Is woodworm ever really dead?

[brianhabby]

Is woodworm ever really dead?

If it is, how can you tell?

We have been given some wood for the Men's Shed that shows signs of woodworm, i.e. it has a number of holes. The guy who gave us it insists it is dead, but some members are wary of using it or even keeping it.

What do the experts on this forum think?

regards

Brian

 

[Roughcut]

In my total amateurish opinion I believe there are several species of wood boring beetle(woodworm) in the UK.
Their life cycles depend on the particular species but I believe most are in the 3-5 year period.
Obviously it depends on the severity of the infestation and the amount of damage done to the wood in that time period whether it would render it unfit for purpose.
Also there is a risk of the woodworm spreading to other furniture or structural timber in the vicinity.
I have heard that one way of observing if the woodworm are still active is to take an area of timber and count the number of holes which have already been made and then periodically check to see if they have increased.

 

[AndyT]

Yes it can be killed off. Their salesmen might sometimes exaggerate but the fundamental claim of timber treatment companies is that it is possible to kill wood boring pests and there must be thousands of houses and old pieces of furniture which have been infected but not reinfected.

If the piece is small (about the size of an old plane, for example) I like to fill in the visible holes with coloured wax. If new holes appear I will know I have a problem. I haven't had a problem yet.

 

[Benchwayze]

According to the 'Under the Hammer' program, the acid-test is: If there is frass (excrement) falling out of the timber then the worms are still active. This of course presupposes that after the beetles emerge, and the larvae are no longer active, they clear up their old frass before departing. 8)

 

[Sgian Dubh]

Is woodworm ever really dead?

Well, all insects die eventually. But the key question is what you do with wood that has at some point hosted common furniture beetle larvae (Anobium punctatum), sometimes known as woodworm - the adult just lays the eggs, and doesn't burrow, as I suspect everyone knows: it's the burrowing larvae laid by the adult that do the wood munching. Incidentally, it's best to stick to the name common furniture beetle to avoid confusion with other wood boring insects.

Wood becomes infested or reinfested given certain conditions. The beetle does not attack live wood in trees or wet unseasoned wood stored outside — it likes cool, damp conditions where RH remains at about 55 per cent or above. It will breed in dry dead branches of trees, fence posts, air dried wood stored in sheds, et cetera but objects and structural wood in centrally-heated buildings are very unlikely to support an infestation. Just because warm and dry internal conditions deters the beetle this does not stop it attacking roof timbers and sheltered wood under eaves, soffits, porches and so on.

The beetle prefers some wood species over others, although it will attack any wood, hard or soft, preferably wood with high starch content. It will also attack plywood and other man-made board, is fond of animal glue, and even infests books. It is very partial to timbers like ash, beech and walnut, but it seems to be much less fond of mahogany and European oak. Dry wooden furniture, e.g., indoor residential furniture that never gets above about 12% or 13% moisture content, and frequently dryer at 6% or 8% MC is a particularly harsh environment for common furniture beetle to survive. Research and data suggest in fact 12% is the lowest wood moisture content at which newly hatched common furniture beetle grubs can exist.

My recommendations are to dose the material with readily available insecticide designed for the job, available at most home improvement outlets, and avoid conditions likely to cause reinfestation, i.e., those described above. Slainte.

 

[tomasg]

Thanks for more beetle tips I can't seem to get enough info on this...
12% moisture content or less for the grubs not to survive..
If youve got small pieces and a big freezer and a small appetite you can surely get rid of them that way..

What i'd like to know about is re-infestation and pheromones
Does these flight holes , frass or dead anobium punctatum bodies contain
these pheromones that attract them back again .

Does anyone have any good knowledge on the steeley blue beetle ? ..Said to be the anobium punctatum predator
From the little ive read you will only find them in big infestations .
Could pheromones from these beetles keep em away ?

Sorry if im a bit off topic......
Lets hopefully say it stays that way for you .
Thanks
Tom

 

[custard]

I have this problem all the time.

Just at the moment I'm getting out the wood for a job, client wants two occasional tables and a writing desk plus chair, using book-matched solid Walnut with a flash of "sapwood" as a feature (sapwood in the context of Walnut is a bit misleading, Walnut often has true sapwood, dark heartwood, and then a paler heartwood which isn't really sap and is found throughout the thickness of the tree, that's why it's often steamed). Anyhow, I worked through the cutting list and in the back of my mind was the concern that I hope I don't encounter a lot of worm, as I've enough wood for this job but not a huge amount spare. Everything was going well and I got out the last book matched top for the occasional tables, no problems on the face side,

But when I flipped the boards over there's the dreaded worm!

I'm 100% sure that it's dead and gone, and in a bone dry modern house it's never coming back, but once again I'll have to explain all this to the client and they never look totally convinced. Either that or I'll let in a little patch and keep my mouth shut!

By the way, taking about Walnut, I don't want to hi-jack the thread but take a look at this rippled Black Walnut.

It's solid ripple from top to bottom (the photo doesn't really capture it) on eight and nine foot long, waney edged consecutive boards, and I managed to get 12 cubic feet of it. Now can someone explain this. Top quality, but still unremarkable and widely available Walnut, costs £70-80 a cubic foot. Totally rubbish E-Bay grade Walnut is still £50-60 a cubic foot. But this, once in a life time, completely flawless, Black Walnut of your dreams, cost £120 a cubic foot. Doesn't that strike you as a weird market failure? It's like selling a brand new Aston Martin at just twice the price of a ten year old Ford Ka.

 

[MartinCox]

Now that custard has broken the thread.....

What a superb piece of timber. Ideas just flow about how to use it.

Custard - are you able to tell us where there is more of it? As you say, twice the price but 10-times the quality

 

[AndyT]

Custard, that's a good reminder that when we see a tree, we should not just think of it as a piece of timber, but as a whole ecosystem housing hundreds of species.

Having vaguely remembered being told that, a quick search led me to this paper http://www.jstor.org/stable/2109?seq=1#page_scan_tab_contents which provides a handy table of the number of insect species resident in various sorts of tree.

British oak tops the chart with 284 species; Willow supports 266 and Birch 229.

It's a good job they mostly live on the surface!

 

[Sgian Dubh]

If youve got small pieces and a big freezer and a small appetite you can surely get rid of them that way..

Freeze treatments to destroy insect pests, including eggs, grubs and larvae work best when the temperature drops rapidly. The target temperature should be reached within twenty four hours throughout the object to be most effective. Insects can adapt to slow changes in temperature much better than they can cope with relatively quick changes. The freezer must be capable of taking temperatures down to at least -18ºC (-0.4ºF) and it has to be maintained for at least two weeks. If the freezer can maintain temperatures as low as –30ºC (-22ºF) the treatment period can be as short as three days.
Maintaining the moisture content of the wood can be a challenge. Small objects must be wrapped and sealed in plastic bags to help maintain moisture content levels, and if air can be evacuated out of the bag prior to freezing this helps further. After treatment the wrapping needs to stay in place until the object properly reaches normal temperatures to prevent condensation onto it as this may cause damage to finishes and so on.

What i'd like to know about is re-infestation and pheromones
Does these flight holes , frass or dead anobium punctatum bodies contain
these pheromones that attract them back again.

I've read discussions about that, but I can't add anything useful.

Does anyone have any good knowledge on the steeley blue beetle ? ..Said to be the anobium punctatum predator
From the little ive read you will only find them in big infestations .
Could pheromones from these beetles keep em away ?

I only know pretty much what you know. They eat common furniture beetle larvae, and don't chew wood, but as to the pheromone part of your question, I've no idea. You could try contacting a pest control company to see if they know. Slainte.

 

[RobinBHM]

What about inert gas treatment using nitrogen, carbon dioxide or helium and a tent? I believe its a method used to treat antiques and takes about 3 weeks.

 

[rdesign]

http://www.topline.ie/home-decor/paint- ... ve-5-litre

this is what i use prom clear universal wood preservative.. wouldn't recommend for food sage surfaces like turned bowls or counter tops :/ but takes a finish well after it dries and is suppose to kill the larva before they burrow through the top surface if any infestation is active.

got a load of air dried elm it was crawling in woodwork :/ it was free but upset i brought it into my shop...

 

[MIGNAL]

All I know is that the common furniture beetle loves Maple. Years ago I agreed to store a lot of expensive Violin wood for a friend who was emigrating. In terms of cu. ft. there was very little of it. In terms of £££'ss - thousands.
The following spring I began to see little flying insects land on the white painted walls of the workshop. I was familiar with these insects. I'd seen them before, during my 'house bashing' days, in areas of houses that had been infested with them.
I immediately looked at my stock of wood. Nothing. The violin Maple however had lots of newly formed holes and the frass. I even watched one of the blighters emerge!
I did nothing. Absolutely nothing. No freezing, no spray, no chemicals. I left the wood where it was, right at the side of my stocks, which was expensive musical instrument grade too. That was over 15 years ago. My stock was fine, never showed any signs of infestation. My friends Maple didn't get any worse. I still have it. He did admit to storing it in fairly damp conditions for a period of about 1 year, between another house move. My workshop is in an attic space, dry. Dry is the key. Which brings me back to my 'house bashing' days. All the woodworm damage that I came across was in damp/wet areas. Under baths that had leaked, skirting boards on damp walls, damp cellars. Given that I was an electricians mate for some 5 years I saw a lot of old Victorian houses, probably 200 of the things. I saw a lot of loft spaces, cellars and floor voids. The pattern was always the same: damp areas frequently showed signs of woodworm. Dry areas: none.

 

[Sgian Dubh]

What about inert gas treatment using nitrogen, carbon dioxide or helium and a tent? I believe its a method used to treat antiques and takes about 3 weeks.

The two non-insecticide forms of control woodworkers are most likely to encounter are freezing and high heat treatment, although other methods include radiation and gas treatments such as nitrogen, oxygen scavenging and carbon dioxide treatments. These gas treatments rely on the insects need for oxygen to survive, and denying it to them by one method or another eventually kills them.

Heat of 50ºC (122ºF) and higher, maintained for extended periods, kills most insects at all stages of their life cycle. As with freezing, holding the moisture content of the treated object at an appropriate level is vital. In the early 1990s the German Thermo Lignum company was a pioneer in developing insect pest control using a purpose built chamber system with temperature and humidity controls to prevent damage to treated objects. This system controls atmospheric RH at a set point decided by the customer [usually 50%] and raises temperatures to 52ºC (126ºF) in the chamber and treatment cycles last, on average, twenty four hours. House longhorn beetle is more tolerant and needs a temperature of 55˚C. Treatment times are therefore quicker than freezing and large furniture items can be treated effectively without the need for bagging.

Mignal's experience of furniture beetle and its fondness for 'damp' conditions is well worth bearing in mind. Keeping stored wood dry, below about 15% MC is a good way of deterring reinfestation, even if the wood has been attacked in the past. Furniture in most habitable buildings is generally safe, because most habitable buildings are 'dry', although there are sure to be exceptions that prove the rule. At the same time, the relatively sheltered but exterior woodwork surrounding the living quarters may still be susceptible to infestation, e.g., under-eaves, leaky roof spaces, soffits, exterior lean-tos, etc. Slainte.

 

[Sheffield Tony]

For objects that will fit, woodworm does not enjoy being subjected to a quick zap in the microwave oven. I've used this on wooden planes (with the iron removed !) - microwaves heat the water in the wood a little so it gets warm, but anything alive will be much wetter and a lot hotter :twisted:

 

[brianhabby]

A lot of very useful information here, thank you to everyone who has contributed. I think the best solution is for us to treat the wood with a suitable woodworm treatment. It is intended as turning blanks as there are some good thicknesses involved (3-4") so we are thinking of cutting into appropriate sized blanks and then immersing those in the solution. Cutting the blanks will also reveal just how bad the wood is inside and help us decide which pieces if any need dumping.

Once again, thanks for all the help,

regards

Brian