This article explains how to identify the musk beetle (Aromia moschata), where it occurs in the UK, how to prevent it, and how to control it if necessary.
In the UK, this beetle is primarily known as the musk beetle, but it is also referred to as the willow longhorn beetle, musk longhorn, or scent beetle due to its distinctive odour and its strong association with willow trees.
What does the musk beetle look like?
Adult musk beetles are large, metallic green or bronze beetles with a vivid iridescent sheen. They typically measure between 20 and 35 mm in length, and males have very long antennae – often twice the length of their body.
One of their most recognisable features is the musky, perfume-like scent released by adults, particularly when disturbed. The odour is not harmful but is often noticed when beetles are handled or found indoors.
The larvae are creamy-white, soft-bodied grubs that develop inside wood, where they bore through tree trunks and branches, mainly targeting willows.
Where are musk beetles found in the UK?
In the UK, musk beetles are primarily found in southern and central regions, particularly in areas with abundant willows and wetland habitats. They are commonly associated with lowland riverbanks, lakes, parks, and gardens where willow trees are planted.
Typical habitats include:
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Gardens and public parks with weeping or white willows
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Wetlands, riverbanks, and other riparian zones
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Nature reserves and botanical gardens
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Timber piles, willow logs or stored cuttings
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Occasionally inside homes, especially if infested wood has been brought indoors
They are most active from late spring through summer and are often seen resting on willow trunks or foliage during warm, sunny weather.
How can you recognise a musk beetle infestation?
Musk beetle infestations can be difficult to detect early on, as larvae develop out of sight inside the wood. In many cases, infestations are only noticed when adults emerge or when tree health declines.
Signs of infestation include:
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Oval-shaped exit holes, 6–10 mm wide, on trunks or large branches
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Accumulations of wood dust (frass) at the base of affected trees
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Wilting or dieback in upper parts of willows
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Adult beetles crawling on tree bark or nearby vegetation
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A strong musky scent near logs or woodpiles
Infestations are often localised but may spread if cut or infested wood is moved to new areas.
Where do musk beetles live and breed?
Musk beetles breed in living or recently dead willow trees. The female lays eggs in small cracks or under loose bark. After hatching, larvae bore into the sapwood and continue to develop inside the tree for one to three years.
They prefer:
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Mature willow trees, especially in damp environments
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Stressed or damaged trunks and limbs
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Recently felled or pruned willow wood left on the ground
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Wood stored in gardens, sheds, or outdoor log piles
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Dead or decaying limbs with some residual moisture
Development is typically faster in warmer, sunnier conditions where trees are already weakened.
What is the musk beetle’s life cycle?
The musk beetle undergoes complete metamorphosis, with a long larval stage.
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Eggs – Laid in cracks of bark on willow trunks or branches
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Larvae – Bore into the wood and feed for 1 to 3 years
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Pupae – Form a chamber near the surface and pupate for several weeks
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Adults – Emerge in summer, live for a few weeks, feed on foliage or sap, and mate
Adults are most commonly seen between June and August, especially in southern England.
How can you prevent musk beetles?
Maintain tree health
Healthy willows are less likely to be infested. Regularly prune, water, and monitor for signs of stress.
Remove decaying wood
Do not leave willow cuttings, prunings or stumps exposed. Burn or chip them promptly after cutting.
Avoid storing untreated willow wood
Do not bring willow logs or timber indoors unless you’re certain they are pest-free.
Inspect trees regularly
Check for exit holes, frass or signs of wilting, particularly on mature willows in parks, gardens, or near waterways.
Protect trees from physical damage
Avoid bark wounds from strimmers or lawnmowers that could provide egg-laying sites.
How can you control musk beetles?
Chemical treatments are not generally used for musk beetles, as infestations are rarely severe and treatment inside the wood is difficult.
Prune and destroy infested limbs
Cut and burn affected branches before larvae can mature and emerge as adults.
Avoid spreading infested material
Don’t transport firewood or timber from infested areas to new locations.
Encourage natural predators
Birds and parasitic wasps may help reduce beetle populations in natural environments.
Monitor beetle activity
During summer, look out for adults on willow bark and foliage to assess presence and spread.
Seek professional advice
In cases where important or heritage trees are affected, consult an arborist or local authority tree specialist.
Are musk beetles dangerous to people or pets?
Musk beetles are harmless to humans and animals. They do not bite or sting, and the scent they emit, while strong, is not toxic. However, their larvae can weaken trees structurally over time.
In gardens, parks, or nature areas, this may increase the risk of falling limbs. Proper maintenance and pruning reduce the likelihood of such risks.
Where in the UK are musk beetles most common?
Musk beetles are most frequently recorded in:
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Southern England, particularly in river valleys and lowland areas
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Central England, in parks and gardens with ornamental willows
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Wetland reserves and riparian woodland habitats
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Urban green spaces where willows are planted near water features
While not yet widespread across all of the UK, musk beetles are expanding in range as climate conditions warm and ornamental willows become more common. Regular monitoring and prompt removal of decaying wood remain the most effective ways to manage their presence.