Woodworm treatment update

[stevekendal]

Back to restoring with a Dansette looking like a tea strainer and me run out of the nasty stuff. Got bit of surprise that its now not easily obtainable, with my local DIYs no longer stocking small sizes and the injector cans that were particulaly effective. Plenty of Ronseal with Permethrin on the net but is it any good? And to brush on/saturate, or inject? Opinions please, Steve.

[dseymo1]

I wonder if just leaving it outside in this weather for a few days would kill the worm?
Any entomologists around?

[brenellic2000]

Lindane was banned by the EU (because it worked!) and Permethrin is on it's way out too for the same reason. They won't kill you unless you take a hefty swig!

Deep freezing doesn't really work on eggs as they remain dormant! Larvae live off moist cellulose/starch/sugars so the answer is more to do with getting a really dry environment... but it all depends on what bugs you've got active!

If all you've got is holes with dust then its too late to treat, but if you've got fine pin holes, then they may be active or dormant and its worth a soak. Alas the only real answer is fire!, but that is far too drastic a solution!

Barry

[paulsherwin]

Very cold temps will kill any living worms but not the eggs. You need to freeze for a couple of days, warm up for a month so the eggs think it's spring and hatch out, then freeze again.

Freezing does help but you really need to treat the wood with killer.

[Lloyd 1985]

Possibly a very silly idea here, but would microwaving them kill them off?! If the item in question actually fits in a microwave

[paulsherwin]

Microwaving things just heats them up. This would certainly kill the woodworm, but it wouldn't do the wood much good, and there would be problems with metal fittings.

[stevekendal]

All very interesting advice and much appreciated, but I just want to know bout the efficacy of the available treatments.

[EF80TVVALVE]

I have some old cigarette cards that say that (i think) white spirit or turps can kill woodworm, whether it is true or not I don't know (never tried it) well worth a go if you have the time.
thanks

[brenellic2000]

Microwaves work on boiling way away water content. The average MC of interior timber is around 9% kilned or 12-15% air dried (30%+ 'green') so it won't destroy the timber instantly!

'Woodworm' is the furniture beetle larvae chomping away on the residual cellulose/starch/sugars even in 'dry' wood at 9% MC. They are voracious! They emerge in the spring working their way back up to the surface - that is when the first dusty/gritty plugs and dust appears and that is when the woodworm killer is its most effective if you catch them in time. So treat suspect timber from Feb/March onwards.

Permetherin is 100% fine. Pure turpentine is a natural spirit and has naturals 'cidal' benefits but Turps-substitute (aka White Spirit) is petroleum based and is not effective.

The EU banned creosote and lindane because they worked. Permethrin is on its way out too so Heavens alone knows what they'll ban next!

Barry

[Lloyd 1985]

I have some Rentokil woodworm killer, but it didn't seem to work on my TV22's side panels! I soaked them in it back in may, and a couple of months ago while doing some work on it I saw sme new piles of sawdust and holes, I know they were new, as I'd only filled all the others a few days earlier. their currently inside a sealed bag with half the can of worm killer. I'll have a look later to see what that stuff has in it..

[brenellic2000]

Don't forget the larvae can be chomping away for 2-3 years inside the wood - they are not like chicken eggs which hatch after 21 days.

The furniture beetle lays its eggs in open cracks from where the larvae start to chomp away so it is not always easy to see where the infestation has begun. If is old plywood with animal glues the larvae can survive for years and travel quite some distance.

Painting/injecting pin-holes (ie: < 1/64" dia) can be effective but anything over is usually a 'flight' hole from where the pupated beetle has flown.

Fumigation in a sealed container is an option - but that is specialist work. For 99% of the time permethrin and perseverance is the only sensible answer. I don't know how good the new iodo-propynl-butyl-carbamates (IPBC) stuff is, but from my experience of pressure impregnation of timber, "new" ain't any better!

Barry

[paulsherwin]

Originally Posted by Lloyd 1985

I have some Rentokil woodworm killer, but it didn't seem to work on my TV22's side panels!

You do sometimes need multiple applications. Woodworm killer works by poisoning the wood, so when the eggs hatch out and start chomping away they die. It's difficult to treat all the wood in one go.

A number of substances were used before modern insecticides, including turpentine and paraffin (kerosene). These treatments work but are very smelly and create a fire risk. Ordinary furniture wax provides some limited protection.

[brenellic2000]

I have to correct you on that!

Insecticides attack the insect! You can't 'poison the wood' unless the timber has been pre-treated before furthur conversion but this is not done commericially in the furniture trade - unless horiticultural - for very many reasons.

The cells are of cellulose and any penetration into the cellulose is osmotic provided the cells are wet; dry timber is not osmotic! Timber impregnation is by air pressure on evacuated cells and is rarely 100% - mostly only up the veins, not laterally through the cells unless on some hardwoods, such as oak, which have permeable meduallry rays in which 'food' is stored. 'Woodworm' and fungii thrive on the residual sugars from the sap. Pretreatment destroys the food value of the sugars and starches.

The time to kill woodworm is when they are pupating nearest to the surface where the broken cell structure is most likely to seep into open grain and attack the insect, around spring time. Pouring insectide into the pre-flight bore holes reaches the grub eventually by osmosis - if you are lucky! But it is very difficult to determine where the next flight hole will appear.

Thumping the wood with a mallet will dislodge compacted dust at the likely flight hole if you are lucky! All post-treatment is hit and miss and needs several applications until no further dust is found - but that won't stop another attack later!

Furniture wax (beeswax) is edible and no defence against insect attack!

Barry

[electrogram]

Cuprinol woodworm killer seems very effective and seems to prevent future infestation, provided a very thorough job of applying it is done, for a radio cabinet liberally apply to the (unfinished) inside , leave for about 15 minutes to soak in, then apply another lot, make sure you get all the corners and edges. then apply to the holes on the outside, the smell can take weeks or months to completely disappear

[dseymo1]

I've got some DDT here if you'd like it
Can't get rid of the stuff - I've tried the local council and a pharmacy, but neither has facilities for disposal.

(O.T. - I understand that had DDT not been banned, malaria might well have been eradicated by now).

[paulsherwin]

Originally Posted by brenellic2000

Furniture wax (beeswax) is edible and no defence against insect attack!

Yes, but if the joints and cracks are full of wax the beetles won't lay eggs there.

[Sean Williams]

I have a gallon of rentokil "commercial" killer here (the bottle is unmarked however - the operative I got it from didnt want traceable roots....)

If it is of any use to anyone PM me

[Kevin Hoyland]

Hello.

I have woodworm holes in one of my Bush VHF54 but have not seen dust in the last 2 years. But reading this thread on woodworm killer will it work or not makes me think is it better to scrap the radio to stop the woodworm going to my other radios. Or do i go to Screwfix and get 5lt of Cuprinol 5 star complete wood treatment for £29.99. IF it will work and stop re-infestation.
It contains Propicnzole and Flurenoxuron .



Regards Kev.

[brenellic2000]

'Woodworm killers' on the general market are remedial - ie: post attack. They are nearly all nerve agents - usual ingested (eaten) but sometimes by contact (absorption).

They initially work by lining cell walls (they can't penetrate the celluloss except by osmosis) or by being absorbed in the soft chewed dust and making contact, eventually, with the larva and thereby killing it - hence the need for regular application. The insecticide remains active for a little while but only in areas properly treated - ie. via holes or via the end grain - painting it on to planed wood surfaces cannot penetrate into the wood!

Those chemicals available to domestic users are very weak for safety reasons - don't use 'professional use' only unless you do know what you are doing! 'Trade use' is a marketing term for DIY-cowboys and is not necessarily any stronger than domestic stuff!

As a sawmiller (we used to professionally impregnate timber - Bethell full-cell) I can recommend 'Cuprinol' products - (5-Star is an overkill!) - but formulations are always being changed for less toxic and unproven chemicals.

Paul, your point about beeswax is correct only in that it prevents the eggs from laying in exposed cracks, but the female's ovipositor can penetrate minute cracks and the wood cells if damp - ie: weakened cellulose cells - which bring me to the point about paraffin! These and fuel oils are not effecitive insecticides other than that the make the sugars inedible but they can and do weaken the cells structure so can never be recommended.

'White spriits' (organic solvents) are only used a carrier to take the insecticide into the cell stucture, the OS then rapidly evaporates giving the impression 'the wood has asborbed it'. OSs are being banned by the EU for obvious domestic reasons.

Most vintage radios etc use animal based plywoods often birch (a very sugary wood) (or if you are lucky, blockboard) so be vigilent for any infestation. Remedial woodworm killer is your only option other than professional fumigation or making a new cabinet as most plywood is now of resinous cores and phenolic resin glues... yet the finest plywood is still multi-ply aircraft and furniture grade.... Birch! And don't forget the industry standard veneer is less than 0.5mm thick so offers no resistance to insect attack!

Barry
Barry

[richrussell]

The Cuprinol 5-star stuff has worked well for me on a cabinet that had an active infestation when I got it, and it stops fungus attack nicely too (I bought a large amount for sorting out floorboards and joists, but had some left over in my garage so I used that on the cabinet). I painted it on the unvarnished inside and let it soak in. Then repeated a couple of times as instructed on the can.

However - it does tend to darken the wood quite a bit, so you might want to be careful if anything has a delicate pattern.

Previously I've had good results from the Cuprinol woodworm killer aerosol - it's amazing just how far away from the hole you inject it into it spreads along the tunnels and between the plies of the plywood.