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

  • DIY Carpenter Bee Trap (article)
  • Carpenter Bees (North Carolina State University)
  • Carpenter Bees (University of California Integrated Pest Management)

40 COMMENTS

  1. 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. 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?

  3. 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…………..

  4. 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????

  5. 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?

  6. A handyman told me this trick, which has worked for me: spray WD 40 into carpenter bee holes in the late summer/early fall, then fill the holes and paint. He said the WD 40 burns up the larvae and the bee, if there is one. I didn’t realize they turn their tunnels once they are inside the wood, and I like the idea of using steel wool, etc. to fill the hole

  7. I have a real problem they are drilling holes under my shed. They have been coming here for almost 2 years. I can’t get under the shed to fill in holes it’s to low to the ground. Can someone tell me what I need to do?

  8. Lots of questions. Where are the answers? If I plug a hole with steel wool, will the larvae dig their way out and cause more damage? Will any adult bees inside dig their way out? Or will they die before doing so? Other sites say caulk is useless; they’ll drill through it. So why is this site recommending caulk?

  9. After doing research, I like this idea. Spray hole at night with carb. cleaner, and fill with steel wool. Carb cleaner, I understand, will kill the bee and the larvae. If the bee is not present at time of spray, it won’t be able to get back in because of steel wool. Larvae, if alive, won’t be able to get out. Next evening, fill the hole with caulk or wood putty once it is dry. After this dries, if divot develops, apply a second coat. Paint. I’m doing this tomorrow night. Feel free to ask me questions on whether or not this worked. Best to all.

  10. i have what looks like a carpenter bee living under my deck. They swarm like crazy. They are fat and furry also. I can not seem to get them to leave. I’ve have an exterminator come out and they don’t seem to be able to get rid of them. Any help would be appreciated.
    Terri.

  11. I’ve learned that getting rid of carpenter bees requires a multiple approach. You need to use both carpenter bee traps to quickly reduce the population you’re dealing with and then insert a pesticide or natural agent such as diatomaceus earth directly into the entry hole and into their tunnels. Best done in late summer once the larvae have developed. Finally, plug with steel wool and caulk or glued wooden plugs.

  12. If you have bees living under a shed or in the ground or even other areas for that matter, the following works very well. Once you know the entry exit point of those pest put some Seven’s dust over the hole. This is dust you would use on vegetables in your garden. It will kill all bees in 24hrs. As they will file through this and take it back to the nest to aid in killing those. You can also place it in a dried ketchup bottle and shout it down the hole if needed. But I have found that a nice little pile at the point of entry does the trick. Keep pets away from this area until you can wash away the product after a few days. This has never failed me however I have used products with a different name without getting the results I do with the brand name Sevens.

  13. We had some water damage in our bay window on the second level of our house, a few years ago. The problem with the window was fixed but this year the underside is filled with small bees. For about a month I have occasionally found dead bees on the wide window sill inside of the window. Today I found a small pile of sawdust-like material on the floor inside under the windowsill. I have not found an entrance hole but see above that they can get into vinyl window frames! Would spray but not sure where to spray?

  14. Spray WD-40 into hole. Then plug with sections of smaller than one half inch wooden dowel rods. Use exterior carpenter glue. In April and May, use carpenter bee spray. Soak infected areas each month. They can get indoors, so spray the bottoms of them also.

  15. Carpenter Bees were damaging the overhead wood and posts on my patio. I painted everything white and have not had problems in 2 years. I read that white paint is a deterrent.

  16. These bees keep flying around our trampoline. So every time we try to go out there they try to get us to leave. I have no idea why they would want a trampoline but they seem very interested in it and won’t leave. Is there anything I can do to get them to leave? like spray because there is no wood on our tramp.

  17. i have a carpenter bee problem
    the are under my shed but i cant access the wood. should i place
    a metal skirt around the shed and will that stop them

  18. They are impossible to get rid of! They ignore the traps and the shower in thebug spray and fly off. I pluged the holes added steelwool filled the entrance and painted. You would never know. All the holes are back you would think I did nothing. Im going to try wasp and hornet spray once a week for the rest of the summer. We will see what that does. The damn things are 30 to 40 feet high.
    I have an old tudor. The problem is recent.

  19. DW-40 will do the job. It’s the only thing that worked for me. Spray the wholesale and wait 1 hour. Start counting the bees that will fall off dead.

  20. I’ve read that carpenter bees do not like hard woods, and painted surfaces.
    The experts say their favorite woods are: redwood, cedar, white pine, and southern yellow pine. The females chew perfectly round holes into the wood, down for about an inch and then drill horizontally along the grain for about 4-6 inches. They deposit their eggs in chambers they create in these tunnels. My theory: Purchase bare, untreated and unpainted boards at least 2×4 inches in dimension. Leave them outside to weather and make them more attractive to the females who do all the tunneling. Around the first of March, place these boards strategically around your property. Hang a sign on them, “Carpenter Bees Welcome. Rent Free.” At the end of the summer, I’m thinking these boards will have a number of carpenter bee holes in them, with the baby bees who will emerge next March. At some point before the end of the year, take these boards some distance into the woods and leave them there. (I hate to kill critters.) Since experts say they hatched bees tend to return to their homes, they will now come back to the same holes from which they emerged, you’ve exported your problem. Make sure you place new boards on your property for the next generation of carpenter bees. That’s my theory and I’m sticking with it.

  21. I used carb cleaner and anything my husband had in the garage to spray every hole in the wood awning. I then used cement for the holes. well to my surprise you hear them drilling to get out so I guess the best is father then I thought when spraying. Took them couple of days and there back. I don’t know what else to do but can’t afford to take it down since it’s needed for shade. Any suggestions out there. I’m so done with bees

  22. my dog dug 2 holes in the deck the wood is gray on outside but inside the wood is dark red does anyone know why this is ?

  23. This is the second year I have noticed carpenter bees. Each time I thought I had gotten rid of them by spraying, but here is the situation: Over the garage I have painted cedar shingles over unpainted boards. Lately I notice, when I open the garage door, that fine sawdust is “sprinkling” down from between the (overlapping) gaps of the shingles. What would be my best approach to treat these pests. What should I expect an exterminator to do?
    Thank you. Your web page information is really helpful for understanding the issue.
    Herb Bauer

  24. I need help. I have carpenter bees in my wood pile. I have used wasp spray, boric acid, seven solution that I poured in a pvc pipe that I put in where I saw them coming out of. They keep coming. Would a smoke bomb work. I can’t get close to the area to cover or remove some of the wood. Any ideas??

  25. We have had carpenter bees boring into our patio roof and have tried spraying them with flying wasp and hornet spray and nothing is working to get rid of them. Please help…..they are now chewing the wood besides the females boring holes. What else can we do besides painting the wood..????

  26. Use traps….on ebay for about $16 for 4. Works great.
    Also, I use Permethrin SFR 36.8%…Mix about 2 ounces per gallon. Will rid area of most bugs including your wood boring bees….spray all exposed wood.

  27. Just provide an easy alternative for the bees. We keep soft wood tree stumps with the bark on off to the side of our patio. They love it, and stay out of our wood decking.

  28. We spray brake fluid into the holes left by the bees. I have about a dozen daily outside my back door. The brake fluid works instantly.

  29. Thank you for such an informative article! Although my husband had assured me the male boor bees won’t sting, seeing that statement in print was comforting, lol. We have one every year that loves to dive bombs me and intimidate me by buzzing loudly and staring me down while hovering or flying within 3 feet. He’s behind my back trying to scare me now as I write this! No more fear!!! Thank you!

    • Hi, Judi,

      We are so happy to hear that you enjoy “Today’s Homeowner!”
      If you haven’t already, please…

      *Follow us on Facebook: https://www..com/todayshomeownermedia/
      *Like us on Twitter: https://.com/DannyLipford
      *And check out Instagram and Pinterest pages! (https://www..com/todayshomeowner/ and https://www..com/todayshomeowner/pins/)

      And we always appreciate when our fans tell their friends about the practical home improvement advice they receive from “Today’s Homeowner.”

      Thanks so much for watching — take care!

  30. I had some persistent ones so I sprayed was/yellow jacket spray into their hole. Two years later it was still killing the new arrivals.

  31. Elizabeth asks:
    August 21st, 2016 at 9:01 pm
    “Would a smoke bomb work””

    Elizabeth:
    I think it would work fine once all the wood burns up from the fire you started.

  32. its sad to hear the only comments people think of sharing are to kill them. i dont want to kill them, i just want to deter them . im going up north to gather some soft wood trunks and will place them in the corner of the yard hopefully inviting them to nest in those vs my deck

LEAVE A REPLY