Effectively harmless. The one that hovers in your face and looks threatening is the male, and he has no sting at all. Females can sting and essentially never do unless handled.
Size20–25 mm
MarkingsShiny, hairless black abdomen — this is the character that separates it from a bumblebee · Furry yellow thorax, so it looks like a bumblebee from the front only
WhereUnpainted softwood — fascia boards, deck rails, fence posts, eaves, garden furniture. Forages on flowers.
SeasonActive spring to late summer; most conspicuous in spring
How to tell it apart
Shiny, hairless black abdomen — this is the character that separates it from a bumblebee
Furry yellow thorax, so it looks like a bumblebee from the front only
Males have a pale yellow patch on the face; females have a solid black face
Perfectly round 12 mm holes in bare softwood, often on the underside of a board
Hovers in one spot, then darts, then returns to the same spot
Where you’ll find it
The eastern and central United States, with other Xylocopa species in the west.
Unpainted softwood — fascia boards, deck rails, fence posts, eaves, garden furniture. Forages on flowers.
Active spring to late summer; most conspicuous in spring.
How it behaves
The alarming behaviour is entirely male display. He holds a patch of air near the nest, confronts anything that enters it including people, and is incapable of stinging. Meanwhile the female bores a round entrance hole into bare wood and tunnels along the grain to make brood cells. She is not eating the wood — it is excavation, and the sawdust beneath the hole is the giveaway. Tunnels get extended and reused year after year, which is how the damage becomes structural over a long time rather than a season.
You’ve found one indoors
Paint or varnish bare softwood — they strongly prefer unfinished wood and finishing it is the only measure that reliably works long-term. Filling holes in autumn, once they are vacated, stops them being reused. They are good pollinators and killing them is rarely the right response to what is a slow, localised problem.
Common questions
Do carpenter bees sting?
Males cannot — they have no sting. Females can and almost never do; it takes handling or trapping one against skin. The bee flying at your head is the male.
How do I tell it from a bumblebee?
The abdomen. A carpenter bee's is shiny, black and bare; a bumblebee's is furry and usually banded. From behind they are unmistakable; from the front they look almost identical.
Will they destroy my deck?
Not quickly. Damage accumulates over years of reuse and expansion rather than in one season. Painted wood is largely ignored.
What are the sawdust piles under the holes?
Excavated wood. They do not eat it — they tunnel through it to make brood cells and push the debris out behind them.
Leila Dasher · CC-BY