Hot Topics: How to Get Rid of Carpenter Bees

A carpenter bee on wood.

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Original Post: Deck resurfacer to repel carpenter bees

SuperSquirrel Member

I have had recurring issues with carpenter bees at my deck and shed. I took care of them a couple years ago with insecticide dust in their holes (and plugged the holes), but they've come back to start chewing again. Right now, I plan to paint and use a repellent additive in the paint to see if that deters them. I know I could spray the wood with a residual insecticide, but I'd prefer to save that option for last.

Has anyone had any luck using a deck resurfacer, like BEHR Deckover or Rust-Oleum Restore, to create a physical barrier to the bees? Or will they chew through that like regular wood?

marksr Forum Topic Moderator

Carpenter bees are less likely to chew into painted/stained wood, but it's not something that will stop them. I don't know if the thicker coating of a deck restore finish will hinder them or not. Personally, I wouldn't apply that stuff to a deck! It will look nice for awhile, but once it starts to fail it will take a LOT of work to make it look nice again.

SuperSquirrel Member

So far on the deck they've only gone after the joists. The deck surface is below eye level when you're on the ground, so the joists are really only visible if you're going under it for storage or whatnot. I'd be willing to deal with ugly there, if it kept them from chewing through. Of course, maybe then they'd just move on to the posts and chew them up instead.

marksr Forum Topic Moderator

The bad thing is the bees don't just drill straight in. They turn and can hollow out multiple chambers across the board. They are less likely to eat pressure treated wood, but I have seen them do it.

SuperSquirrel Member

Oh, yes. When I was treating them before, I sent a puff of dust in one hole, and it came out another hole about a foot away.

If the paint and repellent combo doesn't work, I guess I'll just up the ante and use the insecticide. The deck coatings are more expensive than insecticide anyway, and at least I know the insecticide will work.

stickshift Group Moderator

I can only say that I've never seen anyone on this site (or another I frequent) be happy long-term with the 'resurfacer' products you mention.

joecaption Member

Get yourself some of this:

I mix some in a pump sprayer using hot water so it will dissolve faster and make sure it's really mixed up. The main ingredient is boric acid, which will kill a wide range of insects by dehydrating them, not poisoning them. Do not just spray it in the holes--spray down all the exposed wood.

Marq1 Member

I've had good luck with cans of hornet spray, applying a couple cans a couple times per summer. Eventually, whatever you apply gets washed off, so this is pretty easy!

PAbugman Forum Topic Moderator

Carpenter bees like overhead environments, which is why we sometimes see them under aluminum soffits, even though they can't drill through them.

The deck restorer stuff is an interesting idea since it will be out of sight. Otherwise, I've not met people happy with it. It would certainly change the composition of the exposed wood to the bees.

I've known of people to successfully use cut window screening stapled to the wood they want to protect. It’s not aesthetically pleasing, but that doesn't sound like a factor in your case.

I've never met anyone on the "pro" side of pest control who ever said anything good about the paint additives. It's one of those easy and maybe too good to be true ideas. If you do go ahead with the paint, make sure it's not exterior latex, as I doubt that latex would work.

SuperSquirrel Member

The biggest hurdle I face is that the shed they're going after is in the middle of the wife's vegetable garden, so I have to try to avoid options that would run off, drift during application, etc. The deck, on the other hand, is fair game for pretty much anything. (Keeping the bees alive for pollination purposes would probably be appreciated, but I have to draw a line somewhere.)

The screening option is worth considering.

Shoot--maybe I'll just get a couple gallons of epoxy and paint everything with that. If they can get through that, they can have the shed.

SuperSquirrel Member

So here's a follow-up question on my previous treatment. I treated the bee holes during the summer with dust and sealed the holes with epoxy wood filler. When I was inspecting things today, I noticed small holes through the wood filler (maybe 2-3 millimeters, not the full round ½-inch hole). Do you think I wound up sealing eggs inside and that they were trying to chew their way out during the fall? Or is somebody trying to chew back into the existing holes?

marksr Forum Topic Moderator

Dusting the holes should have killed the bees, including any that hatched out. It isn't uncommon for the bees to return to the same wood to lay more eggs.

PAbugman Forum Topic Moderator

I suspect that parasitic wasps or the equivalent may have made the smaller holes, though I'm not sure. The newly hatched carpenter bees don't emerge until about September or so, depending where one lives. I can't imagine that a full-size carpenter bee would make a smaller hole to lay eggs. Though they do re-use holes from year to year, it sounds like you did everything correctly to prevent that.

SuperSquirrel Member

Well, a full-size bee certainly wasn't getting through those little holes. I'm not sure what size a juvenile carpenter bee is. I dusted and sealed up before September, so maybe it was the babies trying to get out. Guess I'll dust them and seal them again for good measure.

If I decide to go with a spray-on residual insecticide, would esfenvalerate be a reasonably safe one to use? I see mention that it's used on/around crops. I wouldn't be doing direct application to the vegetables, but there is a risk of wind drift or overspray. Either that, or a natural pyrethrin.

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