The bees drilling into your wood are almost certainly eastern carpenter bees, large black-and-yellow insects about three-quarters to one inch long. Getting rid of them involves a combination of treating active nests, trapping foraging bees, and sealing or finishing exposed wood so they don’t come back. The good news: a single bee’s tunnel won’t threaten your structure, so you have time to address the problem methodically rather than in a panic.
Make Sure You’re Dealing With Carpenter Bees
Carpenter bees are frequently mistaken for bumblebees because they’re roughly the same size. The easiest way to tell them apart is the abdomen: a carpenter bee’s rear section is shiny, smooth, and jet black, while a bumblebee’s entire body is fuzzy with visible yellow patches of hair. Male carpenter bees also have distinctive yellow or white faces.
The damage signs are unmistakable. Look for perfectly circular holes about half an inch in diameter drilled into wood surfaces, especially on eaves, fascia boards, deck rails, and pergolas. You’ll often see piles of coarse, yellowish sawdust on the ground below each hole. Fan-shaped yellow or brownish stains on the wood near the holes are another telltale sign, caused by sticky waste the female bee pushes out of her tunnel. Over time, those stains turn black with mold.
Each hole extends one to two inches straight into the wood, then turns at a right angle and follows the grain for six to twelve inches. A single tunnel is cosmetic damage at most. But carpenter bees reuse and expand tunnels year after year, and when multiple bees nest in the same board over several seasons, the cumulative damage can genuinely weaken the wood.
Treat Active Nests First
If bees are currently flying in and out of holes, you need to deal with the active nests before you seal anything up. The most effective approach is applying an insecticidal dust directly into and around each hole using a bulb duster or bellows-style applicator. The dust coats the inside of the tunnel, so bees contact it every time they enter or exit. Apply in the evening when bees are less active and more likely to be inside the gallery.
If you prefer to avoid chemical pesticides, a low-tech alternative is soaking a cotton ball in rubbing alcohol and pushing it as far into the tunnel as you can. The fumes will kill bees and larvae inside the gallery. This method works best when you can confirm the bee is inside the nest, so again, evening is your window.
Whichever approach you use, leave the holes open for a few days after treatment. You want returning bees to pass through the treated tunnel rather than boring a fresh hole somewhere else.
Set Traps to Reduce the Population
Carpenter bee traps work by mimicking existing nest holes. The bees enter through a pre-drilled opening, fall into a collection chamber, and can’t fly back out. Traps baited with dried bee parts and pheromones tend to perform better than unbaited ones, since the scent draws bees from a wider area. Hang traps near known nesting sites, ideally on the sunny, south-facing side of the structure where carpenter bees are most active.
Traps won’t eliminate an infestation on their own, but they meaningfully reduce the number of bees drilling new holes, especially during the spring nesting season when adults are most active.
Seal the Holes at the Right Time
Timing matters here. The best window to plug carpenter bee holes is fall, after the nesting season ends. By that point, adult bees have laid eggs and moved on, but the new generation hasn’t emerged yet. Sealing in fall means you trap larvae inside before they can chew their way out in spring.
Plugging holes during the active season (spring and summer) before treating the nest is a mistake. Bees trapped inside will simply bore a new exit, and returning bees will drill fresh holes nearby. Always treat first, wait a few days, then seal.
For the seal itself, rubberized wooden corks designed for carpenter bee holes work well because bees can’t chew through the rubber layer. Push the rubberized end into the hole until it sits flush with the wood surface. Standard wood putty or steel wool stuffed into the opening and covered with wood filler also works, though it’s slightly easier for a determined bee to penetrate. Once holes are filled, sand the surface smooth and paint or stain over it to discourage future nesting in that spot.
Finish and Protect Your Wood
Prevention is really the long game with carpenter bees. They strongly prefer bare, untreated, weathered wood. Painting, staining, or sealing exposed wood is the single most effective deterrent, and it’s the one step that keeps working year after year without reapplication of sprays or traps.
Oil-based paints provide the best barrier because carpenter bees dislike both the taste and the harder surface. Multiple coats are better than one. If you don’t want to change the look of natural wood, polyurethane or a marine-grade exterior sealant will also deter nesting, though not quite as reliably as paint. Stain alone is less protective than paint, but a quality exterior stain still reduces damage significantly compared to bare wood. Some homeowners add a stain additive specifically designed to repel wood-boring insects.
For structures where finishing isn’t practical, covering exposed wood with aluminum flashing, vinyl trim wraps, or composite lumber eliminates the problem entirely. Carpenter bees can’t nest in non-wood materials.
Natural Repellents and Their Limits
Citrus-based essential oil sprays, particularly those containing lemongrass oil and citronella oil, can deter carpenter bees from treated surfaces. Carpenter bees dislike the smell of citrus, and spraying these oils around eaves, deck posts, and other vulnerable areas may redirect them elsewhere. The limitation is duration: essential oil sprays break down in sunlight and rain, so you’ll need to reapply every few days during peak season to maintain any effect.
One important safety note: citronella oil is toxic to dogs and other pets. Keep citrus-based repellent sprays away from grass, walkways, or any surfaces your pets might contact, lick, or sniff.
Almond oil, tea tree oil, and plain citrus peel extracts are sometimes recommended online, but the evidence for their effectiveness is mostly anecdotal. They’re unlikely to cause harm, but they shouldn’t be your primary strategy if you already have active tunnels.
When to Call a Professional
Professional carpenter bee removal typically costs between $75 and $500, depending on the extent of the infestation and how accessible the nesting sites are. For a handful of holes on a single board, DIY treatment is straightforward and cost-effective. But if you’re finding dozens of holes across multiple areas of your home, or if nests are located in hard-to-reach eaves or dormers, a pest control service can treat and seal everything in one visit and often includes a follow-up inspection.
Professional treatment is also worth considering if the same boards have been infested for multiple years. At that point, the internal galleries may be extensive enough that the wood itself needs to be assessed for structural integrity, not just treated for bees.
A Note on These Bees as Pollinators
Carpenter bees are native pollinators found throughout eastern North America, and they play a real role in the ecosystem. Roughly 15% of agricultural crops are pollinated by native bees like carpenter bees. The males, despite their aggressive-looking hovering and dive-bombing near your porch, physically cannot sting. Females can sting but almost never do unless you grab or press on them directly.
If the bees are nesting in a location where you can tolerate them, such as a dead tree at the back of your property, leaving them alone is a perfectly reasonable option. The control measures above are for situations where they’re damaging your home, deck, or other structures you need to protect.