Death-watch beetles

by Richard Jones

I wasn't spooked by the nocturnal ticking, but it was a tad irritating trying to get to sleep the first couple of nights with this amorous percussion going on all around us...

Death-watch beetleLast week a cow wandered into the garden. And although it was pretty impressive, and the great tits, greenfinches and green woodpecker were also nice touches, the thing that most excited me was a woodworm. How sad is that?

First that cow. I wasn't there at the time. It wasn't in East Dulwich either. As has become our tradition, we went off to the Isle of Wight for a week during the Easter break and found ourselves in a wonderful converted barn at the foot of St Catherine's Down and overlooked by Hoy's Monument, a spectacular ball-topped pillar, one of the island's most prominent landmarks. Returning from various forays one day it was obvious that a cow from the neighbouring field had found its way through the ancient hawthorn hedge, and there were deep hoof-prints all over the small area of lawn, right down to the picnic tables outside the back door.

Gazing out through the windows, at any time of day, we were met with what I'd usually consider equally exotic garden guests: pheasants, green finches, green woodpeckers and a lone (lost?) duckling. These were all charming finishes to the wonderful views far over the rolling fields and woods to the sea, and the chalk cliffs of Tennyson Down and The Needles beyond.

But being an entomologist, it was the woodworm beetles indoors that fascinated me most. Technically they weren't in the garden, but they were so impressive that I can't resist going on about them. They were, after all, Britain's largest and most sinister woodworm — the death-watch.

Named for their eerie tapping, in the gloom, beginning just after sunset, they must have seemed an ominous portent of doom to the worried family gathered around the hushed bedside of a dangerously ill person nearing their end. Coming out of the very timbers of the building, a rapid series of hollow rattles, quickly answered by another tapping on the other side of the room as if in mocking echo, it's no wonder they became associated with the ticking away of life itself.

But there is nothing so dark in their night-time rappings, it's just Morse code for "I'm here, where are you?" Living inside the wooden timbers of an old building, often in voids chewed through countless generations, head-banging is a good means of communicating with each other. I wasn't spooked by the nocturnal ticking, but it was a tad irritating trying to get to sleep the first couple of nights with this amorous percussion going on all around us. A few times I got out of bed and banged on the wooden rafters with a shoe. It shut them up for a few minutes.

The death-watch beetle, Xestobium rufovillosum, is seldom seen these days, and for this we have to blame a change in building practice. Unlike the domestic woodworm, which can be introduced into a house with an infested piece of furniture, the death-watch are only brought in with the hardwood construction timbers (usually oak) when a building is first erected. Then they gnaw away, generation after generation, for centuries. With the larvae taking 3-12 years before arriving at adult beetlehood, I guess our 200-year-old barn had seen (or felt) 20-50 generations.

Of course, I found all this thrilling, but how do I reassure our host that her holiday let will not fall down? The answer is that if left unattended it will fall down, probably in another 200 years when the wooden beams are more hole and beetle droppings than supporting timber, and the sponge-like shell finally gives way. At 5-7mm long, death-watch dwarf other woodworms and make considerable galleries in the wood. But in the meantime examine the situation every 10-20 years, inject with pesticide where necessary and replace timber when appropriate. There should be a fair few centuries of life and deathwatch yet in the place.

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Gardeners' World Web User 17/04/2009 at 13:35

I used to hear death-watch beetles in my 1820s town terrace house. I'd only hear them in March and April and was told that the tapping was one seeking out a mate. I haven't heard them for the last couple of years - maybe they've moved further down the terrace, or maybe my hearing's deteriorated!

Gardeners' World Web User 17/04/2009 at 14:57

I too have some death watch beetles but how do you find them when they are in some inacessable spot that cant be reached without tearing parts of the house apart?Any handy hints?

Gardeners' World Web User 17/04/2009 at 15:27

Fasinating! I wondered what the noise was when I was in a similar situation in a holiday house! At least I don't have to worry about it falling around my head...

Gardeners' World Web User 17/04/2009 at 15:29

I put my hoover on 'max' and try and suck the adults out from between the cracks in the wood using the hose attachment.

Gardeners' World Web User 18/04/2009 at 10:47

We have recently converted a barn and have Death watch beetle in the old oak beams. The knocking was eerie at first back in March hearing the mating calls but then the beetles appeared and died on exit from the oak. I am told this is normal because our heating will dry out the oak and the beetles will not survive. I am also informed that because of this we will not need to use insecticide. Does anyone know if this is so?

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