These Collections Care documents have been produced using information from our Conservation Development Officer, Helena, to provide suggested information on Death-Watch Beetles including how to identify and treat them.

Death-Watch Beetle​

(Xestobium rufovillosum)

Size ​

Adult 4-6mm, larva 0.5-8mm​

Favourite Food​

Hardwoods, typically oak, especially if it is damp or water-damaged​

What to look for​

Larva – Cream coloured, curved grub with dark brown head and short legs at front (seldom seen)​

Adult – Long body, dusty dark brown with some yellow scales. Head almost hidden by helmet-like thorax

When the days are getting shorter and it is late afternoon and quiet in the museum, you hear a faint tapping sound. Could it be the Death-Watch Beetle? 

Tell-tale signs: ​​

  • Exit-holes left by emerging adult beetles in wooden objects, floorboards or beams, about 3-4mm in diameter (much larger than furniture beetle holes). ​
  • Small piles of droppings (frass) under the holes. This a yellowish, gritty dust with round pellets the size of a small pinhead.  

Larva ​

For up to 12 years the young death-watch beetle grub, like a chubby, cream-coloured caterpillar, curled into a half-moon shape, is munching its way through the wood of some prized museum object or even the timbers of the building itself, but from late spring onwards the adults emerge and look for mates. ​

Adult Beetles​

You may find the adult beetles lying on the floor or windowsills.  They are larger than woodworm beetles and look more dusty as they have scattered yellowish scales on their brown backs. The head is almost hidden under the triangular thorax. ​

They will probably have already mated and laid eggs in cracks and holes, so action is necessary to prevent further damage to the collection and any timbers in the building. Water damage to wood, especially with fungal attack, makes the wood more attractive to death-watch beetle, so be vigilant if you have had leaks or damp in the building.

What do you need to do? ​

If you find death-watch beetles, piles of frass or holes in the beams, floorboards or timbers of your museum, don’t wait – get professional help from a reputable woodworm specialist.    ​

If you find larger holes in wooden or wickerwork objects don’t panic, but do investigate further:​

  • Are the holes fresh and bright looking inside or dull and dark? New exit holes will be clean and bright and need action. Death-watch beetle holes are about twice the diameter of ordinary woodworm holes. Older holes will look dark and may have worn edges. ​
  • Is there grainy wood dust falling out of the holes or in little piles beneath the object? The dust or frass can fall out of old holes when the object is moved. If the holes and dust look bright or there are little piles under undisturbed objects, then the infestation is recent and needs action.​
  • Are there large dark brown beetles in the area (dead or alive)? Then you need to take action. Isolate the objects, then freeze them out! ​
  • Then follow our step by step resource for treating woodworm. Death-watch beetles can eat through a thin sheet of polythene, so wrap your objects in acid-free tissue, then in bubblewrap, with the bubble side inwards. This seems to confuse them.  ​

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Download the below the information sheet on how to identify and treat Death-Watch Beetles.