Carpenter bees don't feed on wood, but they nest in it. Unfortunately, the bees reuse old nesting sites, and they will come back every spring in greater numbers once they decide they like your property. Their reuse of nesting sites can cause significant damage to the wood over time. Get rid of carpenter bees by making your property as unattractive as possible to them instead of killing them.
Build with Hardwoods
When building fences, sheds, mailboxes, decks and other wooden structures in your lawn and garden, use hardwoods rather than softwoods. Carpenter bees are less attracted to hardwoods than softwoods because they are more difficult to burrow into, making it harder to nest.
Keep Outbuildings Closed
In spring, many homeowners begin gardening and tackling outdoor projects, leaving wooden garages and sheds open while they do so. Unfortunately, spring is also the time when carpenter bees actively search for nesting sites. Keep your wooden outbuildings closed during spring to prevent bees from finding their way inside them. Carpenter bees are resourceful, drilling into interior walls, wooden table legs and wooden ladders. Keeping them out of your storage spaces will prevent them from nesting there.
Another way to prevent carpenter bees from nesting is to paint every piece of exposed wood on your property with an oil-based or polyurethane-based paint. It is important to paint everything, including the places not usually visible, such as under wooden windowsills. Carpenter bees prefer unfinished wood, and paint acts as a deterrent.
Plug Old Nests
Because carpenter bees reuse old nests, find and plug those nests. Look for perfectly round holes in wooden structures in spring when the bees are active. The holes are often accompanied by a pile of fresh sawdust, and an aggressive-looking bee may hover near nest entrances. When you find a hole, make a note of its location. Then seal it in midsummer with a piece of steel wool and caulk.
Build a Decoy
If you have trouble convincing the bees to stay away, try luring them to a sacrificial piece of wood -- a hanging piece of softwood, such as redwood, cedar, cypress or pine. Ensure that wood decoy has overhangs like a roof does because the bees will be drawn to that feature. Place the wood decoy as far as possible from the wood you want to protect, and leave it bare rather than painted or stained. With any luck, they bees will prefer that wood to the other wood on your property.