How to Make a Carpenter Bee Trap

Spotted hovering along deck rails or under house eaves, an all too familiar pest returns in the spring. Often mistaken for bumble bees, carpenter bees can be distinguished by their smooth and shiny-black abdomens. Although the males have no stingers, they aggressively patrol the area around their nests as the females busily prepare their favorite nesting spots. It’s those nests that make the carpenter bee a true pest for homeowners.

The handiwork of these illustrious borers becomes more and more apparent through late spring when you can find holes in houses, decks, patio furniture or chicken coops. Carpenter bees seek out bare wood or even treated wood that has been softened though weathering. The preferred nesting location for the carpenter bee is deep inside that exposed wood. The female bees chew holes roughly half an inch wide into the wood and produce tunnels three to four inches deep under the surface in which to lay their eggs.

The bees create cells within those tunnels, each containing eggs and a packet of gathered pollen on which hatching bees can feed. Offspring will stay in these cells until next spring when they emerge, ready to repeat the cycle.

Left to their own devices, populations will rise and the unsightly holes left in siding, decks or other wood structures will multiply exponentially as new bees emerge. If your garage is starting to resemble Swiss cheese, steps can be taken to put an end to a troublesome carpenter bee occupation.

A fresh coat of paint on exterior wood structures is a good deterrent from new construction. Barring that, repeated treatment of exposed wood using an appropriate insecticide will help reduce an existing adult population and discourage further damage.

Existing nesting holes must be destroyed and sealed. Using a piece of flexible wire, thread the wire down the holes — piercing the egg cells of the existing nests — and then spray an insecticide into the holes. Once spraying is complete, plug the holes to prevent further occupation. Although male carpenter bees cannot sting, females may defend if provoked and care should be taken when approaching active nests.

There are plenty of DIY carpenter bee trap designs found online. Some are better than others, but most are based on the same principles. Appealing to carpenter bees, half inch holes are drilled into a wood box at an upward angle that prevents direct sunlight from shining in. A clear, tapered bottle is attached to a hole in the bottom of the box. Once the carpenter bees have entered the box, the hole at the bottom of the box is the obvious exit. Once trapped, the tapered shape of the bottle prevents them from escaping — pretty darn clever and every bee trapped is one less hole chewed into the gazebo next year.

See these step-by-step instructions on building a simple carpenter bee trap.

1. Cut Wood Pieces for Carpenter Bee Trap

Find an untreated 3/4-inch-thick cedar or soft pine plank that's 4-1/2 inches wide and at least 5 feet long (scrap wood is just fine for this project). Other materials required include a 20-ounce clear plastic soda bottle (with cap) and nails or screws for trap assembly. Use a miter or hand saw to cut the following lengths: four 8-inch lengths (sides), two 7-inch lengths (roof) and one 6-inch length (bottom).

2. Assemble Sides of Trap

Assemble the sides using nails or screws to attach along edges.

3. Attach Roof Panels

Lay the two roof panels side by side on top. Center and attach with nails or screws.

4. Drill Entry Holes

Drill 1/2-inch holes into three sides of the trap roughly 1-1/2 inch from the roof. Holes should be angled upward at least 45 degrees to prevent sunlight from shining in. These are the holes through which the bees enter the trap.

5. Drill Out Bottle Cap

Drill out the top of the bottle cap using a 1/2-inch or 9/16-inch drill bit, taking care to avoid damaging threads.

6. Drill Hole in Bottom Panel

In the bottom panel of the trap (not yet attached), drill a hole the diameter of the bottle cap (usually 1-1/8 inch).

7. Fit Bottle Cap Into Bottom Panel

Gently tap the bottle cap into the hole in the bottom panel of the trap. It should fit securely without adhesive, but glue may be used if a snug fit is not achieved.

8. Attach Bottom Panel and Hang Trap

Attach bottom panel to trap using nails or screws. Add a hook or string to the top for hanging purposes and thread bottle on to trap bottom. Hang securely along fascia in an area where carpenter bees have been seen previously. When trap is full, the bottle may be discarded and replaced.