The Research Phase

After the disappointing conversation with the wood worm treatment company (basically saying come back in 5 years time if what we've done hasnt had any effect), I set off to find out more about my illegal occupants.

Death watch beetles live in hard woods such as oak. The wood needs to have suffered some disease and the wood needs moisure content for the beetles to survive. The lavae are laid on
the wood and they burrough into the wood where they happily munch the wood until they mature. This typically takes 7 years. If the wood is not very moist they grow slowly and might take 12 years to mature. When they mature, they metamorphose into adult beetles. Adult beetles emerge from the wood in order to mate and lay more lavae eggs. The adults cant feed but can chew - they can live several weeks giving them enough time to find a mate and lay some eggs.

There is remarkably little information on the Internet about deathwatch beetles. As fear started to take over and I was began to wonder whether my house would fall down in the 5+ years whilst I waited for the bugs to die, I read everything I could find about these pests. Did I have a really bad infestation or was my colony simply ticking away and would slowly die out anyway?

Most infestations of death watch beetle have been there since the house was built. It seems mine have probably been there for hundreds of years and the house is still standing.

The information available about eradication seemed to be very much about what I had already done which is chemical treatment. I found some anecodatal stories on the Internet from deathwatch beetle sufferers who seems very relaxed about them - accepting their existence as being almost part of the charm of living in an old house. Personally I want to kill them all off!

I looked at boron paste and pellets. Normal chemical treatment uses some pretty nasty chemicals whilst boron is harmless to humans but poisonous to beetles. So I bought some Boron has started drilling some holes into my heavy oak beams to insert the boron pellets. After drilling several holes with the drill straining to makes holes into the aged oak I came to the conclusion that maybe I was doing more damage in a few seconds than the beetle would do in 7 years. So I topped....The boron paste doesnt need holes drilled but it discolours the beams - dilemma do I ruin the natural charm of my oak beams or smother them with boron paste....

Other articles suggested that death watch beetles need around 17-20% moisure content for the beetles to survive. So time to invest in a moisture meter. Well it seems my beams are arund 20% moisure content. Those near radiators are very dry - 0%.

Another article suggested that there is always a cause of the death watch beetles - they need to get moisure from somewhere and that is usually a leaking roof, window frame or some other building defect. I accept the argument however my house suggests this clearly cannot always be the case. I have deathwatch beetle on internal beams that cannot possibly be getting water from external sources, I have to admit that the beetles are more active on external beams.

This leads me to another discovery. When I bought the house I had damp. The company I employed solved the problem by tanking the sole plate wall. With hindsight I've discovered this probably wasnt the best solution. By tanking the brick sole plate wall it does mean moisture is trapped in the brick work whereas previously it would evapourate into the house (causing damp). Now the moisure on the brickwork is higher, the sole plate beam is now exposed to higher moisture content increasing the survival prospects for my noisy insects.