Home Improvement Expert Danny Lipford

How to Deal with Carpenter Bees

Carpenter bee flying

Carpenter bee with shiny black abdomen.

Chances are you’ve been buzzed by a large, intimidating-looking bee when working on the outside of your home. You may also have the telltale holes in your woodwork where these bees build their nests.

About Carpenter Bees

Carpenter bees are large black and yellow bees that resemble bumblebees. But while bumblebees are fuzzy all over; carpenter bees have a large, shiny, solid black abdomen.

While they may look scary, male carpenter bees – the ones most likely to dive-bomb your head with a whitish spot on their face – don’t even have stingers, and females generally won’t sting unless you aggravate them.

Carpenter bees get their names by the perfectly round, half-inch or so diameter holes that they drill in wood for their nests. In the spring, the bees emerge from their winter nests, mate, and set about building this year’s nest.

The female bee uses sharp teeth to excavate a perfectly round tunnel in soft wood, or she may choose instead to remodel an existing tunnel. She then lays her eggs in the tunnel, where they develop as her life cycle comes to an end.

In late summer, the new bees emerge to feed on plant nectar, then crawl back into their hole for the winter.

Carpenter bee inside hole in wood

A closer look at a hole in wood shows carpenter bee inside.

Carpenter Bee Damage

Carpenter bees prefer to excavate their nests in soft, unpainted wood – such as the back side of fascia boards, siding, window trim, and porch ceilings. They also bore into decks, outdoor furniture, fence posts, and swing sets. Softer woods – like pine, cedar, redwood, and cypress – are more attractive for nests while treated lumber and hardwoods are less inviting.

The holes typically go inward for about an inch, then the tunnel turns and follows the grain of the wood for about six more inches. The tunnel might branch into smaller ones that are shared by multiple bees.

In addition to tunnels, you might also find:

  • Fresh sawdust outside the hole.
  • Scraping sounds from inside the wood.
  • Fan-shaped stains outside the openings.
Hole in bottom of wood floor joist made by carpenter bee

Carpenter bee tunnel entry is usually underneath a board, or sometimes on the side.

If your infestation is limited to a tunnel or two, there’s nothing to worry about. Even though they technically do bore into wood, carpenter bees don’t systematically destroy a structure like termites or carpenter ants.

However, if the infestation is extensive or has been going on for years, the sheer number of tunnels can cause problems, including:

  • Structural Damage: It would take a lot of tunnels to compromise a structure, but over time they can weaken wood.
  • Water Damage: If moisture enters the tunnels, it can speed the rotting of the wood. This is especially problematic if the tunnels are in your home’s siding, since it protects the structure.
  • Stains: Feces of carpenter bees can stain wood.
  • Woodpeckers: Insect eating birds can be drawn to the enticing sounds of bee nesting and larvae, which can invite much more severe damage.

How to Prevent Carpenter Bee Damage

Here are some tips for making your home less attractive to carpenter bees:

  • Paint or Varnish: You can discourage carpenter bees by painting all surfaces (including the backs and undersides of boards) with a sealing primer and at least two coats of paint. Stains and varnishes are less effective, but any coating is better than bare wood.
  • Treated or Hard Lumber: Treated lumber and hardwoods are less susceptible to damage from carpenter bees.
  • Non-Wood Covering: If the problem is unrelenting, you may need to look into non-wood siding and trim options, such as aluminum, vinyl, fiber cement, or masonry.
  • Fill Cracks: Before painting or sealing, fill all cracks, nail holes, divots, and splintered wood with caulking or putty; since these are attractive starting places for bees.
Caulking hole made in wood by carpenter bee

Seal holes after treating, followed by paint

How to Deal with Carpenter Bees

If the bees are already at work on your home:

  • Fill Abandoned Holes: When carpenter bees emerge in spring and again in fall, fill holes with a bit of steel wool, a wad of aluminum foil, a dowel and wood glue, or even caulk. After filling the holes completely, paint over them.
  • Treat Active Holes: If the holes are still active, you may want to treat the holes with a targeted dose of insecticide first. Products such as pyrethrum, boric acid, carbaryl (Sevin), or any spray labeled for flying insects will do the trick. The best time to treat the holes is at night when bees are resting, or in early spring while they’re still hibernating. Apply the spray or powder directly in the hole, staying on alert for an angry female bee that might emerge. By the next day, you should be able to fill and paint over the tunnel.
  • Avoid Wood Treatments: Since carpenter bees don’t actually eat wood, treating it doesn’t do much good.
  • Stay Alert: There’s no way to completely prevent or eliminate carpenter bees. But by taking these steps and staying alert to new activity, you can keep damage to a minimum.

Further Information

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7 Comments on “How to Deal with Carpenter Bees”

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  1. Terry Says:
    June 29th, 2013 at 2:10 pm

    I have what look like bees in holes in the morter of my chimminy. It was a cool day and while on the roof noticed a number of holes in the morter with what looked like the back end of a bug in it. I poked it with my ever handy swiss army knife and it backed out turned around and backed into the hole. The tail is striped and it was slimmer than a carpenter bee. What gives? Is this some new killed bee from asia that can bore into concrete? I smell a new movie.

  2. Eileen Gunning Says:
    August 5th, 2013 at 4:17 pm

    Carpenter bees are now drillingholes into the vinyl window frames!

  3. Dee Says:
    August 12th, 2013 at 12:50 pm

    I have noticed some small bee-like pest that are yellowish in color & winged. They are nesting in the underside of my patio door frame, & they seem to attack this space if disturbed. Along with these tiny bee’s, I have noticed that there are ‘crumbling of concrete/mortar’ that is fine granules right below the door frame on a daily basis. What sort of Bee’s eats away at concrete or mortar & how do I get rid of these pests, because they have attacked my dog & have stung him & my dog now refuses to eat his food on the patio for fear that he’d get stung again. Will spray chemicals under my door-frame kill these pests?

  4. Help Says:
    May 26th, 2014 at 11:21 am

    We know we have carpenter bees in our gazebo. We are trying our best to get them out. But my main question is our screens start to have little holes appearing when we just changed them out. And this morning there was a carpenter bee inside. Could this be the reason. Are they That stupid that once they get in the gazebo they don’t know how to get out, so they try eatin( their way out through the screen. This drives me crazy. Other bees woulda remember how they got in and then get back out again. I can see eating the wood but screen too. Help…………..

  5. Nancy Pahor Says:
    July 31st, 2014 at 10:33 pm

    We have Carpenter Bees that hang out in our yard in Hawaii around our wood yard furniture..
    They don’t seem to be eating the wood, but what they are doing is picking at our black out door furniture cushions!!!!
    Very strange.
    So we now have lines and lines of pulled snags marks on all our outdoor cushions. It’s as if they are collecting bits of of the cushion to make a nest or something! Sometimes there is even a bit a residue on the cushions….could they be trying to make a nursery in the cushion????

  6. Marjorie Lamb - Ireland Says:
    September 12th, 2014 at 3:33 am

    I am trying to find out what is grinding up cement at the base of our house. There seems to be a tiny hole and all that I see is a teaspoon or two of perfectly ground up cement being ejected from that hole. I have swept it up on more than one occasion and it keeps coming back. Any ideas?

  7. Leslie Boone Says:
    March 29th, 2015 at 5:10 pm

    carpenter bees are coming from under my storage house. How can I get to them?

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