How to Build Carpenter Bee Traps (That Look Nice)

Down here on the Gulf Coast, we have a lot of insect problems–mosquitoes, termites, fire ants, you name it.  Another common pest here is the carpenter bee, which is not at all aggressive, and a good pollinator to boot.  But carpenter bees also bore holes into exposed wood on decks, porches, and railings.  They are especially attracted to fresh wood, and they will even attack treated wood.  Over the course of a summer, they can significantly weaken a wooden structure.

Fortunately, carpenter bees are easily trapped due to their fatal weakness: they are unable to fly straight up, so if they fly into the top of a tall, narrow cylinder, they can’t get out again.  This weakness can be exploited by building a simple trap.

Carpenter Bee Trap 2019

I have seen many varieties of these traps around town.  Most are crude, homemade affairs, but a few are commercially produced.  They all work the same way.  This one is my own design.  It’s made of cedar, first because cedar is pretty weather-resistant, and also because carpenter bees are very fond of freshly-cut cedar, though mainly the white sapwood.

I began with a pile of 1/2″ thick cedar scraps and some mason jars.  I like the 16 oz. jelly jar in particular.  It’s tall and narrow, just the thing for trapping these bees.

Carpenter Bee Trap 2019

The box itself is about 4″ wide and 5″ tall overall (with a longer board on the back for mounting), but exact dimensions aren’t critical.  1 1/4″ long nails hold everything together.  Drill 1/16″ pilot holes for each nail to prevent splitting the wood.  (Each box will need 20 nails, so be sure you have enough.)

Here’s your cut-list:

  • 3″X3″X3/4″ pine, hardwood, or cedar (for the bottom)
  • 9″X3″X1/2″ cedar (for the sides)
  • 8″X4″X1/2″ cedar (for the front and top)
  • 8″X4″X1/2″ cedar (for the back)

If you can get only 3/4″ thick cedar, this is a great time to practice thicknessing your stock with a handplane.  Cedar is extremely easy to plane down quickly.

Carpenter Bee Trap 2019

I began with the bottom of the box, which is 3″ square and has a hole the size of the inside diameter of the jar’s ring cut into it.  (I drilled a 1/4″ pilot hole, then used a coping saw to cut the hole.)  I find that any 3/4″ thick pine or even a hardwood works great for the bottom, as it’s protected from the elements.  Because eight nails will pierce this bottom, it’s best to use a wood that doesn’t split as easily as cedar does, but you can use the cedar if that’s all you have.

Next, I cut out the sides of the box. You don’t really need to go to the trouble of cutting out a slanted roof, but since these boxes are going to be hanging on people’s porches, I want them to look nice.  And shedding water is not a bad thing for longevity, either.

To make the sides, I began with a board 9″ long and 3″ wide.  I measured 4″ in from one end on one edge, did the same from the other end along the other edge, and then drew a diagonal line across the board, connecting the two marks. Then I cut the line out with a handsaw.  No protractor, no measuring for angles.

After that, I measured out another piece for the front and top: 9″ long by 4″ wide.  Holding it up to the short end of one of my side pieces, I marked out the angle on the edge of what will be the front, just by eye.

After carrying the line across the face, I made the angled cut with a handsaw.  A bench hook is very helpful for making this cut.

The part that’s left over will be the roof, and it already has a perfect angle cut in order to sit up flush with the long, backing board.

I nailed the front onto the sides first, and then I nailed the sides to the bottom.  Make sure you nail only into the long grain of the bottom.  If you try to nail into the end-grain, too, you’ll split it.  After that, I nail on the back.

Before you put on the top, bore the three holes for the trap–one in the front and one in each side.  I use a 9/16″ auger bit, and since the cedar does split easily, I started with a 1/8″ pilot hole for the lead screw.  Bore the holes nearer the top of the box than the bottom.

Now nail the roof in place and drill some pilot holes in the top of the back board for mounting.  Finally, get ready to attach the ring to the bottom.

Use a larger nail to punch four pilot holes around the ring, and then nail the ring to the bottom.  (Discard the lid that came with the jar.)  You may need to use a nail set to drive the nails all the way in.

It also helps to drive them in at an angle instead of straight up and down.

Carpenter Bee Trap 2019

Now screw the jar into the ring, and the trap is complete.  This took me about half an hour from start to finish.

The effectiveness of the trap does depend on good placement.  Watch the bees for a while, and place the trap where they tend to linger.  It will probably be up near the ceiling and/or under the eaves.  Soon the jar should be full of dead bees, and you’ll be able to empty it out at the end of the season.

Carpenter Bee Trap 2019

I have two of these traps on my porch, one on each end, and while one of my traps was full of dead bees in a few weeks, the other one hadn’t caught a single bee.  That’s real estate for you–location, location, location.

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3 Responses to How to Build Carpenter Bee Traps (That Look Nice)

  1. Steve D says:

    That is awesome. I have carpenter bees infesting some pine doors and I just covered my house with new cedar shingles. Thanks for the timely post.

    Even if they were ugly, I’d build them.

  2. fedster9 says:

    I dunno — I do get that insect infestations are a massive pita and can be a real and serious problem, but I am extremely lukewarm about removing pollinators. Like the passenger pigeon, it looks like there is an endless supply, but that is not the case in any way, shape, or form. I was wondering whether it would be possible to have some wooden structure that is sacrificial, so that bees that use that get a pass, and bees boring in other parts of the structure get zapped (personally and individually).

    • Thanks for sharing your thoughts. With these traps, theoretically you could remove the jar with the bee still alive and relocate the insect elsewhere. It would be a lot of work, especially since infestations often involve dozens of bees. Beyond that, I think that it’s far better to use local traps like this instead of broad-spectrum chemicals to deal with insect problems. I know that there are a lot of legitimate concerns about the decline of pollinating insects in the USA these days, but that doesn’t mean that such insects can’t overpopulate a local area and destroy structures. These traps don’t kill every single insect; they just keep the population in check and minimize damage.

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