Carpenter bees may be identified by a blue-black, green, or purple metallic sheen and hairless abdomen. They may also be yellow and black like the traditional bumble bee, but what sets the carpenter bee apart is its large size. The carpenter bee is typically ½" to 1" long.
Carpenter bees are solitary (not social) wood-burrowing insects. The female bores long tunnels (approx ½ inch in diameter) into dry, exposed wood and then divides these tunnels into galleries (or cells) where individual larvae will develop. Carpenter bee galleries may be anywhere from 4 inches to 12 inches for a gallery colonzied by a single bee, to nearly 10 feet long in a gallery colonized by several carpenter bees in succession. While the female tends the nest, the male carpenter bee hovers around the gallery entrance, chasing anything that comes near. Males lack a stinger and are harmless. The female carpenter bee does have a stinger, but rarely uses it. Nest openings are usually found on the underside of wood surfaces.
The female carpenter bee lays eggs in individual galleries in the Spring. By early summer, larvae and pupae develop in the closed cells, a process that takes about 3 months. Adult carpenter bees emerge from the cells in late summer, and return to the same tunnels to overwinter the cold winter months. The following spring, each new adult bee will mate, and the new females will make a nest of her own, completing the cycle.
Signs of Infestation
- Half-inch round holes in dry, unfinished wood, with piles of sawdust underneath
- Dirty yellow streaks of fecal matter staining the wood below the hole
- If a given hole is presently occupied, you will likely find the male buzzing around you when you are near that hole
- A single pair of carpenter bees (male and female) occupies each nest, however, several pairs of carpenter bees may build separate nests in the same wooden structure.
Basic Prevention & Control:
1) Prevent infestation of wood as much as possible by painting and varnishing unfinished wood suseptible to infestation.
2) Apply a liquid residual in early spring, when carpenter bees are most active looking for a nesting site. Cyper WP and Cyonara 9.7 both very effective residuals that can applied directly to wood surfaces with a 1 gallon sprayer.
3) Apply a residual dust, such as Delta Dust, deep into active galleries using a centrobulb duster. This dust will remains effective for several months so that when the carpenter bee larvae develop and emerge as new adults, they will pass through the dust and die.
4) Seal off holes with wood putty or plastic plugs after all bees have died, to prevent future reinfestatin.
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For more detailed information on Carpenter Bee control, see How To Get Rid of Carpenter Bees