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Carpenter Bee Biology


Carpenter bee on flower.Carpenter bees (sometimes called "wood bees" or "borer bees") resemble bumble bees. But the upper surface of a carpenter bee's abdomen is shiny black, whereas the bumble bee's is hairy with yellow markings.

Carpenter bees are primarily beneficial. Like all bees, they are efficient pollinators. They are also rather passive: The males will fly around dive-bombing anyone or anything in sight, but it's just macho. Male carpenter bees don't even have stingers The females do have stingers, but they almost never sting. They also do their part in combating childhood obesity because children seem to love chasing them around.

In fact, one would think their passive habits, industrious pollinating, and general good humor would endear humans to carpenter bees. So why do these beneficial, essentially harmless bees qualify as pests?

The answer is simple:

Carpenter Bees Drill Holes.

Carpenter bee hole. Photo courtesy of United Exterminating.Carpenter bees drill holes in wood. They drill perfectly round holes of about a half inch in diameter that look like they were drilled by a skilled carpenter (which, of course, is true in a sense).

Carpenter bee ejecta dripping from behind soffit. Photo courtesy of United Exterminating.In fact, it's hard to think of a piece of coniferous wood into which carpenter bees won't drill holes.

And just to add insult injury, carpenter bees seem to take special delight in drilling holes in impossible-to-reach areas, such as way up in the air along the edges of roofs, and behind clapboard siding, where they leave unsightly, waxy, difficult to remove stains known as ejecta. The more difficult a place is to get to, the more carpenter ants seem to enjoy drilling holes there.

Why do Carpenter Bees Drill Holes?

In all fairness to carpenter bees, they don't go around drilling holes just to annoy humans.

Female carpenter bees drill holes in which to lay their eggs. They lay multiple eggs in each gallery, separating them with a bit of sawdust and wax. The eggs are packed into the galleries a bit like tennis balls are packed into a can: Single-file along the length of the tunnels. They usually enter the wood perpendicular to the grain (often on its narrowest surface), and then turn ninety degrees amd drill their tunnels along the same direction as the grain.

Because the galleries inside the wood can extend as much as several feet along the grain past the visible hole on the outside of the wood, carpenter bees can cause serious damage to homes and other structures. Over time, the cost to repair this damage can amount to thousands of dollars, primarily because of the difficulty of gaining access to the high places and other protected areas in which carpenter ants drill their holes.

Next: Carpenter Bee Control