Carpenter Bees and The Damages They Can Cause

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Carpenter bees are often categorized into two genera- Xylocopa (large carpenter bees) and Ceratina (small carpenter bees). These two genera do not have the same size, and this is probably the most obvious characteristic used in differentiating between both of them. While Xylocopa is around 12-25 mm long, Ceratina is less than 8 mm long.

Carpenter bees derive their name from the fact that they build their nest in woods. Large carpenter bees have the same size and appearance as bumblebees. However, the top of their abdomen has a somewhat glossy look as they lack the visible hair that is found on those of bumblebees. Unlike Ceratina, Xylocopa infestation is easier to detect because they make their presence known through property damage.

The insects can be black, purplish blue, metallic blue or greenish black. Yellowish hairs can be found on the legs, abdomen, and thorax of both the male and female carpenter bee, but these hairs aren’t as many as they are on bumble bees. The majority of small carpenter bees feature yellow markings on the face and body, scant body hairs and have a somewhat metallic appearance.

Both Xylocopa and Ceratina go through a complete metamorphosis from egg, larva, pupa and the adult stage. Carpenter bees are solitary insects and therefore do not organize into colonies. Although male carpenter bees do look menacing as they buzz around, trying to intimidate insects, predators and even humans who trespass into their territory, they are unable to sting. The females, on the other hand, can sting if they are provoked.

The Behavior, Diet, and Habit of Large Carpenter Bees

Carpenter bees feed on plant pollen and nectar. Although they do not eat wood, they can excavate dry, weathered and unpainted wooden objects such as railings, doors, windowsills, untreated poles, roof eaves, wooden lawn furniture, decks, and fences. They prefer oak, pine, fir, Cypress, redwood or any other soft wood.

Occasionally, large carpenter bees bore into painted wood, if the paint covering is old and worn out. Since gallery construction takes a lot of time and energy, the female carpenter bee prefers to lodge in existing nests instead of building new ones. Overtime, the refurbished tunnels may increase by several feet. The female carpenter bee single-handedly builds the nest by drilling out a nickel-sized hole in flat wood surfaces.

Slightly less than 1/2-inch wide, the hole is usually the diameter of the female’s body and appears much like an opening created by a carpenter with a 1/2-inch drill. The carpenter bee digs the hole a couple of inches in and then takes a right-angle turn following the grain of the wood to create a tunnel that runs about 4-8 inches in length.

Next, the bee partitions off brood chambers into linear rows and places a food ball in each chamber. The carpenter bee dies after laying the eggs and using chewed wood pulp to block the chamber. When the eggs hatch and become larvae, they feed on the food ball which is made of pollen and nectar until they pupate.

The behavior, Diet, and Habit of Small Carpenter Bee

Small carpenter bees excavate stems and twigs to construct their nests. The adult female Ceratina overwinters in either completely or partially excavated stems, and like the Xylocopa, they excavate and create a brood nest in the spring.

They also provide food balls in each brood cell for their young. Amazingly, a few species of Ceratina can reproduce without males. This trait is known as pathogenicity.

Life Cycle

The life stages of the carpenter bee include egg, larva (grub), pupa (cocoon) and adult states. Depending on geography and temperature, it takes about seven weeks for the egg to hatch and reach adulthood. New adults do not leave their galleries until April or May. They mate, eat up pollen and nectar, then go back to their gallery to overwinter to emerge the following spring.


Unlike the social bees and wasps, female carpenter bees deposit only about 6-10 eggs in each brood and die after that. The males die a short while after mating.

Signs of A Carpenter Bee Infestation

When excavating tunnels, carpenter bees deposit the wood shavings outside the nest. The presence of sawdust on the ground right under the tunnel opening, bee excrement and a yellowish combination of pollen near the entrance hole provide evidence of carpenter bees.

While it is true that Carpenter bees are important pollinators, they are also a nuisance. Here are some of the damages they can cause.

1) Structural Damage: The female carpenter bees usually bore round holes into soft wood to create their nest. The initial damage may seem small, but if the bees continuously tunnel in the same structure, the cumulative damage can be significant. The gallery and excavations of the carpenter bee weaken and damages the structure of the wood after some time. Ignoring this damage could put the structure at risk of collapsing.

2) Stains: Besides being unsightly, the feces of the carpenter bee can stain wood. This can reduce the value of your home and make it unpleasant to stay in.

3) Water Damage: The wood rots faster when moisture enters into the tunnels. If the tunnels are situated in your home’s siding, the damage would be even more severe.

4) Woodpeckers: Immature carpenter bees attract insect eating birds. Woodpeckers riddle the wood with holes looking for larvae to eat. Their damage could affect the structural integrity of the building in so many ways.

If you find numerous bees hovering around your doors, decks, Windowsills, shingles and other areas where no hive is visible you may have a carpenter bee infestation. Detecting carpenter bees on time helps you to eliminate them before they cause extensive damage to your property. 

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