Bees are important insects because they serve as global pollinators, but some bees can also cause damage in your home and may need to be exterminated. Carpenter bees, as their name suggests, can damage the wood in and around your home. They make long, deep burrows into wooden material, where they live and reproduce.
Unlike their honey-making cousins, many people don’t know what carpenter bees are, how to spot them, or how to treat for them once you know they are there. As always, we are here to help, telling you everything you need to know about these buzzy little wood-chewers.
How to Spot a Carpenter Bee
Not everybody has heard of carpenter bees, but you’ve almost certainly seen them. They typically around 3/4″ long and not especially rare in the United States. Unless you know a lot about bees, it can be hard to tell the difference between a honey bee, a bumblebee, and a carpenter bee.
Honey Bees vs Carpenter Bees
Honey bees are easy to distinguish from either of the other two kinds because they are much smaller and have more yellow and orange coloration without much black. They live in very large colonies and produce edible honey.
Bumble Bees versus Carpenter Bees
Bumblebees and carpenter bees look similar to the untrained eye. They are both much larger than honey bees and have more black on their bodies. However, there are a few characteristics you can use to tell them apart.
Fur and sheen: Bumblebees have furry abdomens, while carpenter bees have much less hair. Instead, their abdomen will have a blue-black, green, or even purple metallic sheen.
Color: Bumblebees will have at least some yellow on their abdomen (the long, rear-section of the bee). Carpenter bees are usually all black.
Aggression: Carpenter bees can be aggressive and territorial, which makes sense because they live a solitary lifestyle. The stingless male tends to be more aggressive than females. Bumblebees are much more timid. They are mostly blind, so they only sting in true self-defense.
Where you find the bee: Carpenter bees are also known as solitary bees. They burrow into wood and don’t really interact with other bees, though many individual bees often nest in the same piece of wood. Bumblebees live in colonies in the ground. These features don’t always help if you’ve found a single bee, but they can be useful in the field or around your home.
What Damage do Carpenter Bees Cause?
For a single bee, the damage might be minimal. They start by digging a hole straight into the wood, about 1/2 inch in diameter. This hole usually goes about an inch deep, then makes a right angle and runs in a straight line with the grain of the wood.
These holes look very clean, as if a human took a drill and made it themselves!
A single female carpenter bee can excavate about 1 inch every 6 days and may only need 4-6 inches, so they aren’t going to take down a structure overnight.
However, this damage adds up as bees tend to return to the same wood each year. Once an individual bee has success burrowing into a piece of wood, it doesn’t take long for other bees to join in on the good real estate. Over time, you can get tunnels up to 10 feet long! It’s just a lot slower than wood-eating insects like termites.
Now I just told you that carpenter bees make tunnels fairly slowly and make a clean entrance to their tunnels. You might be thinking “but I’ve seen carpenter bee damage that looks much worse than that”!
You’d be half right!
Once a female bee clears out her gallery, she lays her eggs which become larvae. These larvae are quite loud and frequently attract woodpeckers.
Woodpeckers will go right along the tunnels that the bee made and peck into the wood in order to snatch out the grubs. The resulting damage typically looks something like this –
While carpenter bees themselves don’t make these long, oval holes in your wood, they are responsible for attracting the woodpeckers that do.
3 Steps to Getting Rid of Carpenter Bees
1) Apply a Pesticide
The first order of business is exterminating the bees living in the wood. Many people use a pesticide dust for this which can work fine, but I prefer an expanding foam such as Fuse Foam.
Fuse Foam is perfect for treating carpenter bee tunnels. Simply apply inside the entrance of the tunnel and it will expand deep inside, effectively killing the bees rapidly.
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Fuse Foam comes in a very easy to use canister. You just point the nozzle into your tunnel entrance and pull the trigger. The can will eject foam deep into the tunnels and galleries where other pesticides can never reach. This will kill the bees much faster than alternatives. Don’t forget to shake the can before operating!
After applying the pesticide, I’d recommend waiting at least 48 hours before continuing to the next step. You’re going to want all the carpenter bees using the tunnels to come into contact with the pesticide, otherwise they won’t die and may just start new holes elsewhere.
2) Replace the Wood or Fill the Holes
Depending on the extent of the damage, you can choose between replacing the wood or sealing the holes with wood putty. It will almost always be easier to just use wood putty, but this is completely up to you.
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You want to be sure to cover any signs that carpenter bees used to nest here so other carpenter bees don’t get any ideas!
Note: when buying a wood putty or wood filler, make sure you get something that’s rated for exterior use. Some products won’t be able to withstand outdoor conditions.
3) Varnish or Paint Your Wood
Carpenter bees do not like painted and varnished wood as much as they like raw wood. Most of the time they’ll just keep moving along and look for a better home. Treat as many of your wooden surfaces as you can with paint and varnish.
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If you’ve never treated with varnish before, it’s about as easy as just painting on the varnish. Just make sure to use a new varnish versus one that’s been sitting in a garage for many years. Additionally, make sure to get a good, strong brush that can hold up to a material as harsh as varnish.
Most wood putties sold today are paintable, but be sure to check your label if it’s something you’ll be doing. Some putties don’t hold paint very well and may look poorly when finished.
How Can I Repel Carpenter Bees?
Carpenter bees require softer woods to burrow into, so they prefer raw, untreated redwood, cedar, poplar, cypress, and pine. If you have surfaces made of these woods, make sure to paint or pressure-treat them.
Keep in mind that softwoods are usually used for doors, window frames, porches, and furniture. It’s unlikely you’ll have carpenter bees living in your walls, ceilings, or floors. These are usually made of harder woods.
If you know you get carpenter bees regularly, you may want to spray a residual pesticide on your wood surfaces yearly. This step should not be necessary for one-time infestations, however.
A product like Bifenthrin would be a great annual spray treatment.
The good news is that carpenter bees work slowly. So if you catch them in time, it’s not too difficult to get a handle on the situation. Most major issues with carpenter bees occur when the problem goes unnoticed for many years.
Carpenter Bees FAQ’s
Like all large bees, female carpenter bees can sting. The males tend to be more aggressive and spend more time outside of the galleries, but they cannot sting. Females usually only sting if they feel their nest is threatened. So if you’re in doubt and a bee is flying at you fast, assume it can sting just to be safe.
Yes. The bees don’t really eat the wood. They get their nutrition from flowers just like other bees. In fact, there are some plants that can only be pollinated by carpenter bees because of the unique, short shape of their mouthparts.
Carpenter bees are not the strongest burrowers, so they require softwood to make their nests. Some of the woods that carpenter bees like to dig in are redwood, cedar, cypress, poplar, and pine, which are also common materials for doors, window frames, furniture, and porches.
Carpenter bees are fairly large, so they require rather large holes. They are usually around a half-inch in diameter, and their hole entrances can be recognized by the fact that they tend to go straight in about an inch before turning and running parallel to the wood grain again.
Males will frequently be found in and around the entrance to the tunnel, guarding it.
You can also keep your eyes open for small piles of sawdust and pollen around the entrances to the tunnels. Since carpenter bees dig through the wood rather than digesting it, they produce sawdust (unlike termites).
It’s unlikely to work, but you can try. The bees live in their tunnels, even in the wintertime. If you manage to catch them while they are out pollinating, you could quickly seal the hole and varnish the surface to see if they go elsewhere.
However, you would be killing any eggs the bee has laid in the hole (if female), and the bee may struggle to find another place to nest and die anyway. Worse still, the bee could just turn around and nest somewhere else on your property.
The best way to keep carpenter bees away without harming their population is prevention. Treat your wood surfaces and fix any small nests immediately to prevent other bees from nesting there as well.