When carpenter bees tunnel holes in the wooden parts of your home, that's just the beginning of your pest problems. If they attack the house shingles or underside of your deck, you could be hosting other nuisances, including carpenter ants or fungus.
It's one of the things that makes carpenter bees a challenge for homeowners. There are no central hives as with other bees and wasps, just the tunnels they bore in anything that's made of wood on your property.
The holes that are formed by carpenter bees are significant - the holes are 1/2 inch in diameter and as deep as 1 foot, leaving plenty of space for a new generation of the bees to be laid in the spaces. Sometimes several bees will use the same entrance hole and bore individual galleries off the main tunnel. If the same hole is left open for several seasons, the tunnels could eventually extend several feet into the wood.
Because the bees don't ingest the wood they bore through, spraying those areas has little effect on them. Caulking the holes is a time-consuming effort and may not have a lasting impact. They're also best plugged at night when the pests are less active, but that makes it more difficult to find all the holes.
When the infestation becomes too much to handle, it's best to leave the pest management to experts like those at commercial services like Abell Pest Control. They'll evaluate the extent of your problem, devise a treatment plan and make recommendations to prevent the issue from reoccurring.
You'll know if the holes you're finding are in active use by the bees if there are fecal stains near the openings. You may also see bees hovering under eaves, gables and decks. Virtually any wood surface is endangered when carpenter bees are about, including porch and shed ceilings, railings, overhead trim, wooden porch furniture, dead tree limbs, fence posts, wooden shingles and siding, windowsills and wooden doors.
One of the continuing maintenance tasks that you can observe to stop carpenter bees from returning is to paint wood that's become weathered from the elements or is bare and untreated by stains or paint. The bees' target is bare, unpainted wood - preferably softwoods like pine, fir, redwood and cedar - and painting the wood is the simplest step you can take to discourage these pests.