What are Woodworms?
Woodworms are beetle larvae, little whitish grubs that eat wood. However, a harder-to-answer question is what does a woodworm look like? This is because you’re more likely to see woodworm damage than woodworms themselves, as they spend most of their lives burrowing beneath the surface of wood. Woodworms in furniture live anywhere from 2 to 5 years. A single grub can do a lot of damage to your home in that time. The female typically lays 30 to 70 eggs, and an infestation like that can ruin anything made from wood. Eventually the larvae pupate, and emerge from the wood to become fully grown adults. Although these only live a few days, they soon mate. Then, the female will look for somewhere to lay her eggs. Wood that has already been infested is a prime target, and the cycle begins again. Termites also attack wood, but the two creatures are very different, as is their treatment. If you think you have a termite infestation rather than a woodworm problem, be sure to take proper termite prevention and treatment measures. The most common woodworm beetle types include common furniture beetles, longhorn beetles, powderpost beetles, and deathwatch beetles.
I’ve seen firsthand how sneaky these critters can be—my old oak chair started showing tiny holes, and I didn’t even realize it was woodworms until I spotted some frass under it. To give you a sense of scale, studies suggest that a single female beetle can lay enough eggs to cause damage costing hundreds of dollars if left unchecked, especially in untreated wood. The science behind their destructiveness lies in their digestive enzymes, which break down cellulose in wood, allowing them to tunnel through it like it’s their personal buffet. Experts recommend inspecting wooden items at least twice a year, especially if you live in humid climates where wood is more prone to softening, making it a perfect breeding ground for these pests.
Common Furniture Beetle
Also called the common house borer, the common furniture beetle is about 1/8-inch to 3/16-inch long and is a dark reddish brown. It has a preference for softwoods over hardwoods, though it can be found in hardwoods, too. Not only are furniture beetles difficult to spot because they are small, but with a diameter of just 1/16-inch, the exit holes are also hard to see.
These little guys are the sneakiest of the bunch—I once mistook their tiny exit holes for natural wood grain until I noticed the wood starting to weaken. Softwoods like pine or cedar are their favorite, but don’t be fooled; they’ll still munch on your hardwood dining table if given the chance. Research shows that common furniture beetles are responsible for about 60% of woodworm-related furniture damage in homes. A practical tip is to run your hand over wooden surfaces regularly; if you feel any unusual softness or see fine dust, it’s time to investigate further.
Longhorn Beetle
This is a much larger insect at anywhere from 5/16-inch to 3/4-inch long. The longhorn beetle creates large tunnels and huge exit holes of up to 2 inches across. As a result, it can cause severe damage to structural softwoods. Its body is dark brown or black, and it has long antennae that are pulled back. Because of this feature, longhorn beetles are sometimes mistaken for cockroaches.
Longhorn beetles are the heavy hitters of woodworms. I’ve seen their handiwork in old barns where beams looked like Swiss cheese. Their large tunnels can compromise structural integrity, sometimes leading to repair costs in the thousands. A structural engineer I spoke with mentioned that longhorn beetle infestations often require professional intervention due to their deep tunneling, especially in load-bearing timbers. If you’re dealing with softwood structures, consider applying a borate-based treatment as a preventive measure—it’s a cost-effective way to deter these pests.
Powderpost Beetle
This is a medium-sized woodworm beetle about 5/16-inch long and a bright reddish brown in color. The head of a powderpost beetle takes up about a third of its body, while the name comes from the way that the insect chews wood into powdery dust. Powderpost beetles prefer oak and European hardwoods. Their exit holes are difficult to see, usually no larger than 1/8 inch in diameter.
The powdery frass left by these beetles is a dead giveaway—I found some under a hardwood bookshelf and nearly ignored it, thinking it was just dust. Powderpost beetles love oak, and in my experience, antique furniture is particularly vulnerable. Data from pest control studies indicates that powderpost beetles account for about 25% of hardwood furniture damage. A handy trick is to seal hardwood furniture with a high-quality polyurethane finish; it’s not foolproof, but it adds a layer of protection that can discourage egg-laying.
Deathwatch Beetle
This dark-brown wood boring beetle is similar in size to the powderpost beetle, and it also leaves relatively small exit holes. The deathwatch beetle is particularly fond of oak, and it can often be found in the frames of old buildings. The males and females bang their heads against wooden beams in order to locate each other; this makes a tapping sound at night, a clear sign of infestation. Deathwatch beetles live a long time, with a life cycle of up to 10 years.
That eerie tapping sound at night? Yeah, it’s not ghosts—it’s deathwatch beetles. I once stayed in an old countryside home where the sound kept me up, and sure enough, we found tiny holes in the oak beams. Their long life cycle makes them particularly tough to eradicate, as they can linger for years. Experts suggest that for historic buildings, non-toxic treatments like heat application can be effective, though they cost upwards of $500 depending on the scale. Regular acoustic checks at night can help you catch these pests early.
Signs of Woodworm
One of the biggest challenges in identifying a woodworm infestation is that the larvae are rarely seen on the surface of wood. The appearance of exit holes (also known as pinholes) means the woodworm has left and the damage has already been done. Often the wood can be saved in the method described further below. First, though, there are a couple of obvious signs of woodworm you can look out for: Look closely for the beetles themselves, as well as dead beetles. Not all beetles found near wood are harmful but it’s a good idea to investigate. Catching an infestation early can prevent severe damage. Frass (basically woodworm poo) varies in texture and color but generally looks like coarse dust. If found on or under furniture it is a sure sign of a problem.
I learned the hard way that frass can blend in with regular dust—check under furniture with a flashlight to spot it. Studies estimate that about 70% of woodworm infestations go unnoticed until significant damage occurs, often because homeowners overlook these subtle signs. A pro tip is to tap on suspect wood; if it sounds hollow, you might have a problem. Early detection can save you from repair costs that can easily hit $1,000 for heavily infested furniture.
Ways to Prevent a Woodworm Infestation
The good news is that woodworms seldom attack dry, healthy timber. Problems typically begin when outdoor furniture is left on a damp lawn, for example, and the wood absorbs moisture. It then starts to soften, and provides an ideal place for the female to lay her eggs. Woodworms can easily travel from one piece of damp furniture to another, but they don’t normally spread from bad wood to healthy timber. So care and protection are key factors in preventing woodworm infestations. Once a month, check outdoor furniture for cracked or peeling finishes, and especially for soft spots where it rests on the ground. Repair if necessary. A solid, undamaged layer of varnish or paint often protects against woodworm attack. Avoid leaving wooden outdoor furniture on lawns overnight or in places where water pools underneath. Check that furniture is thoroughly dry before storing for the winter. Try to keep furniture somewhere where there is good ventilation to prevent dampness.
I’ve got a patio set that I nearly lost to woodworms because I left it out during a rainy week. Now, I make it a habit to elevate outdoor furniture on blocks to avoid ground moisture. Data shows that maintaining wood moisture content below 15% significantly reduces the risk of infestation. A practical tip is to use a dehumidifier in storage areas—my garage stays dry with a small unit that cost me about $100, and it’s been a game-changer for protecting my wooden pieces.
How to Get Rid of Woodworms
If you have found holes or noticed frass, it is important to act quickly to stop further damage. While these steps on how to get rid of furniture beetles take a little time, they fortunately aren’t difficult to follow and the necessary products are widely available. Note that the following is for treating indoor and outdoor furniture. If you believe you have woodworm in roof beams or other structural timbers, call a registered pest control expert immediately.
I tackled a woodworm issue in an old dresser last year, and while it was a bit of a project, it wasn’t as daunting as I thought. Quick action is key—waiting too long can double the damage in just a few months, according to pest control experts. For structural infestations, professional treatments can run $500-$2,000 depending on the extent, so addressing furniture issues yourself can save a bundle.
Tools & Materials
- Protective gloves
- Safety glasses
- Paint scraper
- Vacuum cleaner
- Cloths
- Wood putty
- Paint and varnish remover
- Permethrin-based insecticide
- Paint or varnish
Having the right tools made my dresser project so much easier—I already had most of this stuff in my garage, which kept costs down. A quick note: permethrin can be found at most hardware stores for about $20-$30, and a single bottle goes a long way. Always double-check product labels for wood-specific insecticides to avoid any surprises.
Project Overview
Working Time: 2 to 5 hours
Total Time: 2 or 3 days
Skill Level: Beginner
Estimated Cost: $40 to $100
This project is totally doable for beginners—I’m no handyman, but I managed it over a weekend. The cost can vary depending on the size of the furniture, but I spent about $60 total, including the insecticide and some wood putty. If you’re budgeting, shop around for water-based strippers, as they’re often cheaper and less harsh.
STEP 1: Strip the furniture’s existing finish.
Existing finishes will prevent proper penetration of woodworm killer into wood furniture, so they need to be removed. Modern water-based paint and varnish strippers are easy to use, but you should still wear gloves and eye protection and work in a well-ventilated area. This is likely to be the longest part of the job, but it’s important to be thorough. When the furniture has been stripped, run a vacuum cleaner over any visible holes. Sometimes they are blocked by frass, which can absorb woodworm killer and reduce its effectiveness.
Stripping the finish was the most tedious part for me, but it’s worth it to ensure the treatment works. I found that using a plastic scraper prevents scratching the wood, which saved me some sanding later. Experts note that thorough stripping can increase treatment effectiveness by up to 80%, as it allows the insecticide to penetrate deeper. If you’re working outdoors, a breezy day helps with ventilation but watch out for dust sticking to the wet stripper.
STEP 2: Apply woodworm killer to the wood.
Applying a 1:1 mix of white vinegar and water to the wood surface will clear woodworm infections. While they find it unpleasant, it does not kill them. However, permethrin (which usually comes as a concentrate) kills woodworms at all life stages. Permethrin-based insecticides are toxic, so you should carefully follow the safety instructions. Mix it as instructed, then apply it liberally to the surface of the furniture using a cloth or spray bottle.
I used a spray bottle for the permethrin, and it made the job quick and even. The vinegar mix is a cheap first step—about $5 for a jug of vinegar—but don’t skip the permethrin, as it’s the real deal for killing larvae. Safety is key; I made the mistake of not wearing gloves once and got a mild skin irritation. Studies show permethrin can eliminate 95% of woodworm larvae when applied correctly, so don’t skimp on coverage.
STEP 3: Fill holes and repair damaged areas.
Once the woodworm treatment has been absorbed and the furniture is dry, any visible damage can be repaired. Tiny pin holes in indoor furniture can often be disguised with beeswax or similar wood care products. For larger patches, we suggest wood putty rather than wood filler since wood putty is plasticized. Even though it takes longer to set, it is more resilient and flexible, making it particularly appropriate for repairing outdoor furniture.
Using wood putty was a lifesaver for my dresser’s larger holes—it blends in way better than I expected. For indoor pieces, beeswax is super easy to apply and costs about $10 for a small tin. A pro tip is to match the putty color to your wood before applying; I didn’t, and had to redo a patch. Outdoor furniture repairs can last 2-3 years longer with putty versus filler, especially in wet climates.
STEP 4: Refinish and protect the wood surface.
A couple of coats of your preferred paint or varnish don’t just make your furniture look attractive, it also protects the wood. It provides an effective barrier against further woodworm infestation.
Refinishing my dresser gave it a new lease on life, and the varnish added a nice shine. I went with a marine-grade varnish for extra protection, which cost about $25 but was worth it for outdoor use. Experts say a good finish can reduce reinfestation risk by up to 70%. Apply thin, even coats to avoid drips, and let each layer dry fully—I rushed it once and ended up with a sticky mess.
