Managing Carpenter Bees in Wood Siding Organically

Perfectly round, 1/2-inch holes in vinyl or wood siding with yellowish-brown stains below are the signature of carpenter bees (Xylocopa spp.). These large, shiny-black bees (males have a yellow face patch) bore galleries to lay eggs, not to eat wood.

Organic Control Options

• Pyrethrin or Rotenone dust: Puff into active holes at night (when bees are inside). Seal holes with wood putty or caulk 24 hours later. Both are plant-derived and break down quickly.
• Bee traps: Wooden boxes with pre-drilled holes and a collection jar exploit the bees' nesting instinct. Hang near active areas. Empty periodically.
• Prevention: Paint or polyurethane all exposed wood surfaces. Stains don't deter them. Consider non-wood materials (vinyl, fiber cement) for replacements.

Know the Difference

Carpenter bees resemble bumble bees but have a bare, shiny abdomen. Bumble bees are fuzzy all over and nest in the ground. Male carpenter bees are territorial but lack stingers; females sting only if handled.

When to Act

Spring (April–May) is peak nesting. Treat early to prevent gallery expansion. Unchecked, successive generations can weaken structural wood over years.