Carpenter Bees Are Drilling Your Deck. Here's the Damage You Can't See

Back to all articles

That Hole Is Too Round to Be an Accident

If you have found a hole in your deck rail, fascia board, pergola, or the underside of a windowsill that is almost perfectly circular and about half an inch across, that is a carpenter bee entrance. Nothing else in a Long Island yard makes a hole that neat.

What you cannot see is what happens after the entrance. The bee drills straight in for an inch or so, then makes a sharp turn and tunnels along the grain, sometimes four to six inches, occasionally much further. She partitions that gallery into cells, provisions each with pollen, lays an egg in each and seals it.

The Damage Compounds Every Year

Carpenter bees do not eat wood. They excavate it, which means a single season of activity is usually cosmetic. The problem is what happens over time.

New generations return to the same wood, and reusing an existing gallery is far cheaper than drilling a new one. So they extend it. A board with ten years of activity can have a branching network of tunnels running through it, and the structural loss becomes real. Deck rails and pergola beams are the most common places where this eventually matters.

The Woodpeckers Are the Bigger Problem

This is the part homeowners rarely anticipate. Carpenter bee larvae sealed inside a gallery are a concentrated, high-value meal, and woodpeckers know exactly how to find them. A woodpecker will open the gallery along its length, turning a half-inch hole into a long ragged trench in a single afternoon.

More often than not, the expensive damage on a carpenter bee job was done by a bird, not by an insect.

The Hovering One Cannot Sting You

Carpenter bees have a reputation for aggression that they do not deserve. The bee that flies at your face and hovers a foot away while you are trying to grill is a male. Males are territorial and confrontational, and they are also physically incapable of stinging. They have no stinger.

Females can sting and will if handled or trapped against skin, but they are focused on excavating and provisioning, and stings are uncommon. If you have been dive-bombed on your own deck every spring, that has been a bluff.

What They Choose, and What They Skip

Carpenter bees strongly prefer bare, weathered, unfinished softwood. Cedar, redwood, pine and fir are all favorites. They generally avoid wood with a hard painted finish, and they are less interested in well-sealed stained surfaces.

This gives you a genuinely effective non-chemical option: paint the vulnerable surfaces. Fascia, rail caps, the underside of deck rails and the exposed ends of pergola beams. A hard exterior paint is a meaningful deterrent in a way that a light stain is not.

Do Not Just Plug the Hole in June

A common mistake is caulking or dowelling the entrance as soon as it is spotted. If you seal a gallery with developing larvae inside, they generally chew their way out through the surrounding wood, so you get new exit holes and slightly more damage.

The sequence that works is to address the gallery first and seal it afterward, once activity is finished for the season, then paint the surface so the next generation looks elsewhere.

How We Handle It

Carpenter bee work is treatment of the galleries themselves, timed to spring emergence when the bees are active and the tunnels are shallow, followed by exterior treatment of the surfaces they favor. Nest and web removal from accessible exterior surfaces is included at every visit under a recurring plan.

Keep people and pets off treated surfaces until dry, about 30 minutes.

See how our stinging insect service works →