Log home owners, barn lovers, and folks with wood trim on their houses are probably aware of the damage carpenter bees can do. Yes, they are considered pollinators, but when repairing the damage to your structure costs more than replanting your coreopsis, it's time to draw the line.
Step 1: Materials
Note: I used power tools, but these traps can be made entirely with hand tools. But that's another Instructable.
Tools for cutting wood
Tools for drilling holes
One mason jar with rim
Screws, staples, and/or nails
One eye bolt with washer and nut
Various woodworking tools, like nail set (to tamp down errant staples), wire snips (to cut errant staples), hammer (to persuade errant staples), chisel (to remove errant wood chips)
You'll build a wooden box, taller than it is wide. You can use pine, cypress, cedar, plywood--your choice. I used 3/4" plywood. The size is entirely up to you, just as long as the bottom accommodates a mason jar rim. I angled the sides, but you don't have to. This is what I used:
Two 6" X 12" pieces (sides)
Two 7 1/4" X 12" pieces of wood (front and back)
One 7 1/4" X 6" piece of wood (bottom)
One 6" X 7 1/2" piece of wood (top)
Step 2: Build the Sides of the Box
Cut the pieces of wood to your specifications. I pre-drilled holes for the screws attaching front and back to the sides. Carpenter's glue will give more stability to the box. The lines you see were drawn at an angle as a guide simply to give the box a more graceful design. You can make your box as fancy or plain as you like. The secret to catching the carpenter bees comes a little later.
Step 3: Add the Bottom and the Jar Rim
Attach the bottom plate to the sides with carpenter's glue and your choice of fastener. Mark the center of the bottom by scribing diagonal lines from the opposite corners. Center the jar rim over the point where the lines intersect and draw around the inner circle. This will be the guide for your glue. Then drill a 1 1/2" hole at the intersection point. Run a bead of glue around the circle, and place the rim on the glue. Staple, screw, or nail the rim in place. Clean up the excess glue to prevent the jar from sticking.
Step 4: Attach the Eye Bolt
Turn the box over, propping it on two pieces of wood to protect the jar rim you just attached. Don't attach the top just yet. Mark the center of the top. Drill a hole big enough for the eye bolt and thread it through. Slip on the washer and tighten the nut with the ratchet wrench. Now apply a bead of carpenter's glue to the top edges of the box, and staple/screw/nail the top to the sides.
Step 5: Drill the Access Holes in the Sides
Using a 1/2" drill bit, drill access holes in the sides of the box. Angle the holes up, as the bees will find it harder to exit once they realize they're inside. It won't be a matter of flying in and flying back out. Drill a few holes; I drilled three on the front and sides. If there's a magic number, I don't know what it is. You just want enough, but not too many. Play it by ear. Keep the holes fairly clean, as the bees tend not to be ragged when they make their own, and you want to be as deceptive as they are destructive. It's a war, I'm telling you.
Step 6: Attach the Jar and Hang the Box
Screw the mason jar onto the rim. The jar can be unscrewed and emptied when it gets full. The theory behind all this is that the bees will enter the box, become disoriented when they can't easily crawl back out, and head toward the light, which is in the jar. Hang the box near your wooden structure and wait for it to work.
Step 7: Check Your Trap
Here's evidence that these things work. This shot is the day after this one was hung; you can see the carpenter bee's backside as he enters the trap. You might want to be on the lookout for recipes.