The Beekeeper’s Companion Since 1861
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The Curious Beekeeper

America’s Most Wanted is a Master Carpenter

- April 1, 2022 - Rusty Burlew - (excerpt)

Eastern Carpenter Bee

Emblazoned t-shirts, coffee mugs, and license plate frames exhort us to “Save the Bees!” Scores of organizations single out species of concern, such as honey bees or native bees, while others promote any old bee. According to a representative of the Xerces Society, bee training seminars that once attracted a half-dozen participants now attract hundreds.

But regardless of all the attention, one species in North America is slipping through the cracks, failing to make the cut amidst all the bee love. Many people who are otherwise bee-centric are perfectly content to slaughter this one particular species. I’m not thinking about non-native woolcarders or the introduced Asian shaggy digger bees. No. I’m referring to our own native eastern carpenter bee, Xylocopa virginica.

The eastern carpenter bee is a pollination wunderkind. It is a large hulking species adept at sonication, that essential but rare trait that allows a bee to lock onto a plant and quiver, shake, and shimmy until the pollen explodes from its hidden chamber. Other sonicators live in the wild for sure, including bumble bees and some leafcutters. But with our love of the Solanum — such as tomatoes, potatoes, and eggplants — and the Vaccinium, including blueberries and cranberries, you can’t have too many sonicators.

So what about this charismatic bee crosses the line? Why does her photo grace the walls of the post office? The answer centers on territoriality. Not hers, but ours. We don’t like things living in — or remodeling — our homes uninvited. “Mine!” we declare. “My house, my barn, my lawn furniture.” So we mark her for destruction, no matter what she could have done for our environment and grocery shelves.

An abode of redwood

When I was a kid, my parents bought a circular redwood picnic table made of thick lumber, lovingly constructed, and quite expensive. Soon after delivery to our patio, a large carpenter bee showed up unannounced. She hovered at the edge of the table and drilled straight into the wood with a high-pitched whine reminiscent of a dental office.

After my mom shooed her away, I stuck my finger in the hole. It reminded me of a tiny test tube, rounded at the bottom and smooth as glass — the coolest thing ever. I was enchanted, but my mom was livid. She marched toward the house, promising to be right back.

Where humans go, carpenters follow

Like cats, carpenter bees prefer to live near humans who surround themselves with useful objects. Like us, carpenters admire fence posts, windowsills, fascia boards, railings, decks, shakes, and garden gates, and if the wood is unpainted, so much the better.

That carpenter bees actually practice carpentry on those items leads to trouble. They adore new wood, especially softwoods such as pine, fir, cedar, and redwood. They search for lumber thick enough and soft enough to excavate a nest in their own trademark fashion, but if no milled lumber is available, cordwood or a dead tree will do.

A carpenter’s tunnel

The build goes like this. The female drills straight into a piece of wood perpendicular to the grain. At about one body length — or roughly half an inch — she makes a hard ninety-degree turn. From there, she follows the grain, clearing a spacious cavity large enough to lay her eggs and accommodate the next generation. These hollow caverns are called galleries.

The female shoves most of the shavings and sawdust outside. Sometimes you can see it drifting in a cloud or discover a fresh pile on the ground beneath an excavation. They reserve the rest of the shavings for partitions that will separate individual egg chambers. Like many bees, the female begins a family at the far end of a tunnel by fashioning a nectar-laced pollen ball and laying an egg on top of it. Then she builds a particle-and-resin partition before beginning the next brood cell.

A carpenter bee egg is enormous, one of the world’s largest insect eggs. While a honey bee egg measures about 1.5 mm long, a carpenter bee egg reaches 15 mm. But its rarity tempers the egg’s size: An average female carpenter lays about a half-dozen in her entire life.

A maze of tunnels

One tunnel in a piece of wood is annoying, yet not too damaging. But carpenter bees possess a genetic trait known as philopatry, meaning subsequent generations nest close to home if they can. Some will even return to their natal nest. Soon-to-be moms are social enough to share a front door with other moms, each excavating a private nest from the shared vestibule.

After a few years, wood that once hosted a single tunnel becomes laced with compound galleries, often running parallel to each other along the grain. The multiple excavations can cause structural problems that may remain hidden. What appears as solid timber from the outside can be a house of cards — a catacomb beneath a thin veneer of wood, ready to collapse at any moment.

Other annoying habits

Drilling into homes and possessions is the major complaint against carpenter bees, but not the only one. Bees going in and out of their homes like to defecate at the nest entrance, leaving golden-brown streaks that stain the wood below. Apparently, even people who can overlook the hole are less philosophical about the fecal deposits, describing them as disturbing or low class. As anyone with honey bees knows, a quick squirt with the garden hose only makes the spots glisten.

In addition, some gardeners complain about the damage carpenters inflict on their flowers. Known for nectar robbing, they never hesitate to bite into the base of a corolla to access the nectar within. Although carpenters are excellent pollinators, they are big, unable to fit into skinny flowers with long tubular petals. When a svelte flower promises a good meal, the carpenters bite their way in, leaving slits in the petals that turn brown along the edges.

Because the slits are inviting, bees not adept at petal-biting will also visit the nectar cafe, enjoying a meal ready to eat. Honey bees, especially, like to take advantage of pre-split feed bags.

And finally, some homeowners complain that carpenter bees attract woodpeckers. The woodpeckers can detect brood under the thin veneer of wood that covers the galleries. With little effort, the birds can poke into the wood, casting splitters and carving holes.

The intimidating males

Known for intimidation, trespassing, and harassment, the males also have a PR problem, if not a mugshot in the post office. Because of their aggressive behavior, many folks shy away from them, fearing an attack. A sturdy bee hovering in midair while making prolonged eye contact can be offputting, but that is exactly what they do. Although they are all bluster and pomp, with no weapons beyond beady eyes, people give them a wide berth, preferring to exterminate rather than ignore them.

Like other male bees, male carpenters have no stinger, but they gather in agitated groups and make aggressive passes at all who enter their territory. They are unimpressed with your size or your ownership rights, so they try to make you leave.

How to identify a carpenter bee

The eastern carpenter covers a lot of territory in North America, ranging from southern Canada into Southern Florida, and from the Atlantic coast as far west as New Mexico. Because of their enormous size, they get confused with bumble bees. But eastern carpenter bees have a shiny, nearly hairless abdomen compared to ….