The Deathwatch Beetle

You are never too old to learn something new, and recently  I found out a new fact about something I have been working with for decades - the death-watch beetle.  I've never really wondered why it was called that - too busy pulling hair out over how damaging it is to medieval carpentry, particularly oak and elm. However, the name apparently comes from the pre-NHS era, a  time when most people died in their homes. Whilst the ill were lying in their bed, the family collected around them waiting for the final moments, it was obviously a quiet time. This quietness meant that people could hear the tap, tapping of the male adult beetle  searching for a mate, and thus it was a beetle associated with the 'death watch'.

These beetles burrow their way into and infest old oak and elm timbers. The usual areas we see that can see infestations are the end of roof joists, rafters, pews - any damp oak or elm in a church basically. This is why lead theft is a real issue and can have leave a lasting legacy of destruction as once the timbers get wet it becomes much easier for the beetles to make their way into the wood and begin to undermine the structural integrity of these timbers. This is why it is so important for us to keep moisture out of our churches and to keep these timbers dry.

Here you can see the carnage caused by Deathwatch beetles on the timbers at St Peter's Church, Offord D'Acy in Cambridgeshire.



Although the tapping sound is created by the adult male beetles, as with all wood-boring insects, the damage is actually caused by the beetle larvae. Adult beetles only live for a few weeks, however, the larvae live cycle can last anywhere from 7 - 13 years and it these larvae which are burrowing away and eating at the historic timbers.   

Treating infestations can be very difficult. Using sprays or applying insecticides to the infested timbers does not reach the larvae living it the center of the wood. Using such methods does kill of natural predators such as spiders. At the Churches Conservation Trust we believe that prevention is much better than a cure, so that is why we believe that the best way to protect churches is to make it as difficult as possible for the beetle infestations to occur in the first place. We do this through constantly monitoring our churches for moisture and leaks and act swiftly if we see any potential problems. Lead theft has caused some major problems which is why installing roof alarms is vital for us to deter and prevent moisture and water getting into the timbers and softening them.

If we discover a major infestation we call in a structural engineer for help us in making sure the structure is safe and to carry out repairs to damaged timbers through splicing, bracing and cutting out infested parts of a timber and replacing it.

So next time you hear that tapping, you may just be hearing a Deathwatch beetle, in which case let us know.

By Sarah Robinson,

Sarah is Director of Conservation for the Churches Conservation Trust.


© Gilles San Martin The culprit - The death watch beetle, Xestobium rufovillosum about 7mm in size. Photo by  Gilles San Martin