Field plate · Xylocopa virginica
Carpenter bee
A big, loud bee hovering at the eaves each spring, and a neat round hole in the deck rail to show for it. Common, mostly cosmetic — and routinely sprayed by mistake for its near-twin, the bumblebee.
Plate 24 of 28. Drawn in profile to the identification marks named below; the scale rule is a drawing convention — sizes are given in the text.
Identification marks
About 20–25 mm, glossy black, with a bare, shiny abdomen — that naked black rear end is the field mark. The thorax is fuzzy and yellow-brown. Males hover and bluff at face height but cannot sting; females can sting but very rarely do. The other evidence is the hole: a clean, round entrance about 12 mm across in bare or weathered softwood, often with coarse sawdust below it.
Look-alikes it is confused with
Bumblebees — which are fuzzy all over, abdomen included, live socially in ground or cavity nests, and should be left alone as the pollinators they are. If the abdomen shines like polished plastic, it is a carpenter bee; if it wears a fur coat end to end, it is a bumblebee. Also confused with carpenter ants (no wings on the workers you see indoors, and the sawdust and damage patterns differ).
Where it hides in a house
Not in the house — in the wood of it: deck rails and joists, fascia and eaves, fence posts, wooden benches, and unpainted softwood trim. The female bores a short entrance, then turns and tunnels along the grain, partitioning cells for her young. Old tunnels are reused and extended year after year, which is where the real damage accumulates.
Health & property risk, stated plainly
The sting risk is minimal. The wood damage is usually cosmetic and slow — a gallery a season — but repeated reuse over years can weaken a rail or fascia board, and the holes invite woodpeckers, which do far louder damage enlarging them. Carpenter bees are also pollinators; this is a pest to manage at the wood, not to wage war on.
What actually works
Prevention at the surface: paint or varnish exposed softwood (bees strongly prefer bare, weathered wood), and seal old holes in autumn — after the bees have left — with dowel and filler so they are not reused. For active holes in season, a labeled dust applied into the gallery is the standard professional treatment; treat, wait, then plug. Hanging traps catch some foragers but do not protect the wood by themselves.
What doesn't
Spraying every bee you see in April (the hoverers are males, and more will come), sealing an active hole in spring with the bee and her brood inside (she will bore a new exit, sometimes into worse places), and treating painted, sound wood that has no holes.
When to call a licensed pro
When holes are high on fascia or gables, when galleries have been reused for several seasons, or when woodpecker damage has started. Ask for the galleries to be treated and then plugged — in that order.