Carpenter bees are common in residential areas, often causing concern for homeowners. These insects are frequently observed buzzing around wooden structures, sometimes leading to confusion with other types of bees. Understanding their characteristics and behaviors helps manage their presence around homes.
What Are Carpenter Bees?
Carpenter bees are large, robust insects measuring 0.5 to 1 inch in length. They are identified by their shiny, hairless black or metallic blue-black abdomens. Their thorax, or midsection, is often covered with yellow, orange, or white fuzz. These bees get their name from their habit of boring into wood to create nests, a behavior carried out by the female.
Female carpenter bees chew round holes, about 0.5 inches in diameter, into wood. These holes extend a short distance into the wood, then turn at a right angle to run parallel to the wood grain, forming tunnels or galleries. Carpenter bees are solitary insects, meaning each female builds and manages her own nest, unlike social bees that live in large colonies.
Distinguishing Them from Other Bees
Carpenter bees are often mistaken for bumblebees due to their similar size and appearance. A primary distinguishing feature is the abdomen: carpenter bees have a smooth, shiny, mostly hairless, typically black abdomen. Bumblebees, in contrast, have a fuzzy abdomen, often with yellow or other colored markings.
Nesting habits also differ significantly. Carpenter bees bore into wood for nests, while bumblebees typically nest in the ground, often in abandoned rodent burrows or other cavities. Male carpenter bees are known for territorial flight, often hovering aggressively, but they cannot sting. Female carpenter bees possess a stinger but are generally docile, stinging only if provoked or handled.
Damage They Cause
Carpenter bees damage wooden structures by excavating tunnels for nesting. The entry hole is distinctively round, about 0.5 inches in diameter, appearing as if drilled with a power tool. After entering the wood, the bee turns and extends the tunnel along the wood grain, creating galleries 6 to 12 inches long, sometimes up to 10 feet with repeated use.
As they bore, carpenter bees push out sawdust-like frass, which often accumulates below entry holes. They also excrete sticky, yellowish waste that can stain surfaces in a fan-shaped pattern, which may turn black with mold. While a single nest may not cause significant structural issues, repeated infestations and tunnel enlargement over several years can weaken wooden components. This damage can affect fascia boards, eaves, decks, and other wooden elements, potentially leading to cosmetic issues, water infiltration, and attracting woodpeckers who seek out bee larvae, causing further damage.
Managing Carpenter Bees
Managing carpenter bees involves preventative measures and direct control. Prevention is important, as carpenter bees prefer to bore into unfinished, unpainted, or weathered wood. Regularly painting or varnishing exposed wood surfaces deters nesting. Using harder woods or non-wood materials like vinyl or aluminum siding also makes structures less attractive.
Sealing existing cracks, depressions, and old holes with caulk or wood putty prevents bees from using them as starting points. For active infestations, apply insecticidal dusts containing pyrethroids or boric acid directly into entry holes, ideally at night when bees are in tunnels. After treatment, wait a few days to ensure bees contact the insecticide before sealing holes with wood putty or dowels. Carpenter bee traps are also available to lure and capture bees. If the infestation is extensive or involves hard-to-reach areas, consulting a professional pest control company is beneficial.