The essentials in 30 seconds
The eastern carpenter bee (Xylocopa virginica) is about 3/4 to 1 inch long, with a fuzzy yellow thorax and a shiny, mostly hairless black abdomen; a bumble bee's abdomen is hairy and usually yellow-banded. Females drill a nearly perfect round hole about 1/2 inch across, usually on the underside of a board, go in about 1 inch, then turn 90 degrees and tunnel along the grain. Coarse sawdust and yellowish stains below the hole confirm an active nest. Damage is slow, but tunnels are reused and extended every year. The best protection is paint or varnish on all exposed wood; stain gives little protection. Treat active holes with an insecticide dust at night, wait a few days, then plug them in the fall with steel wool or copper mesh and wood filler or a glued dowel, and repaint.
- Males hover and dive at people but have no stinger; females sting only if handled.
- Woodpeckers dig into infested boards for the larvae, so fixing nests early saves your trim.
- Carpenter bees eat pollen and nectar, never wood, and they are important pollinators.
Carpenter bee vs bumble bee
The two look alike at a glance (bumble bees are "bumblebees" in British English), and both are large and noisy. Look at the abdomen first.
| Feature | Carpenter bee | Bumble bee |
|---|---|---|
| Abdomen | Top mostly bare, shiny black | Covered in hair, often with yellow bands |
| Head | Nearly as wide as the thorax | Clearly narrower than the thorax |
| Size | About 3/4 to 1 inch | About 1/2 to 1 inch |
| Nest | Tunnels drilled into wood | Colonies, usually in the ground |
| Social life | Each female nests on her own; a mother and daughters may share a nest | Social colonies with a queen and workers |
| Behavior near people | Males hover at eye level and chase other insects | Busy at flowers, usually ignore people |
Males and females
- Males have a yellowish-white patch on the face. They guard territories around nests in spring and fly at anything that moves, including your head. They are bluff: males have no stinger.
- Females have an all-black face and strong jaws for drilling. They have a stinger but are docile and sting only when handled or trapped against the skin.
When carpenter bees are active
Knowing the calendar tells you when treatment works and when it is wasted effort.
| Season | What the bees are doing | What you can do |
|---|---|---|
| April to early May | Adults that spent the winter in old tunnels come out and mate; males guard territories | Treat holes at night; set up painting jobs |
| Late spring to early summer | Females clean or extend old tunnels or drill new ones, about 1 inch every six days, and lay 6 to 10 eggs in a row of cells, each with a ball of pollen | Note every active hole; treating sealed cells now reaches little |
| Summer | Larvae develop; egg to adult takes about seven weeks | Watch for woodpeckers |
| Late August | New adults come out to feed on nectar | Treat open holes |
| Fall and winter | Adults return to the tunnels to spend the winter | Plug holes and paint, once activity stops |
There is one generation a year in the north and sometimes two in the south. Because the same tunnels are used year after year, an untreated board gathers more bees each spring.
Carpenter bee holes and damage
Signs of an active nest
- A round, clean-edged hole about 1/2 inch across, often on the underside of a fascia board, rail, deck joist, eave or windowsill.
- Coarse sawdust on the ground or surfaces below. Fresh sawdust means the nest is in use.
- Yellowish to brownish streaks of droppings and pollen below the hole.
- Males hovering near the same spot day after day.
- Bigger, ragged holes nearby: woodpeckers digging for larvae.
Which wood they choose
Eastern carpenter bees prefer bare, weathered softwood: cedar, redwood, cypress, pine and fir, especially straight-grained boards more than 2 inches thick. Typical targets are fascia boards, eaves, decks and deck rails, siding, unpainted doors and windowsills, shingles and wooden garden furniture. They largely avoid hardwoods, bark-covered wood and well-painted surfaces, and they leave aluminum and vinyl siding alone.
How serious is it
A single new gallery is a few inches long and does little harm. The trouble is reuse: galleries are extended each year and can reach about 10 feet in a heavily used timber. A University of Georgia study of a decade-old bench found a single 7-foot board with 15 entry holes and 28 feet of tunnels in total, yet even the worst board had lost only 18 % of its wood in ten years. Structural failure is rare, but repeated nesting weakens rails and trim and stains the surface.
Woodpeckers are often the bigger cosmetic problem. They tear open the face of the board to reach larvae and overwintering bees, and an infested board keeps attracting them. Plugging and painting stops both.
If you find damage that looks different, such as soft, crumbling wood, mud tubes or many tiny exit holes, read our guides to termites and woodworm.
How to stop carpenter bees nesting
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01
Paint or varnish all exposed wood
Use an oil-based paint or polyurethane on every surface, including undersides and board ends. Stain alone gives little protection. Penn State suggests painting in the fall, when bees are not drilling.
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02
Inspect the finish every year
Touch up chips and bare patches before spring.
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03
Fill cracks and depressions
Bees often start a hole where the surface is already uneven.
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04
Cover rough ends
Protect exposed timber ends with metal flashing or wire screening.
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05
Choose materials for repairs
Hardwoods, painted wood, or aluminum and vinyl trim are rarely attacked.
How to get rid of carpenter bees and plug the holes
Timing makes the difference. Once a female has sealed her eggs and pollen inside the cells, an insecticide in the entrance reaches little of the brood. Treat when adults are moving through the hole: early spring as they become active, or late summer and early fall when the new adults come and go before winter.
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01
Find active holes by day
Look for fresh sawdust and bees entering. Mark each hole with tape.
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02
Treat after dark
The bees are inside on cool evenings. Use a flashlight covered with red cellophane: bees see red light poorly.
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03
Puff dust into each hole
A bulb duster pushes an insecticide dust labeled for carpenter bees deep into the tunnel. Bees walking through spread it inside. Some products are for professionals only; read the label.
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04
Wait before plugging
Leave the holes open for a day to a few days so returning bees contact the dust.
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05
Plug the hole
Pack it with steel wool, stainless steel or copper mesh, which bees cannot chew, then finish with wood filler or putty (or a wooden dowel glued in place). Ohio State also suggests filling the gallery with sealant first if you can.
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06
Repaint
Seal the repair and the whole board so it is less attractive next spring.
If you plug an active hole without treatment, trapped bees can simply chew a new exit. That is why plugging is best done in the fall, after activity stops, or after a treatment.
Other options and their limits
- Surface sprays on bare wood give short protection at best, as residues break down within weeks or months. University of Georgia entomologists do not recommend them.
- Borate wood treatments work poorly because carpenter bees do not eat the wood they remove.
- Traps sold for carpenter bees have no peer-reviewed studies behind them, and an established nest produces only 1 to 20 bees a year, so catches rarely change much.
- Swatting females near the nest or probing tunnels with a stiff wire to kill larvae works for a few holes.
Why carpenter bees are worth keeping around
Carpenter bees feed only on nectar and pollen, and they are strong pollinators of garden and wild plants. In one University of Georgia study, bees from 23 nests made about 7,150 foraging trips between May and June and gathered an estimated 8.6 billion pollen grains. Old nests also shelter other beneficial insects, including mason bees and mason wasps.
A sensible goal is to protect the wood of your house rather than wipe out every bee in the neighborhood. Painted wood steers them elsewhere, and treatment can be kept to the few holes that matter: those in trim, rails and structural timber.
When to call a pest professional
- Holes are high on eaves, soffits or gables.
- Many holes in one board, or woodpecker damage spreading along the trim.
- A railing, deck joist or stair stringer feels soft or weakened: also ask a carpenter to assess it.
- Someone in the household is allergic to stings.
Ask what product they will use, how they will treat the tunnels rather than the surface, and whether plugging and repainting are included.
For wasp nests in eaves and shutter boxes, see our guide to Asian hornets and wasp nests.
Carpenter bees: frequently asked questions
Do carpenter bees sting?
Males have no stinger, even though they dive at people. Females can sting but rarely do unless handled.
How do I tell a carpenter bee from a bumble bee?
Look at the abdomen. A carpenter bee's is shiny and mostly bare; a bumble bee's is fuzzy and often banded yellow.
What do carpenter bee holes look like?
Neat, round holes about 1/2 inch across, often under a board, with coarse sawdust and yellowish stains below.
How do I get rid of carpenter bees?
Puff an insecticide dust into active holes at night, wait a few days, plug them with steel wool or metal mesh and filler, and paint the wood.
When should I plug carpenter bee holes?
In the fall, once the bees are inside for winter and after treatment, or any time after activity has stopped.
Do carpenter bees eat wood?
No. They chew tunnels to nest in and push the sawdust out. They feed on nectar and pollen.
Does painting wood stop carpenter bees?
Yes. Paint or varnish on every exposed surface is the best prevention. Stain alone gives little protection.
Why are woodpeckers pecking my siding or fascia?
They are often digging out carpenter bee larvae. Treating and plugging the nests removes the attraction.
Sources
University extension guidance, checked on 27 October 2026.
- Ohio State University Extension · Carpenter bees (HYG-2074) ↗Size, identification of males and females, life cycle and timing, gallery size, preferred woods, paint versus stain, plugging materials, dusts and borates.
- Penn State Extension · Carpenter bees ↗Bumble bee comparison, 1/2-inch entrance and right-angle turn, wood over 2 inches thick, fall painting, night treatment with red light, waiting before plugging.
- University of California IPM · Carpenter bees ↗Treatment timing in early spring or fall, why summer treatment misses sealed brood, hardwoods, flashing and screening, dust safety, pollinator value.
- University of Georgia · Eastern carpenter bee ↗Male face patch, sawdust, woodpeckers, the bench study, pollen collection, surface sprays, metal mesh plugs and the lack of evidence for traps.
Hearing buzzing at the eaves?
Mark each round hole with tape this week, then plan treatment, plugging and a coat of paint for the fall.