May/June 2011For Wildlife Watchers: Carpenter Bee by Rob Simbeck, photograph by Phillip Jones
There are actually hundreds of species of carpenter bees worldwide, but only two are common in South Carolina.
Humans have been good for a lot of species. We're not talking here about the ones we've domesticated, because for most of them, the arrangement has been a decidedly mixed blessing. But there are bird species - robins and mockingbirds for instance - that became a lot more numerous after we changed the North American landscape in ways that better suited them. Starlings have a whole new continent to inhabit thanks to us. Rats and mice are doing awfully well too, living large on our stockpiles and leftovers.
Then there are the insects drawn to our homes and outbuildings, such as paper and potter wasps, mud daubers and termites. This is a generally unwelcome group that people spend a good deal of time and energy trying to keep at bay.
But when it comes to at least one particular species of such visitors - the Eastern carpenter bee (Xylocopa virginica) - you won't find Whit Gibbons attempting to chase them away from his home.
"I say, 'Just enjoy them,' " says Gibbons, a senior professor of ecology at the University of Georgia's Savannah River Ecology Laboratory in Aiken and a terrific outdoor writer. "I have them on my back porch, and every spring I'm sitting there and little shavings are falling on what I'm reading or in my hair."
Now, the sight of insects that are dead ringers for bumblebees hanging around the deck or porch and, for good measure, chewing holes into eaves and ceilings might seem like a solid argument for an eradication effort, but Gibbons shoos it away.
"I don't tell anybody to try to control them, and I definitely wouldn't say to use pesticides on them. They won't be around long in any given year, and they've been drilling holes in our deck for at least ten years and the deck's still here. Meanwhile, they've given us a lot of enjoyment."
Eastern Carpenter Bee - Xylocopa virginica
Description: Looks very much like a bumblebee with a hairless abdomen.
Range and Habitat: New England to Florida, west to Texas and Nebraska. Common throughout South Carolina.
Reproduction: Females bore into wood and lay small numbers of eggs in sequential chambers. New adults emerge in August.
Viewing Tips: Look for small bore holes or small piles of sawdust anywhere unpainted or untreated lumber has been used, such as barns, outbuildings or decks.
It's part of a nature-friendly outlook that has made life a lot more interesting for Gibbons' kids and grandkids.
"Anything you find outside can be exciting," he says. "It's a continual learning experience. We know where every log and rock in the backyard is because we're always turning them over. I've got three grandsons who would rather get outside and look for animals than play video games."
Of course, it doesn't hurt that, thanks to his work, Gibbons can bring home the occasional baby alligator, but the point is a great one. More of us need to enjoy the nature that's closest to us, and to hear him tell it, the lowly carpenter bee can be as entertaining as just about anything.
"I'll get the kids and grandkids and say, 'Everyone put on a yellow hat or shirt,' and the bees will come after us. They respond to yellow. The males are so territorial they'll try to run off anything that comes near. Last year, we watched a particular male who hovered above a little bush every day, from daylight 'til dusk. You'd walk over and he'd come toward you."
That's not as risky as it might sound. Since stingers are modified ovipositors (an appendage used in the laying of eggs), male carpenter bees don't have them. Females do, but they're normally at work, too busy to bother with humans and very unlikely to deliver a sting unless actually handled.
Telling them apart is simple enough - males have a patch of white on their faces, while the females' faces are black. Distinguishing them from bumblebees starts with noting where they are. Bumblebees have underground nests and so are usually close to the ground. On the other hand, if there's a bee buzzing around the eaves or over your head, it's likely a carpenter bee. The main physical difference is that the abdomen of the bumblebee is fuzzy and yellow, while the carpenter bee's is glossy, black and hairless.
The holes that the female carpenter bees excavate are for nesting. Using their tough mandibles, they will chew nearly round holes approximately 3/8 of an inch in diameter into soft and preferably unpainted wood. The bees then turn right after an inch or two and chew a tunnel four to six inches in length at the rate of an inch every six days. The female creates brood cells along the length of the tunnel, forming a ball of pollen and regurgitated nectar, laying an egg on top and walling it off with a bit of chewed wood pulp. She does not eat the wood, most of which is excavated from the hole. Many people first notice they have carpenter bees around when mysterious piles of sawdust start appearing under beams made of untreated wood.
A carpenter bee egg is, proportionally, one of the largest in the insect world and has all the nourishment it needs to grow from grublike larva to pupa to adult in about seven weeks, by which time the female has died. The fully formed adults chew through the cell partitions and crawl out of the hole, over each other if necessary, emerging in late August. They gather and store pollen in the same corridor where they were hatched, living and overwintering there.
They emerge again in April or May, when the process begins anew. Once male and female mate, the female gathers nectar and excavates, while the male stations himself where he can decide whether to mate with or chase off whatever comes his way. Humans are just one more large intruder to be dealt with, and, as Gibbons points out, once you know they're harmless, it can be fun to have them get up close and personal.
Females will clean out old tunnels to reuse, and extend them several feet. They will also dig several corridors from the same vertical shaft. The excavation rarely causes enough damage to do serious harm to the structure, although woodpeckers will sometimes dig through the wood for grubs or adults.
There are actually hundreds of species of carpenter bees worldwide, but only two are common in South Carolina. Besides the Eastern carpenter bee that causes some homeowners fits, there is also a slightly smaller species, the Southern carpenter bee (Xylocopa micans). This species of carpenter bee only nests in trees, which is what Eastern carpenter bees do when there aren't any handy humans around to build appealing structures for them.
Both species of carpenter bees are excellent pollinators when it comes to open-faced flowers, so they're useful for many fruits, including pears, peaches, apples, plums and blackberries. On flowers with deep corollas, though, they will often use those strong mandibles to tear into the side of the corolla, swiping nectar without picking up or depositing pollen. Consequently, blueberry growers are no more fond of them than some homeowners.
Gibbons would like to see the number of fans - or at least interested observers - of the species increase, and given their utility as pollinators, their harmless nature and the fact that, in most cases, the actual damage their nesting causes is minimal, it's probably not a bad bandwagon to join.
