Carpenter Bee Males on Patrol

The territorial behavior of the male carpenter bee is both well-known and disconcerting.  Male carpenter bees dive at the heads and faces of homeowners and gardeners.  As an inquirer from Madison County recently put it, "The carpenter bees seem to know the moment we step outside.  They come straight up to you and buzz right in your face at a standstill - hovering and looking you straight in the eye.  They haven't harmed anyone but are a nuisance and scary nonetheless." It doesn't help that carpenter bees are big.  Body length is 19-23 mm, or slightly less than 1 inch.

Carpenter bees are solitary; each female works alone to burrow and provision a nest for her limited number of offspring.  Carpenter bees do not live in colonies or hives with a cast of thousands of worker bees to care for their colony and queen.

You may notice female carpenter bees coming and going from the ½-inch round holes bored into bare wood.  However, as described above, you are more likely to notice the males because they notice you!

Male carpenter bees hover around a nest site, flowers, or structures to defend their territory from other male bees.  Early in the season, they wait to mate with females as they emerge from old tunnels.  Later, they patrol the area to keep out perceived enemies.

Male carpenter bees are attracted to moving objects in their territory.  This could be people, pets, other insects, and birds.  Male carpenter bees act aggressively toward the alleged intruders, but it is all a bluff.  As with all male bees and wasps, male carpenter bees do not have a stinger and are harmless.  You can safely ignore the male bees or talk politely to your new best friend while appreciating the male carpenter bee's dedication and persistence to the limited and short role nature has given them.  Carpenter bee season is relatively short, which means the annoyance will be short-lived.  Carpenter bees usually appear in April, with peak activity in May to early June.

Female carpenter bees have a stinger and could sting, but they must be substantially threatened or handled to do so.  The females are busy as a bee with more important work to do than sting you.  They are docile, peaceful, and easily ignored. 

Are carpenter bees damaging?

The harm caused by carpenter bees is primarily aesthetic and aggravation.  It is conceivable that drilling into rafters, deck joists, and other structural lumber could weaken the wood, but it would take significant activity over an extended period.  Tunneling by female carpenter bees can be precluded by painting bare wood or spraying or dusting nest entrances.

For more details about carpenter bees, see our online article at https://hortnews.extension.iastate.edu/carpenter-bees