Protecting Your Deck Against Carpenter Bees

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Protecting Your Deck Against Carpenter Bees


Wood decking is prone to insect damage; softwoods being the most vulnerable. Taking the right precautions, wood can be protected against this danger. A common solution is the use of hardwoods and pressure treated woods to help deter insects, but they’re still prone to being drilled by carpenter bees. So, what about composite decking? Can a composite deck better resist insects because it’s not 100% wood?

Eek! A carpenter bee! Hope his friends aren't close behind.

Carpenter Bees and Your Deck

Whether your property has a deck or fence, you may have already seen nickel-sized holes appear. Most likely this is the result of carpenter bees drilling holes in order to build their nests. Typically these bees drill an inch deep into wood before making right angles to begin drilling with the grain of the wood. The female bees then lay their eggs in individual chambers and aggressively stand guard at the entrance of the nest when complete (only females have stingers!), leaving only to forage for food. While the damage from an individual carpenter bee is minimal, it becomes an issue when the larvae start to emerge. If unable to exit from the original hole, the new carpenter bees will drill new holes, creating a much larger issue. On top of this, these bees typically return to the same wood or relative location year after year. These holes, once abandoned, provide homes for other wood eating insects like carpenter ants and termites. Left untreated, you can expect the following damages to occur:


  • Structural Damage – With carpenter bees returning to the same locations, damage can start out as minimal, but increase exponentially. This can become a safety issue leading to deck boards or supports breaking under pressure.
  • Water Damage – Once bees drill holes, your wood or composite material becomes more exposed to moisture leading to mold and rotting.
  • Stains – The most unattractive part of having carpenter bees are the stains they leave from their waste. If you are seeing yellow/brown stains near your home’s siding, fence, or decking, it’s a good indicator that you have carpenter bees.
  • Woodpeckers – Carpenter bee larvae are actually loud enough to be detected by woodpeckers. Leave the problem untreated long enough and you could be inviting a far more destructive guest.


Wood, Composite, or PVC?

Fortunately if you have already installed composite or PVC decking, you are less susceptible to insect damage. Composite materials are made of a combination of wood and plastic, and different brands have varying amounts of each ingredient; PVC is completely plastic. Typically the higher ratio of plastic to wood used in building materials will create a more dense product, equalling a greater resistance against all damage. Carpenter bees are far less likely to continue to drill into dense wood materials when there are softwood materials nearby. While composite and PVC materials have become greater in demand, wood decks are still the most popular.


Dealing With Carpenter Bees

Ultimately, using harder materials will lower your chances of insect damage. PVC is your best Hopefully this guy will stay away from the deck.choice since it isn’t made with wood; using a composite material would be your next best choice. For many, the look and feel of a wood deck is not something they’re willing to sacrifice. This doesn’t mean you have to deal with carpenter bees, and with the right supplies you can help make your deck more bug-resistant. Here are the steps you should take in preventing and getting rid of carpenter bees:


  • Be Aware – Watch for signs of carpenter bees during the early to mid-spring. Three obvious signs are half-inch sized holes, sawdust, and dark yellow splatter stains.
  • Treat Active Holes – If you have active holes, it’s best to wait till night before you treat them as bees rest during this time. To treat the problem, the best solution is to use insecticidal dust along with a duster to coat the entrance and inside walls of the tunnel. Leave the hole open to allow for emerging bees to come in contact with the insecticide and spread the dust. If you plug the hole too early, the larva will dig new holes to get out. For more severe infestations you may have to spray again a month later.
  • Fill Abandoned Holes – Once all the bees are dead, it’s safe to fill the hole during the middle of fall with caulk or putty. Painting over these spots also helps deter future infestations.
  • Prevent – Carpenter bees typically are attracted to unfinished woods, cracks, and previous holes. Paint or varnish unfinished wood before the spring season to help deter bees. Use residual insecticides on areas that may be at danger.

New Deck Free Guide

Bug Off!

Carpenter bees can be a threat to your deck, but with the right precautions and choosing the right material, you can stand a chance. In many cases, carpenter bees should not deter you from getting a wood deck as long as you plan to bug-proof it every year. Doing some reasearch on your location can also reveal how prone your area is to bee infestations. In worst case scenarios PVC and composite decking are both alternative options for those looking for less maintenance.


  • Elizabeth Herman says:

    I have just put in a new deck. Is paint better than wood stain in deterring carpenter bees?

  • fixwix says:

    very helpful post thanks for sharing.

  • Eric says:

    I put in New wood deck with treated lumber, stained it. Then will cooking out I noticed these large bees . So I watched them drill there hole. How cool that her drilling that perfectly round hole. Then one day ask my wife to stop hammering for awhile. She said she wasn’t and ask me to stop . So next time I was on it ,the biggest red hooded woodpecker I had ever seen was pounding away to get to larva. Needless to say his hole not so cute. He tore threw the board like know bird I’ve ever seen. That is one big read head almost as big as our hawk that lives near by.

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