifespan of adults is 47–55 days. It is the larval stages which damage the tree.

Where has the red-necked longhorn beetle impacted?

This pest is not currently in the UK. It was first found in Europe in 2008 when three adults were intercepted among wooden pallets in a warehouse in the UK. The first report of this species in the wider landscape was in Germany in July 2011 and it is now also present in Italy.

How did the red-necked longhorn beetle get here and what impact will it have?

The red-necked longhorn beetle is not currently in the UK. It is native to eastern Asia, including China, Korea, Taiwan and Vietnam. It’s recently been introduced to Japan.

If it does arrive in the UK, the most likely entry is from the live plant trade and in wood packaging material.

Global trade is a risk in the spread of this pest, as it is moved around the world in packaging or on live plants. And as temperatures increase in the future, it may become established in new ranges.

What impact will the red-necked longhorn beetle have?

After a few years of successive infestation, the tree will become severely weakened, produce less fruit, and may die.

The only fully effective way of controlling the larvae is to destroy the plant. Insecticides have little effect on the larvae inside the bark.

What are we doing about it?

It is important we look out for the early symptoms because once the adults emerge, the infestation could be heavy.

As well as this work we have:

• Developed a UK and Ireland Sourced and Grown assurance scheme to make sure that all the trees we plant and sell are produced in the UK. 
• Lobbied the government to improve biosecurity at border points to stop new pests and diseases entering the UK.
• Partnered with Observatree, a tree health citizen science project which trains volunteers to spot pests and diseases, thereby helping tree health authorities identify and manage outbreaks early.

What to do if you spot it

If you think you've spotted the 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.