Wood bees, or carpenter bees, are common household pests that damage wood by drilling into it to create nesting sites for their young. The female bee uses her mandibles to bore a half-inch hole, then excavates a long tunnel, called a gallery, running with the wood grain. These tunnels weaken wooden structures and attract woodpeckers seeking larvae, worsening the damage. Homeowners can use specific repellents and modifications to make wooden surfaces undesirable for nesting.
Scent and Oil-Based Repellent Applications
Carpenter bees possess a highly developed sense of smell, and strong odors act as non-toxic deterrents by disrupting their navigation. Essential oils are frequently used, with peppermint oil being effective due to its intense menthol scent. A common application involves mixing 10 to 20 drops of pure oil with water and soap in a spray bottle, then applying it to vulnerable wood surfaces.
Citrus scents, derived from fruits like lemon, orange, and lime, are equally repulsive. Homeowners can create a simple citrus spray by boiling fruit peels in water and applying the cooled solution to decks, eaves, and railings.
Another natural repellent is almond oil, which contains Benzoaldehyde that bees actively avoid. Almond oil offers longer protection, maintaining its effects for up to three or four months. For existing holes, a cotton ball soaked in a concentrated essential oil like tea tree or eucalyptus can drive out current occupants. These topical applications require reapplication, especially after rain, to sustain the necessary odor concentration.
Physical and Visual Deterrent Strategies
Methods that confuse the bee’s senses or nesting instincts offer an alternative to applied repellents. Carpenter bees are highly sensitive to vibrations and loud, persistent noise, which makes an area unattractive for nesting. Hanging wind chimes near active areas creates an irritating, unpredictable environment that encourages relocation.
Visual cues are also effective deterrents. The reflection from shiny objects, such as compact discs (CDs) or strips of aluminum foil, creates a flashing distraction that confuses the bees’ eyesight and flight path. Attaching these reflective items to eaves or rafters can prevent them from settling.
A third strategy is to mimic the presence of a natural enemy. Carpenter bees avoid areas where they perceive a threat from stinging insects like wasps or hornets. Hanging a fake wasp nest, typically a simple inflated paper bag, tricks the bees into believing the territory is occupied and too dangerous for them to nest.
Wood Surface Modification for Prevention
The most effective long-term deterrent involves altering the wood itself to make it physically inaccessible or chemically unappealing. Carpenter bees overwhelmingly prefer unpainted, untreated softwood like pine, cedar, or redwood because it is easier to chew. Applying two coats of paint or a polyurethane sealant creates a hard, physical barrier that significantly discourages drilling.
These coatings cover the wood grain, making it difficult for the bee to recognize the material as a suitable nesting site. While wood stains offer less protection, oil-based exterior finishes and polyurethane sealants provide a durable coating the bees are less willing to penetrate. For new construction, using naturally dense hardwoods like oak or maple, or selecting pressure-treated lumber, makes the material physically resistant to boring.
For wood that is already infested or difficult to paint, a borate treatment, such as a solution containing boric acid, offers a deep-penetrating, long-term solution. When applied to bare wood or sprayed into existing galleries, borate compounds alter the wood’s composition, making it toxic and indigestible to the bees and their larvae. This modification transforms the wood into a material that the bees will subsequently avoid.