Identify Carpenter Bees and Get Rid of Them Safely

While carpenter bees and bumblebees are similar in size and appearance, there are some distinctive differences. Bumblebees have a black abdomen covered with yellow hairs or a stripe of yellow hairs, and a carpenter bee's abdomen is all black, hairless and shiny.

Bumblebees are ground dwellers that live in colonies. They will sting. Only female carpenter bees have stingers, and they rarely use them. Female carpenter bees are very laid back...not aggressive at all. The males are territorial, and may fly at you to defend their territory. They have no stinger, so it is all bluster. You can distinguish the gender of carpenter bees by their faces: males have white markings on their faces, and females' faces are black.

Carpenter bees are solitary insects. The females bore holes into wood siding or trees, making tunnels that can be 4 feet long and branching. These tunnels are called galleries. A gallery consists of a main corridor with small chambers off to each side. The female bores a chamber, deposits an egg, and packs the chamber with fresh pollen that will sustain the larvae. She seals off that chamber, and then creates additional chambers. More than one female may share a corridor.

A gallery entrance hole in wood siding is a perfectly round hole about 1/2 inch in diameter. It is often located near a window casing or high up near a soffit, but it is just as likely to be directly in the center of a siding board. You might notice yellow staining near the hole from the bee feces. Below the hole, you may notice fine sawdust called frass, which is deposited outside the hole as the bee hollows out her gallery. It takes her about 6 days to bore a one inch long section of tunnel.

The best way to get rid of carpenter bees is to simply fill the entrance hole with caulk and paint over it. Once the entrance is closed off, any larvae that develop into bees won't know what else to do, and they will die in the gallery. They do not bore holes further into the structure. A carpenter bee gallery in your walls is not usually considered structural damage.

One reason that you need to seal off a gallery as soon as you notice it is that the larvae attract woodpeckers, who will drill incessantly to get at them. Several species of woodpeckers relish the larvae, and they can do considerable damage in the process of getting to them. Woodpeckers begin at the gallery entrance hole and enlarge it until they can fit inside. Once the woodpeckers are inside the wall and have eaten the larvae, they sometimes use the space they have created for nesting...and the young woodpeckers may return to the site to drill their own nesting holes, instigating a much larger problem than a bee gallery.

A ladder and a tube of caulk can solve the problem.

See images at source link below.

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Sources:
Personal experience
http://ohioline.osu.edu/hyg-fact/2000/2074.html