woodworm

How To Treat Woodworm (and prevent it coming back)

Last Updated on

You approach your roof timber, floor board or beautiful piece of solid wood furniture. You look closely, and there it is. Tiny little holes bored into the surface, the dreaded woodworm signs! You brace yourself, and turn to the internet and type: ‘How to treat woodworm’.

Thankfully then this guide pops up and you relax, because I’m here to tell you exactly what to do to get woodworm-free.

Cost

Time

Difficulty


What is Woodworm?

The term 'Woodworm' actually refers to the larvae of wood boring beetles.

In the UK, there are several different species of woodworm, but as the name suggests, the most common offender is the Common Furniture beetle. 

When it comes to the level of damage inflicted on your poor home, the Longhorn Beetle is the worst offender.


Identifying Woodworm

The larvae of wood boring beetles usually have a white creamy colour with curved bodies. It’s very unlikely you’ll ever see the larvae because they stay hidden within the timber, feeding on the wood until they're full-grown adults.

Adult beetles have various appearances, depending on their species. For example, the Common Furniture beetle is a brown winged beetle, normally about 3-4 mm in length. 


Woodworm's Life-Cycle

The four key stages of the woodworm life-cycle are listed below in chronological order. As you'll see, the life-cycle begins with an egg and ends with a fully grown adult beetle muching away at your timber! 

  • Egg
  • Larva
  • Pupa
  • Adult beetle

Female wood boring beetles typically lay their eggs on the surface of the timber, inside cracks, crevices and pores.  

Safely tucked inside the timber, larvae cause damage by feeding on the timber for several years before they pupate and hatch as adult beetles.

Once they're grown up, the latest generation of wood boring beetles leave the safety of their timber homes to breed. Females find a suitable surface on which to lay their eggs, and the life cycle/damage continues...


How serious is Woodworm Infestation?

The extent of woodworm damage depends on the size of the infestation, the species, and what parts of the home have been infested. 

Not all woodworm are harmful. However, if left untreated, woodworm can weaken timber, causing severe structural damage. 

The Longhorn Beetle is known as the most damaging species, but any major infestation should be checked by a qualified professional.


What Environment Attracts Woodworm?

This depends of the species, as different types of wood boring beetles are attracted to different types of timber. 

Some prefer hardwoods like mahogany, oak and ash, whereas others prefer softwoods like cedar, pine and spruce. Remember, they all love damp wood because it’s easier to digest. Therefore, damp proofing is a must, especially if you've suffered from damp in the past.

Common furniture beetles are happy in both hardwoods and softwoods. Allthough they can been found all over wooden objects, they typically prefer damp floorboards and worn furniture with no varnsh.

Female wood boring beetles like hardwoods with around 30% or more moisture content. This environment provides their larvae with the highest probability of pupating into fully grown adults.

Having said that, you can find wood boring beetles living in wood with around 10% moisture content. Remember, the dryer the timber, the harder it becomes for them to eat and grow.

It's worth noting that the larvae only eat the sapwood/outer section of a tree because it's toxin-free and has more nutrients, as opposed to the heartwood/inner section of timbers like oak and pine. 

Therefore, if you have furniture made of high-quality heartwood, there's a much lower risk of getting a nasty woodworm infestation. 

lightbulb-o

Pro Tip: Sapwood is typically lighter than heartwood. Knowing this helps you identify where the risky areas are


Tools & Materials

Tools

  • Bucket (if mixing insecticide powder with water)
  • Drill (if dealing with Deathwatch beetle)
  • Gloves
  • check-square-o
    Mask
  • check-square-o
    Goggles
  • check-square-o
    Sprayer (for liquid solution)

Or

  • Brush (for gel solution)

Or

  • Applicator gun (for paste solution)
  • check-square-o
    A second brush for paint or varnish

Materials

  • Insecticide; either boron (in powder, gel or paste form) or permethrin
  • check-square-o
    Paint
  • check-square-o
    Varnish

Instructions For Treating Woodworm

Follow steps 1 and 2, then move to Step 3 of the set of instructions for the type of woodworm you have.

Signs of woodworm

woodworm

First of all, woodworm isn’t a worm, it’s a beetle. Small exit holes in the wood and crumbly edges made by larvae actually mean that the woodworm beetles are advanced, as the larvae has already turned into emerging adult beetles.

The beetle flies out of the hole, but returns to lay more eggs, that turn into larvae. Keep watch for frass, which looks like sawdust, as this is evidence the larvae are active and are clear signs of woodworm beetles emerging.

lightbulb-o

Pro Tip: Peter Cox suggests hanging fly strips in roof rafters to catch adult beetles and kill them

Identify woodworm

Now you know you have woodworm, check which type it is, as the woodworm treatment methods are different.

The common furniture beetle is, unsurprisingly, the most common type, the death watch beetle sounds scary but is reasonably easy to treat, while the longhorn beetle requires a professional bug killer.

Exit holes about 1-2mm across, surrounded by fine sawdust (actually a waste product called ‘frass;) indicate the furniture beetle, while larger exit holes and large pellets mean you’ve got the deathwatch beetle (not as scary as it sounds). Tiny exit holes and sticky frass suggest the longhorn beetle.


for Common Furniture Beetle

Indicated by exit holes 1-2mm across. Frass will be very fine.

Choose your insecticide

furniture beetle

I recommend Boron instead of Permethrin, as the latter is a man-made chemical that is harmful to the environment and can kill animals as well as insects. Do not use Permethrin in a house with pets.

Protect yourself

Insecticides are dangerous, so put on a mask and goggles to prevent irritation.

Dilute powder

If using a boron based solution, dilute according to manufacturer’s instructions. This is likely to be 1 kg of boron powder to 25 litres of water. You can buy ready made solution.

Apply first coat

​Spray solution onto wood, giving a thorough coating. Pre-made solutions often come with a sprayer attachment. Leave to dry.

Apply second coat

Spray a second coating when first is dry, usually after a couple of hours, but check the manufacturer’s instructions to be sure.

Apply gel

For heavy patches of infestation, apply the boron solution in a pre-mixed gel. 1 litre of gel provides coverage for 4 square metres.


For Deathwatch Beetle

Indicated by exit holes 3mm across or larger and pellets of frass.

Locate the Woodworm infestation

Tap the infected wood to see which areas sound hollow, this is where the woodworm infestation is.

Drill test holes

drill test holes

Drill holes around the edge of the infested areas to accurately work out how big a patch you are dealing with.

Drill more holes

​Drill holes in a diagonal polka dot pattern across the area that are 10mm wide. Drill down until 15mm from the other side of wood.

Fill holes

Fill holes to the top with boron paste using an applicator gun. 

lightbulb-o

Pro Tip: The DIY Doctor recommends attaching a small length of plastic tubing over the nozzle of the paste container for greater accuracy.

Insert dowels

Push dowel inserts into filled holes to trap boron paste. Use a cloth to wipe away excess.

Apply gel

Coat the outside of the wood with boron gel, allow to dry and apply a second coat.


For Longhorn Beetle

Indicated by very small exit holes and frass that appears sticky (as though it has been mixed with wood sap).

Check hole size

Commonly found in roof timbers, longhorn beetle exit holes are larger than the 1-2mm made by the furniture beetle.

Do your research

Check the Building Research Establishment (BRE) to see if longhorn activity has been reported in your area.

Contact a professional

If you think you have longhorn infestation, then you need to contact a professional for removal. The chemicals involved are not safe for a DIY job and will result in a lot of dead beetles!


Preventing Woodworm

Having gotten rid of woodworm, you don’t want it coming back, so here’s a few tips to help you stay woodworm free:

  • Keep your house well-ventilated and invest in damp proofing to fight rising damp. Woodworm love the damp, so keep a close eye on any timber that is in a damp environment. For more info about damp proofing, rising damp and damp treatment in general, make sure you check out our 'How to Treat Damp' guide
  • Adding to the point above, basements are notorious damp hot spots, especially basements without cavity walls (a cavity wall is crucial is damp defense). Therefore, basement waterproofing and condensation control is a must. Remember, when fighting damp, along with dry rot and wet rot, property care is your most powerful weapon.
  • It is easier for beetles to bore into wood that doesn’t have paint or varnish on it, so maintain these items regularly and follow basic rot treatment guidelines.

Final Thoughts

Hopefully you are now on your way to being woodworm-free using the woodworm treatment methods laid out in this article. Woodworm isn’t difficult to tackle, and it doesn’t need to be the end of your home or furniture. 

Being infested once doesn’t mean you will have a second infestation, especially if you take the proper property care precautions like damp proofing your property.

Do you have any family or friends that have spotted the signs of woodworm? If so, please send them this woodworm treatment guide so they too can be free of woodworm infestation.

About the Author Vicky

Blogger who spent childhood suffering through many house renovations, but at least now is old enough to design rooms to her taste

Leave a Comment: