Why Do Carpenter Bees Chew Wood? Some Facts About Their Nests

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Carpenter bees are named as such because of their penchant for woodworking. But why do carpenter bees chew wood? Do they need the wood to nourish themselves? Or is the wood just in the way of nest making?

why do carpenter bees chew wood

Carpenter bees have special woodworking skills that are unique to them. CC Image courtesy of Docteur Cosmos on Wikipedia

Carpenter bees don’t eat wood

They’re not like termites, so they don’t eat wood. They bore into trees and wood to make their nests. So they don’t need the wood’s fibers for any special reason other than to create homes from themselves.

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Carpenter bees, like the rest of the bees, eat honey. However, they don’t make it like honey bees do. A female carpenter bee collects pollen and nectar and brings them back to her wooden burrow. The pollen is carried using a bee basket while the nectar is temporarily “placed” inside the bee’s stomach. When the female bee gets home, she regurgitates the nectar and spits it into the pollen. She then uses her legs and mandibles to form a ball of wet pollen food for her brood to be encased in. That nectar she spitted is somewhat similar to honey.

They chew wood to build their nest

Female carpenter bees excavate wood tunnels to shelter themselves away from the elements and to make a place of their young to grow.

They begin the process by drilling into the wood of their choice. Using their mandibles, they form a hole that has enough room for their body to squeeze into. This entrance hole is usually 1/2 inch in diameter, and in the future, it’s going to be connected to a bunch of other tunnels.

Carpenter bees typically drill against the grain of the wood. But according to Penn State’s College of Agricultural Sciences, when their tunnel is about 1 to 2 inches deep, they turn at a right angle that’s relative to the initial hole and drill following the wood’s grain. What results is a small set of chambers with varying lengths and sizes, all connected to one exit-entrance. And over time, the carpenter bees will also expand their nests and build new tunnels alongside the old ones.

The carpenter bee’s woodworking skills have been loathed by many homeowners for as long as we can remember. That’s because their tunnels can become so extensive that the wood they’re built into will eventually break down in the coming years. It will harbor moisture, mold, stain and other parasites as a result of being hollow inside.

Here’s a video from the North Carolina: Museum of Natural Sciences for more information on why carpenter bees chew through wood.

So where do carpenter bees usually live?

Carpenter bee

Generally, carpenter bees attack dry unpainted wood. But they can also live inside various trees. To help you inspect your home for these bees, here’s a list of the most common places that these bees can drill into.

  • doors
  • windowsills or trims
  • walls
  • beams
  • decks or porches
  • railings
  • sidings
  • roof eaves
  • fences
  • thick wooden shakes
  • telephone poles and other untreated poles
  • and sometimes even outdoor furniture​

Carpenter bees prefer to burrow into:

  • cypress
  • fir
  • pine
  • cedar
  • some redwood​

So why do carpenter bees chew wood again? Of course, it’s to build their nests. Remember that unlike termites, carpenter bees won’t devastate your house. They will, however, excavate more tunnels if they grow in numbers. And that will still cost you a lot.

To keep them away, you should only build with treated wood. You should also try to paint them. For more tips, here’s a detailed guide on how you can keep these bees away from a house mostly made out of wood.

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