Quick answer
A carpenter bee is a large, solitary bee, in the U.S. East mostly Xylocopa virginica, that chews a round half-inch hole into bare wood and tunnels along the grain to raise its young, without eating the wood.
It looks like a bumble bee but has a shiny, mostly hairless black abdomen. One bee does little harm, but tunnels reused year after year can weaken decks, eaves and trim.
Quick facts
The key facts about Carpenter Bee, with sources:
- Generations
- One a year in the North, sometimes two in the South 3
Key takeaways
- Carpenter bees drill round half-inch holes in bare, weathered wood and nest inside.
- They do not eat wood; they dig tunnels and pack them with pollen for their young.
- Males hover and dive at people but cannot sting; females rarely sting.
- Paint or polyurethane on exposed wood is the best way to keep them off.
- They are native pollinators, so prevention and plugging holes come before pesticides.
What a carpenter bee is and how it nests
A large black bee hovering under your deck or eaves in spring, next to a neat round hole in the wood, is almost certainly a carpenter bee. Large carpenter bees are 20 mm or more long, UF notes, against under 8 mm for the small carpenter bees that nest in plant stems 4.
Carpenter bees are solitary, and each female digs her own nest. She bores a hole about her own body width, slightly under half an inch, turns about 90 degrees and tunnels along the grain 3.
She then builds a row of cells, each stocked with pollen and nectar and sealed after one egg is laid 1.
Carpenter bees do not eat wood. The University of Nebraska notes they excavate nests but do not feed on wood 5. The shavings fall out as coarse sawdust below the hole 2.
Carpenter bees are also important pollinators 35, so the aim is to keep them off your wood rather than wipe them out.
How a carpenter bee builds a nest
- Emerge in spring: Adults that wintered in old tunnels come out in April and May 23.
- Mate and pick wood: Females favor bare, weathered wood more than 2 inches thick 1.
- Drill: The female bores an entrance about 1/2 inch wide, usually against the grain, then turns at a right angle after about an inch 1.
- Tunnel: She tunnels along the grain for 4 to 6 inches, at about 1 inch every six days 3.
- Build cells: She makes 6 to 10 brood cells, each with pollen, nectar and one egg 31.
- New adults: Egg to adult takes about seven weeks 3, and young adults emerge in late summer, feed and return to the tunnels to spend the winter 12.
- Entrance holeAbout 1/2 inch, round, drilled across the grain
- Right-angle turnAbout 1 inch in
- Main gallery4–6 inches along the grain in year one
- Brood cells6–10 cells, each with pollen and one egg
- Reused galleriesExtended by later generations, up to 10 feet
Measurements from Penn State, Clemson and Ohio State Extension. Source: [1] [2] [3]
Carpenter bee species in the eastern U.S.
| Species | Range | Look |
|---|---|---|
| Eastern carpenter bee (Xylocopa virginica) | Eastern U.S. south to Texas and northern Florida 4; the only large species in Pennsylvania 1 | Abdomen black with a slight purple tint; pale hair on the thorax 4 |
| Southern carpenter bee (Xylocopa micans) | Southeastern Virginia down the coast to Florida, west to Texas 4 | Metallic greenish-blue abdomen; body metallic purple 4 |
| Small carpenter bees (Ceratina) | Widespread; 21 species north of Mexico 4 | Under 8 mm; nest in pithy plant stems, not house wood 4 |
UF notes Xylocopa has seven species north of Mexico, and the two above are the only ones in the eastern U.S. 4. Males of many species have pale yellow or white faces, which you can see when they hover 52.
Example: how a few holes become a damaged fascia board
This example uses published gallery figures to show why small holes grow into bigger problems over years. It is an illustration, not a measurement of a real house.
| Year | Published figure | What happens to the board |
|---|---|---|
| Year 1 | One female digs 4–6 inches of gallery 32 | One clean hole; damage is slight 1 |
| Year 1, late summer | 6–10 young per gallery 3 | Several new adults winter in the tunnel 1 |
| Following years | Later broods enlarge and extend tunnels 1 | More holes in the same board |
| After many years | Galleries reach up to 10 feet 23 | Board can be weakened and stained |
One hole is a nuisance, but holes left open invite reuse. Plugging holes in fall and painting the wood breaks the cycle 1.
Where carpenter bees show up on your house and paperwork
On the house: unpainted doors, window sills, eaves, fascia, shingles, railings, decks, fences, sheds and wooden furniture 125. Stains just below the hole come from the bees’ droppings 1.
On a home inspection or wood-destroying organism inspection, an inspector may note carpenter bee holes or damage in exterior trim. Whether they count on a given state form varies, so ask.
On a pest quote, look for which areas will be treated, whether holes will be plugged and sealed, and whether a follow-up visit is included. Ask whether the company handles carpenter bees under its stinging insect service.
Signs of carpenter bees
- Perfectly round holes about 1/2 inch across in bare wood 52.
- Coarse sawdust or yellow frass on surfaces below the hole 25.
- Dark streaks on the wood below entrances, left by the bees’ droppings 1.
- Large black bees hovering near eaves or decks in spring 1.
- Most activity from May through July in Nebraska 5.
Do not handle the bees
Females can sting more than once if handled 3. Do not swat them, and avoid ladders near active nests if you are allergic. Severe sting reactions need 911. Never spray products near flowering plants or in ways the label does not allow. For pesticide exposure, call Poison Help at 1-800-222-1222.
Are carpenter bees helpful or harmful?
Benefits
Why carpenter bees keep coming back
Open tunnels are the main reason the bees return: young adults winter in old galleries, and later generations extend them 1, so a hole left open is likely to be used again.
Sprays also wear off fast. Ohio State says surface insecticides usually break down within weeks or months, and Clemson notes pyrethroid sprays last less than thirty days outdoors 32.
Stain alone does not help much either. Penn State says stained wood is not usually protected, and Clemson and Ohio State agree stains give little protection 123.
What drives the cost of carpenter bee work
Cost depends on the job, and we do not list prices. The main drivers are the number of holes, how high they are (ladder or lift work costs more), whether holes must be plugged and sealed, and how much wood needs repair or repainting.
Over the long run, most of the money goes to carpentry and paint rather than pest control. Painting exposed wood with oil-based paint or polyurethane is the most effective deterrent 2. Replacing badly tunneled boards may cost more than any treatment. Our pest control cost guide explains how pest quotes are built.
How carpenter bee problems are usually handled
- Inspect: Map every hole, especially on eaves, decks and fascia.
- Treat active holes if needed: Extension guides describe placing a labeled insecticide dust into openings, ideally at night when bees are inside and less active 13. Follow the label exactly.
- Wait before plugging: Penn State says not to plug holes right away so bees contact the dust; Ohio State says to wait a few days 13.
- Plug: Fill holes with a dowel and wood glue, wood putty, or steel wool or copper gauze under putty 31.
- Paint: Paint or varnish the wood; Penn State says to plug and finish in fall 1.
- Check again in spring: Look for new holes when adults emerge in April and May 2.
A professional can reach high eaves safely, and a pest exclusion plan can cover the rest of the house.
Preventing carpenter bee damage
- Keep exposed wood painted with oil-based paint or polyurethane, and check the paint often 23.
- Do not rely on stain alone 23.
- Use pressure-treated wood where it fits; Clemson says it helps deter nesting 2.
- Plug old holes in fall so they cannot be reused 1.
- Look over decks, eaves and sheds each spring.
Paint beats spray
Clemson calls a painted surface the most effective deterrent. Ohio State and Clemson both say stains give little protection 23.
Sealing gaps with caulk keeps other pests out of the same trim.
When to call a professional
A pest professional makes sense when holes are high on eaves or fascia, when there are many of them, or when someone in the home has a bee sting allergy.
Soft, cracked or heavily tunneled boards need a carpenter, and load-bearing wood such as deck joists should be checked for strength.
Pesticide and licensing rules for carpenter bee treatment
Federal (EPA, FIFRA): Any insecticide must be EPA-registered and used only as its label allows, including site and pollinator precautions. See our pesticide safety guide.
State licensing: Companies that treat for pay are licensed by the state. See pest control licensing.
Protection status: Our sources describe carpenter bees as pollinators but do not name a federal or state protection for them. Check your state before any large-scale control.
Carpenter bee vs bumble bee vs carpenter ant
| Feature | Carpenter bee | Bumble bee | Carpenter ant |
|---|---|---|---|
| Abdomen | Mostly bare, shiny black 1 | Hairy, often yellow 1 | Ant body, pinched waist |
| Head width | Nearly as wide as thorax 3 | Much narrower than thorax 3 | n/a |
| Nest | Drilled galleries in bare wood 1 | Not in drilled wood holes | Damp or soft wood |
| Sign | Round 1/2-inch hole 5 | No drilled hole | Coarse sawdust, no round hole |
See our pages on the bumble bee and the carpenter ant for those insects.
Common carpenter bee myths
How carpenter bees vary by region
Ohio State says carpenter bees have one generation a year in northern states and sometimes two in southern states 3.
The eastern carpenter bee ranges across the eastern U.S. south to Texas and northern Florida, while Xylocopa micans runs from southeastern Virginia down the coast to Florida and west to Texas 4.
In Nebraska, Extension reports most activity from May through July 5. Expect a longer season, and possibly a second brood, in the South.
What to do about carpenter bees at your house
Hovering bees with no holes need no action beyond painting bare wood. A few new holes can be plugged in fall and painted over, while many holes, high eaves or soft wood call for a professional and a carpenter.
Ask any company whether it will plug and seal holes as well as treat them, and how it limits harm to pollinators. Our guide to choosing a pest control company has more questions.
- If Bees hovering, no holes
- Then Watch; paint bare wood
- If A few holes in reachable wood
- Then Plug in fall, then paint 1
- If Holes high on eaves or many holes
- Then Call a professional
- If Soft, tunneled boards
- Then Call a carpenter to repair
Source: [1]
Quick decision guide
With no holes, paint and watch. With a few holes, plug and paint in fall. Many or high holes need a professional, and soft wood needs a carpenter.
Questions about Carpenter Bee
How do I tell a carpenter bee from a bumble bee?
Look at the abdomen. A carpenter bee’s abdomen is mostly bare and shiny black, while a bumble bee’s is fuzzy and often has yellow hair, according to Penn State. Ohio State adds that a carpenter bee’s head is nearly as wide as its thorax, while a bumble bee’s head is much narrower.
Do carpenter bees sting?
Male carpenter bees cannot sting, and females rarely do. Penn State says males only hover and dart near nests. Ohio State says females can sting more than once but are docile and sting only when handled. People with bee sting allergies should still avoid handling them and seek emergency care for severe reactions.
What do carpenter bee holes look like?
Carpenter bee holes are perfectly round, about 1/2 inch across, and drilled into bare wood such as eaves, decks, fascia and railings. Coarse sawdust or yellow frass often collects below. The tunnel goes in about an inch, then turns at a right angle and runs along the grain.
How much damage do carpenter bees cause?
A single carpenter bee causes only slight damage, but repeated use over years can cause considerable damage, Penn State and Clemson say. Galleries usually run 4 to 6 inches, but when reused by many generations they can reach 10 feet.
What is the best way to keep carpenter bees away?
Paint is the best defense. Clemson calls oil-based paint or polyurethane on exposed wood the most effective deterrent, and Ohio State says to check the paint regularly. Stains give little protection. Plug old holes in fall so returning bees cannot reuse them, and consider pressure-treated wood for new projects.
When are carpenter bees active?
Carpenter bees become active in spring. Clemson and Ohio State say adults emerge in April and May. Nebraska Extension reports most activity from May through July. New adults appear in late summer and return to the tunnels to spend the winter, so you may see them again in August.
Should I fill carpenter bee holes right away?
Not if the hole has just been treated. Penn State says not to plug treated holes right away, so bees carry the dust into the tunnel, and Ohio State says to wait a few days.
Then plug with a dowel and wood glue or wood putty and paint. Penn State suggests plugging and finishing in fall.
Are carpenter bees good for anything?
Yes. Carpenter bees are important flower pollinators, according to Ohio State and the University of Nebraska. That is why extension guides focus on painting wood and plugging holes first. Keeping them off your house protects the wood without removing a useful native bee from the area.
Sources
- Penn State Extension, Carpenter Bees, retrieved .
- Clemson Cooperative Extension HGIC, Carpenter Bees, retrieved .
- Ohio State University Extension, Carpenter Bees (HYG-2074), retrieved .
- UF/IFAS Extension, Large Carpenter Bees, Xylocopa spp. (EENY-100), hosted by Texas A&M, retrieved .
- Nebraska Extension (Douglas-Sarpy), A Bug’s Life: Carpenter Bee, retrieved .
Expert review
Written by the HyrePest Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Identification, nesting, gallery measurements, life cycle and prevention follow Penn State, Clemson HGIC, Ohio State HYG-2074, UF/IFAS EENY-100 and Nebraska Extension, attributed to each. No prices, application rates or product names are given.
Suggest a correction. We fix errors and say what changed.