Carpenter bees can damage softwood of your home, but how do you know if the bee you see is a bumblebee, honey bee, or carpenter bee—and whether you should beware its sting, protect it as an endangered pollinating species, or eliminate it to prevent damage to your home?
Here is a comparison of the three bees and information on the damage caused by carpenter bees and what you can do to control them.
Carpenter Bee Facts
- At 1/2 to 1 inch long, most are similar in size to bumblebees, but some species can be as small as 1/4 inch long.
- The back end of this bee’s body (abdomen) is shiny black and mostly hairless, its body parts are more distinct than those of the bumblebee
- Some species are black, green, or purplish and may have various markings with minimal hairs
- They nest in the softwood of trees, homes, and other structures
- The male cannot sting, the female can but is unlikely to unless provoked
Bumble Bee Facts
- The bumblebee is 1/2 to 1 inch long; it is stockier than the carpenter bee.
- These bees are fuzzy, furry creatures with black and yellow bands across its body.
- They nest underground; travel from the nest to flowers to gather pollen.
Honey Bee Facts
- About 3/4 of an inch long
- Its head and legs are black; the center of its body (thorax) is furry and pale/yellowish; the back end of its body (abdomen) is shiny with alternating dark and orangish/yellowish bands.
- They nest in hives and are an endangered species.
Carpenter Bee Damage
To create their nests, carpenter bees bore round holes into softwood, which they then build out with expanding tunnels and galleries, or “brood chambers.” The carpenter bees prefer softwoods, such as cedar, redwood, and soft pines that are at least two inches thick to enable the building out of its nest.
Initial damage is slight, but as the bees build out their tunnels and chambers to raise successive generations, the structure of the wood can be damaged and weakened by the internal hollowing.
In the Carpenter Bee Nest
In the spring, the carpenter bees mate; build or expand their nests, and lay their eggs. To do so:
- Carpenter bees bore a round hole into softwood. For large carpenter bees, the hole is about 1/2 inch in diameter; it is much smaller for the small bees.
- Once the hole is about an inch deep, the bee then turns its boring to follow the grain of the wood and create a tunnel, initially about six to eight inches in length.
- Along the tunnel, the bees construct “brood chambers.” Into each chamber is placed a ball of food made of pollen and nectar. Then an egg is laid in the chamber and it is sealed shut.
- When the egg hatches, the larva feeds on the pollen/nectar mix and then emerges as an adult.
- This development can occur in about a month, or longer or shorter depending on geography and temperature. The bees can produce up to three generations during summer, with each female depositing six to eight eggs in each brood.
- The colony will overwinter in the wood, then mate and being again the next spring continuing to build out the tunnel and breeding chambers as the population grows.
Sings of Infestation
The following are signs of carpenter bee infestation in wood:
- Like carpenter ants, carpenter bees do not eat the wood (termites do eat wood). Rather, the bees excavate the tunnels, depositing the wood shavings outside the nest. This and defecation outside the tunnel openings provides evidence of carpenter bees.
- Male carpenter bees will flit around the opening of the nest, guarding it against other flying insects and predators. Thus if numerous bees are seen around your home’s eaves, doors, windowsills, decks, shingles, etc. where no hive is visible, they are likely carpenter bees.
- Bees will be seen early spring through late summer. During the winter, the bees will overwinter down in their nests within the wood; mate in spring, then emerge through summer to gather food. In warm, southern areas, you may see the bees year-round.
Source: Penn State University Entomology