Old active woodworm

Is that woodworm active? The answers in Yorkshire

Picture of Bryan Hindle CSRT CSSW GradIOSH

Bryan Hindle CSRT CSSW GradIOSH

Bryan is Technical Director of Brick-Tie Limited

Is that woodworm active or not?

Mmmm, is that woodworm active? A tricky one; especially if your surveyor says it isn’t, the specialist says it is and you don’t know where to turn. I’m from Yorkshire and I’d like to answer that for you.

A dead adult common furniture beetle on a window sill in Selby North Yorkshire
This is a dead adult furniture beetle in close up. Taken on a site in Selby North Yorkshire, where a house was infested and the client noticed these in the window sills

This article is designed to give you sufficient information to make this decision for yourself. You can tell if that woodworm is active or not. Ideally, before we start we need to recap on what woodworm is, before we decide if that woodworm is active.

Woodworm is a generic term and can mean many different insect pests, ranging from the benign Bark Borer beetle Ernobius mollis, to the bogey man of churches across the country Death Watch Beetle Xestobium rufovillosum. There are many others too, which can be called woodworm of sorts; House longhorn beetle (just run away if you have this – if you’ve found it you live in Surrey and your roof is already toast), to the very common Common Furniture Beetle Anobium punctatum.

So, for now lets, stick to the ‘woodworm’ you are most likely to be concerned about – Common Furniture Beetle or, CFB as I’ll refer to it from now in this article.

CFB is a widespread pest of softwoods and European hardwoods. You won’t find it in Mahogany or any of those exotic Asian and African hardwoods like Iroko or Teak. You will find it the timbers we’ve used for hundreds of years in West Yorkshire and across England: Oak, Elm, and Spruces like European Whitewood and Pines, like European Redwood. You know, the stuff making up your floor and roof timbers; the stuff you buy from B&Q, Haworth Timber or Travis Perkins.

The chances are that if you live near me (Yorkshire), and are buying a house, where ‘woodworm’ has been mentioned in a report, it’s Common Furniture Beetle – I mean CFB. A quick recap on the reasons behind the methods used to tell if that woodworm is active:

All ‘woodworms’ start out as eggs on the surface of the wood, which you can’t see and end up as beetles emerging from holes at the surface, which you can see. That is you can see the holes and sometimes you may see the beetles. You rarely see the small maggot-like grubs which do the damage to the timber. These live in the wood for anything up to 5 years in the case of CFB, before emerging as adult beetles to mate and start the life-cycle again. The grubs never see the light of day; poor things. However it’s not all bad news for them as they are born in a world of food and die in it, to be re-born as a flying beetle on the hunt for love and parenthood.

So, to answer the question is that woodworm active, we need to see new holes or new beetles; that is all. Woodworm are like buses; you can wait for years and then many come along at once. What are the chances of you being there to see that? Luckily the emerging beetles leave signs, which you can often see, with a bit of care. They also emerge in a ‘flight season’, which in the case of CFB is May to September or thereabouts (our central heating has screwed with their body clocks a bit). The emergence holes are known as ‘flight holes’. Clearly this is because the beetles can fly and in making the holes that is the thing they will tend to do. However, some, like Death Watch Beetles are lazy and tend to hang around on the wood for ages ? months or years in fact. Anyway, back to CFB;

So, how can we tell if that woodworm is active? Here’s a short list and some images from Yorkshire’s houses to help you.

1 – The holes have fresh fine powder around the edges or small piles of powder over them on horizontal surfaces (not powder shaken out by tapping or using a screwdriver ? that doesn’t count)

active woodworm signs from a house in York
This floorboard has been under a carpet in York for years – where has the bore dust come from? It is active woodworm

2 – The holes are new and weren’t there last time you looked (if you have old holes and the time, just mark a few in a square and check again in a year or so, to see if new ones appear.

marking woodworm flight holes in Pontefract to count how severe the infestation is and check for emergence later.
The Building Research Establishment say you can describe an attack of woodworm as ‘severe’ if there are more than 20 holes per 100mm run of timber but…. how old are they? Let’s mark them and come back next summer.


active common furniture beetle infestation in a roof in Ripon
Lifted loft insulation reveals active woodworm in the ceiling joists, with new bore dust and dead adult common furniture beetles on the plasterboards below.

3 – There are beetles running around on the wood; on white shelving nearby or dead on the timber or, in the surface of loft insulation (Check for Stegobium panacium first though)

Many adult common furniture beetles on a window sill in Selby
If you have this many woodworm running about in your window sills (like our client in Selby), call us. Do ask the surveyor to rule out Biscuit Beetle Stegobium panecium first though… it’s woodworm’s distant and harmless cousin.

4 – Most of the holes have old paint or varnish in them but some haven’t (check when the paint was applied and if less than 5 years ago it is active).

5 – Are there cobwebs, dust or debris with freshly ejected dust in them?

active woodworm leaving signs in a cobweb below a kitchen floor in Leeds West Yorkshire
Active woodworm emergence from a Leeds floor leaves tell-tale bore dust in cobwebs below it

6 – Is the underside of the lino, underlay or lead, marked by their attempts to emerge through it?

7 – Do some holes look very  ‘fresh’ compared to others in the same place?

woodworm damage to the underside of linoleom in Yorkshire
Emerging Common Furniture Beetles don’t eat their way out, they chew their way out. Here they have bored into the underside of the linoleum floor coverings on their way out. A sure sign of recent activity.

Less lists and more common sense about woodworm in Yorkshire

Now then, I have heard it said that the only way to know if that woodworm is active, is to get live grubs from the timber. That is true in the same way, that it is only possible to know if you have coronary heart disease if you cut out your heart and check it for fatty deposits – the only people who would do this are pathologists. Some posh surveyors like to use words like pathology and forensics in their job titles and company names. Don’t let that put you off; it’s not complicated.

The above are the ways a specialist timber surveyor like me, decides if that woodworm is active. It’s not rocket science so do please have a go at it yourself.

If the woodworm is active then don’t panic.

CFB can cause very severe structural damage but also it can often lead to a few nuisance holes here and there at worst. A probe with a screwdriver and a good whack with a claw hammer can tell you a lot about how badly a piece of timber is infested.

common furniture beetle structural damage to a floor in Harrogate Yorkshire
This floor in Harrogate destroyed by woodworm (common furniture beetle)


A partially collapsed floor in sheffield caused by woodworm
Ooops… a foot through the floor caused by active woodworm in this Sheffield house (see below)


active woodworm infestation in Sheffield South Yorkshire seen by Brick-Tie Preservation
Seen from below the floor in the floor void, this Sheffield lounge floor is giving way due to active woodworm infestation.

If in doubt call in an experienced Chartered Surveyor, who has good knowledge of timber infestations or, a qualified timber infestation surveyor – either independent or a contractor, who is a member of the Property Care Association. The certifications to look for are CTIS (Certificated Timber Infestation Surveyor) and CSRT (Certificated Surveyor in Remedial Treatment). Either will do, but I tend to favour CSRT (though I do hold CTIS), as the CSRT qualification examination places more emphasis on health and safety knowledge than CTIS, so that any treatment recommended should be subject to the required Coshh assessment at the point of specification.

If that woodworm is active then in most cases it will need to be treated. A CSRT surveyor like us, should be able to specify a safe and effective treatment schedule. The treatment should be applied by qualified and experienced technicians. These days, that mean staff with either the Property Care Association qualified technician certification (PCAQT), or the City & Guilds NVQ level 2 in damp proofing and timber preservation. Ideally those using these products should have both of these.

Can I treat my own woodworm?

Can you do it yourself? Yes of course. As I said it isn’t rocket science. DIY treatment for topical areas such as say, an odd bit of infested wood can be economical and effective. Follow the instructions carefully, only use chemical with a HSE registration number on the label and take the safety and health advice very seriously.

Larger areas of timber or structural members are best treated by professional timber specialists – Not least because effective treatment means saturating all the surfaces of the wood with the chemical. With the best will in the world most DIY enthusiasts can’t do this safely or economically. Professionals have the equipment and all of the training and knowledge needed to do this effectively and above all safely.

My advice would be to use my company here in Yorkshire (cheeky – sorry about that), or at the least a contractor member of the Property Care Association. PCA members must have the training, qualifications and insurance in place before they gain membership. They are checked for minimum standards of quality, service and safety regularly and, using PCA members rules out all the cowboy firms in one easy decision. Are non-PCA members all cowboys? Far from it; I know one or two who are fine. The trouble is that lay people do not have the depth of knowledge or the time to go through all the things, which need to be checked before choosing a specialist to treat that active woodworm. Using a PCA member takes much of that work and risk away, at the click of a mouse. You may like to know that we are one of the few PCA members to win the coveted ‘Contractor of the year award’ so I like to think we are one of the very best of the PCA members out there.


Safeguard Soluguard
For most active woodworm treatments in Yorkshire I recommend Safeguard’s excellent Soluguard Woodworm. It is a permethrin based contact insecticide of the micro-emulsion class – HSE approved – full strength and safe when used properly

I hope this has helped you learn to see if that woodworm is active.

If you have any questions call me or my customer service team. Our office staff are also PCAQTs so they can answer your queries as well as I can (almost). call the above numbers for friendly accurate advice.

Bryan Hindle CSRT CSSW

Want to know more about the chemicals used for woodworm treatment? Need a really good book on recognition of timber decay and wood boring beetles? This is my bible and I never survey timber without it in my briefcase.

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