Carpenter Bees and Your Deck: A Comprehensive Guide

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A carpenter bee entering its burrow.
A carpenter bee entering its burrow. You can identify carpenter bees by their hard exoskeletons and their affinity for wood.

Few things haunt the nightmares of deck enthusiasts like swarms of carpenter bees closing in on their beloved wood decks. The money and time homeowners put into caring for wooden decks makes them a significant investment that needs protection, especially since a deck in disrepair can affect your outdoor enjoyment and your home’s value. Whether you are researching deck maintenance in preparation for having a wood deck installed or trying to stop a carpenter bee infestation, knowing what attracts carpenter bees, how to spot them, and how to stop them may save your deck’s life.

What kinds of wood decking do carpenter bees like?

It’s a common misconception that carpenter bees feed on wood. Carpenter bees chew through wood, but they do not eat it. Of course, this is probably little consolation if you suspect carpenter bees are currently ravaging your deck.

Certain types of wood are more attractive to carpenter bees. The bees prefer unpainted, unfinished woods, so if you want to ward off carpenter bees, consider finishing your wood deck with varnish or paint before an infestation can take hold. Softer woods like pine—which also happens to be one of the most common wood decking materials—are easier for carpenter bees to tunnel through and therefore more likely to attract these pests. If you opt for an unpainted pine deck over a harder material like mahogany, you might especially benefit from finishing or painting it to keep the bugs out.

What decking materials are carpenter bee-resistant?

Pressure-treated wood decking

Pressure-treated wood is subjected to protective chemicals that make it more durable and also more resistant to insects. The pressure-treating process makes wood denser, which may be a turn-off to carpenter bees. However, pressure-treated wood isn’t a complete deterrent. Pressure-treated wood can soften with age, making it vulnerable to carpenter bees’ nefarious attentions.

Composite decking

If you are still in the stages of planning your deck and have concerns about carpenter bees or other insects that might make a home or a meal of your deck, alternative decking materials may be for you. PVC and composite are a bug-resistant (and pretty-much-everything-else-resistant) decking material that carpenter bees simply can’t tunnel into. Since composite decking is finished during the manufacturing process, composite deck owners can skip this particular maintenance step–in addition to most other maintenance. Synthetic decking materials don’t warrant repainting or resealing and simply need to be rinsed off with a garden hose as infrequently as every year.

How do I know if I have carpenter bees?

A honey bee pollinating a flower.
A honey bee polinating a flower. Note the fur that differentiates these bees from carpenter bees.

The telltale signs of carpenter bees are probably the things that got your attention in the first place: holes in your deck, piles of a sawdust-like material, and most obviously, hordes of bees swarming around your deck or your home. The holes, usually about half an inch in diameter, are the entrances to the bees’ tunnels, and they may be marked by yellow stains around the edges.

Carpenter bees vs. honey bees

Many homeowners have trouble telling the difference between carpenter bees and honey bees or bumble bees. One is a menace to your home and your deck, while the other two are helpful creatures with important roles in our environment. You don’t want to chase honey bees and bumble bees out of your yard, especially if you have a gardenthese bees play an important role in pollination of flowing plants.

While there are tons of graphics and essays online comparing carpenter bees and other bees in appearance, it’s unlikely you’ll be able to get a good look at a bee in flight to determine whether it has a hard, shiny exoskeleton or is covered in fur. Hard exoskeletons are a characteristic of carpenter bees, whereas honey bees are furrier, and bumble bees are furriest. The best way to figure out whether a bee is a good bee or a bad bee is to watch where it goes. If your bee crawls into a wooden structure like your deck or into the eaves of your house, you’ve probably got carpenter bees.

Remember to be stealthy when observing your target bee to avoid stings. Male carpenter bees, though unable to sting, can be aggressive, darting at you threateningly and causing unnecessary panic. Female carpenter bees can sting, though they usually won’t unless they feel threatened. They will probably feel threatened if you try to pick them up or come too close to a nest full of their offspring. If what you’re looking at is a honey bee or a bumble bee, you’re in danger of getting a sting as well.

How do I get rid of carpenter bees in my deck?

Catching the infestation early

The good news is that if you catch a carpenter bee infestation early, you might be able to prevent major damage to your deck. Like many humans, carpenter bees don’t like to work hard if there’s a smarter, easier way to get the job done. Instead of creating new tunnels, carpenter bees often opt to simply re-enter old tunnels. This means that an average infestation generally has only a few tunnels to begin with, and a recent infestation probably won’t result in much damage to your deck’s structure.

However, if the carpenter bees are left to use the same tunnels over and over again for a period of years, they could weaken the wood and cause serious problems that require serious repairs.

Applying insecticides

Like other insects, carpenter bees are vulnerable to insecticides. Many homeowners use puffers to apply insecticide dust to the inside of the bees’ tunnel. These treatments are best applied before the carpenter bees begin their mating cycles, usually in spring. When the mating cycle begins, the carpenter bees come out of their tunnels and walk through the insecticide.

From there, the bugs’ days are numbered. If the mating cycle started before you noticed the infestation, two treatments may be necessary: the first in spring to kill the mating adults, and the second in late summer to kill their offspring. Applying these treatments at night is usually best since carpenter bees are active during the day, and you don’t want to get stung by a protective mother bee.

After you apply the insecticides, let them work their deadly magic for a few days, and then use wood putty or another filler to fill in their tunnels. Do this in the spring if you caught them before their mating cycle, or in fall after the second treatment if you needed to perform two treatments.

Building DIY carpenter bee traps

Growing concerns about pesticides’ effects on humans, pets, and the environment—including on helpful bees like honey bees—have caused many homeowners to consider alternative methods of carpenter bee control. Building a carpenter bee trap with a wooden box and an empty soda bottle is an increasingly-popular and surefire way to attract carpenter bees away from your deck and to their doom.

A DIY carpenter bee trap using a wooden box and soda bottle.
A DIY carpenter bee trap made of a wooden box and soda bottle. Source: HGTV Gardens

The steps to making and using this type of trap are simple:

  1. Drill half inch holes into a wooden box. These holes should be drilled at an upward angle to keep out sunlight, and one should be placed on the bottom of the box.
  2. Attach a clear bottle to the hole on the bottom of the box. You can recycle a soda bottle for this purpose! The bees will fly into the box and attempt to escape through the bottom hole, trapping them in the bottle.
  3. Once the bottle fills up, dispose of it and replace it.

A carpenter bee infestation does not have to be a death sentence for your deck. All insects can do major damage to a deck if left to their own devices, but preventative measures like choosing the right decking materials and finishes can go a long way in preserving your deck’s structural integrity and beauty. Taking the right steps to kill an infestation and prevent carpenter bees from retunneling could protect your deck from its formidable nemesis.

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Are you currently bee-proofing your deck? Have you successfully defeated a horde of carpenter bees? Share your strategies in the comments!

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