The Asian and citrus longhorn beetles are killers of broadleaf trees. They're not in the UK yet, but there’s a high risk of them being imported on wood packaging.
Common names: Asian longhorn beetle and citrus longhorn beetle
Scientific name: Anoplophora glabripennis and Anoplophora chinensis
What does it affect?: many broadleaf trees
Areas affected so far: not currently widespread in the UK, one outbreak in Kent in 2012
Origin: Southeast Asia
Asian and citrus longhorn beetles both harm the trees they infest at all stages of their lifecycle. The adult beetles look very similar; they are very large black and white beetles that grow up to 37mm in length. They can be seen feeding on leaves in tree canopies. Signs of damage include:
The Asian and citrus longhorn beetles are non-native beetles with boring larvae. Adult beetles lay eggs in notches under the bark. These eggs hatch and the larvae burrow into the tree. Due to the very large size of the larvae (between 30 and 60mm long by the time they reach maturity) they cause extensive damage inside the tree as they feed on the wood. This damage can cut off water and nutrient supplies to the leaves and therefore cause the death of the tree. The damage can also cause structural failure of the tree.
They target a range of broadleaf trees including:
Credit: Heiko Küverling / Alamy Stock Photo
These beetles aren't present in the UK at the moment. There was an outbreak of Asian longhorn beetles in the UK in 2012, but it was eradicated and there have been no cases of the citrus longhorn beetle reported.
Globally, both species have spread from Southeast Asia to Central Europe and North America.
While these pests aren’t currently in the UK, the highest risk of spread comes from wood packaging from China. Their larvae are moved around in wood packaging material, wooden products and within infected plants, especially bonsai trees. The adults emerge and lay eggs on native trees to establish a new population.
Both species have become more prevalent in their native range after policy change in China to mass-plant hybrid poplar trees in public areas. These hybrids are particularly susceptible to the beetles, causing their numbers to increase dramatically. This has only helped the spread across Europe and North America.
Credit: Purestock / Alamy Stock Photo
Trees infested by the beetles are killed slowly over a number of years as the population builds up. Management of the pests during an outbreak involves felling of thousands of trees to stop it spreading. Asian longhorn in particular is causing serious problems to trees in the United States since its introduction in 1996.
As the climate continues to warm, these species will be able to establish more easily and quickly in the UK because the climate will become more like the climate from which they originate, therefore the problem is likely to get worse. These beetles are often intercepted by port authorities around Europe so it is only a matter of time before they are introduced again.
To combat the introduction of pests and diseases like the Asian and citrus longhorn beetles we have:
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