Bunkin’ With the Bees

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Like many other folks working from home right now, trying to set up a workable “home office” with enough peace and quiet has been a challenge. Relocating from room to room in search of solitude I thought I found my last refuge – the screened-in back porch. Gentle breezes, and peace at last – or so I thought. Evidently carpenter bees think my screen porch is the perfect place too.

Carpenter bees are large, black and yellow bees frequently seen in spring hovering around the eaves of a house or the underside of a deck or porch rail. They are often

Carpenter Bees

mistaken for bumble bees, but differ in that they have a black shiny tail section. The carpenter bee is so-called because of its habit of excavating tunnels in wood with its strong jaws. The round half-inch diameter entrance holes are usually found on the underside of a board. A tell-tale trace of coarse sawdust is often found on the surface beneath the hole. Wooden decks, overhangs, and other exposed wood on houses are prime targets. Painted and treated woods are less preferred, but they are by no means immune to attack.

Unpainted or stained cedar, cypress, and redwood shingles and siding are also attacked despite their pest-resistant reputations. Carpenter bees, like their distant relatives, the carpenter ants, differ from termites in that they do not eat wood as food. They simply excavate tunnels for nesting sites. While the nature lover in me thinks they are pretty awesome pollinators, the homeowner is not happy at all to have destructive squatters.

Unlike bumble bees and honey bees, carpenter bees are “solitary bees”, i.e., they do not form colonies with worker bees to maintain a nest or care for offspring. The mated female bees feed on plant nectar and then begin constructing new tunnels in a few weeks, so they are getting into my flowers and pollinating them as they hunt nectar.

The insecticide route is an option for folks who find they cannot abide these bees. Identifying the evidence of carpenter bee activity is not hard, but actually applying effective chemical treatment is not as easy as you may think. The entrance holes start upward (or inward) for about one-half inch or more, then turn horizontally and follow the wood grain. The galleries typically run 6 to 7 inches, but may exceed one foot. Occasionally, several bees use the same entrance hole, but they have individual galleries branching off of the main tunnel. If the same entrance hole is used for several years, tunnels may extend several feet in the wood.

Passive traps are alternative management tools that have been proposed to address carpenter bees problems. These traps, either for purchase or Do-It-Yourself, are said to exploit the behavior of carpenter bees that explore round openings in wood. Based on the design, insects enter through an opening in a block of wood, but get trapped in a double bottle funnel or catch jar. In this way, traps are a proactive method of addressing carpenter bees before they cause damage.

Inside her gallery, the female bee collects pollen which she mixes with nectar to form a ball that will serve as food for her offspring. She deposits an egg near this pollen ball and then seals off this section of tunnel with a partition made of chewed wood. She constructs additional cells in this manner until the tunnel is completely filled, usually with 6 to 7 cells (depending on length of the tunnel). These adult bees die in a matter of weeks. The eggs hatch in a few days and the offspring complete their development in about 5 to 7 weeks. The new generation of adult bees begin to emerge in later summer. Although the bees remain active, feeding on pollen in the general area, they do not construct new tunnels, but may be seen cleaning out old tunnels which they will use as overwintering sites when the weather turns cold.

As a plant geek and beekeeper, I’m opting for building the trap using this design, based on test results conducted at Cornell University.

Trap construction directions

Check out the bee trap how-to video!

Carpenter Bee Trap

Minda Daughtry is the Horticulture Agent for North Carolina Cooperative Extension in Lee County.