Carpenter bee

What carpenter bees look like

Carpenter bees are large, around 20 mm long, and at a glance they pass for bumble bees. The giveaway is the abdomen. On a carpenter bee the top of the abdomen is bare, shiny and black, almost like polished plastic, while a bumble bee is furred all over. The thorax is still hairy and usually yellow. Males have a pale or yellow patch on the face, hover in one spot and will fly straight at anything that comes near, but males have no sting at all. Females are darker faced, can sting, and rarely do. Flight is loud and direct, and you often see a single bee patrolling the same stretch of deck rail or fascia all afternoon. Unlike bumble bees and honey bees, carpenter bees are solitary rather than social, so each female works her own gallery.

Signs you have carpenter bees

• Round entry holes. Almost perfectly circular bores about 1 cm across, looking drilled, in fascia, soffit, deck rails, pergolas, siding, fence tops and window trim.
• Coarse sawdust. Piles of pale, gritty shavings on the ground, deck boards or window sills directly under a hole.
• Yellow staining. Brown and yellow streaks running down from a hole, which is waste left by the bees inside the gallery.
• Hovering males. A single bee holding position near the eaves or the deck and darting at people and other insects that pass.
• Rasping sounds. A faint scraping or chewing noise from inside a board on a quiet day while a female is excavating.
• Woodpecker damage. Torn, ragged holes and long splits where birds have opened galleries to reach the larvae inside.

The woodpecker damage is often more costly than what the bees did on their own.

Why carpenter bees turn up around Ottawa and Toronto properties

Carpenter bees want bare, weathered, untreated softwood, and they want it in the sun. Cedar, pine, fir and spruce are all favoured. That points them straight at the features people build onto Ontario homes: decks and deck rails, pergolas, gazebos, arbours, fence caps, play structures, wooden swing sets, shed trim, soffit, fascia and window frames. South and west facing surfaces get worked first because they are warm through the afternoon. Properties in older Toronto GTA neighbourhoods, Ottawa suburbs with mature cedar decks and Hamilton homes with wood trim all see them. The key point is history. Females often return to the wood where they emerged, and they expand old galleries instead of starting from scratch, so the same rail or fascia board gets tunnelled deeper year after year until the damage becomes structural.

Are carpenter bees dangerous?

As a health risk, carpenter bees are minor. The male that flies in your face has no sting. The female has one and can use it repeatedly, but she is docile and will only sting if handled or trapped. Anyone with a sting allergy still needs to take it seriously, and a gallery over a doorway or a seating area is worth dealing with for that reason. The property risk is a different matter, and this is where carpenter bees differ sharply from honey bees and bumble bees. They excavate tunnels into sound structural wood, typically boring in across the grain and then turning to run 15 cm or more with the grain. Galleries are reused and extended each season, branching into networks that weaken rails, joists and trim. Moisture follows the tunnels, rot sets in, and woodpeckers open the wood further chasing larvae.

How to keep carpenter bees away

• Paint exposed softwood rather than leaving it bare. A hard painted finish deters them far more effectively than stain or clear sealer alone.
• Use hardwood, pressure treated lumber or composite material for rails, caps and trim on new deck and pergola work.
• Cap exposed end grain on rails, posts, fence tops and beam ends, since end grain is a favourite starting point.
• Fill last season’s holes with wood filler or dowel once the gallery is clear, then sand and paint over the repair.
• Inspect eaves, fascia and deck framing each spring, because activity starts as soon as the weather warms.
• Screen open soffit vents, gable ends and the undersides of decks and porches where bare wood is easy to reach.

Sealing and painting old holes matters most, because returning females look for existing galleries first.

How GO! Pest Control handles carpenter bees

• Inspection. We locate every active and abandoned gallery, check how far the tunnelling runs and note which timbers are structural rather than decorative.
• Treatment. Carpenter bees damage wood, so unlike honey bees and bumble bees these do get treated. We apply product directly into the galleries so the bees carry it through the tunnel network.
• Repairs advice. We tell you which holes to plug and when, what filler and finish to use, and which boards are worth replacing rather than patching.
• Follow-up. We come back to check for new bores, deal with returning females and confirm that the treated galleries are no longer active.
• Advice. We go over paint, material choice and seasonal timing so next spring’s bees find nothing worth drilling into.

We are licensed, insured and bonded, and we work in homes, apartments, condos and businesses across the Toronto GTA, Ottawa and Hamilton.

Common questions about carpenter bees