How to Kill Powderpost Beetles


Powderpost beetles get their name from their dining habits. The larval forms of these insects bore into wood and reduce it to a gritty powder as they consume it. In their adult form, the beetles' glossy carapaces and reddish-brown to dark brown coloration make them resemble the wood on which their young feed. Like termites, powderpost beetles can be highly destructive to untreated wood, including building materials, fencing, antique furniture and wooden tool handles.

Things You'll Need

  • Boric acid insecticide
  • Spray bottle (optional)
  • Small brush
  • Paint (optional)
  • Wood sealant
  • Diatomaceous earth


  • Clean the affected wood, and examine it closely to determine the severity of beetle infestation. Powderpost beetles leave holes the diameter of small nails, tacks or pins and scatter their powdery frass -- the remains of destroyed wood -- around the holes. Severe infestations might require professional treatment or multiple boric acid treatments.

  • Mix the boric acid insecticide with water according to manufacturer's directions. If using a pre-mixed boric acid solution, shake the mixture thoroughly before using.

  • Pour the borate solution into a spray bottle that will turn the insecticide into a fine mist. If treating small wood items, a sprayer is unnecessary; dipping the items will be more effective. Powderpost beetles and their larvae are small, so an even dispersion of the insecticide ensures that the creatures get a lethal dose.

  • Test the solution on a hidden portion of the affected wood. Although non-toxic and typically non-staining, boric acid and other aqueous solutions might turn some wood finishes waxy or leave water marks.

  • Spray the affected area or wooden items thoroughly with the boric acid solution. If working with small implements like hand tools or small picture frames, briefly dip the entire item in the liquid.

  • Allow the wood to dry, then spray or dip the wood with a second round of insecticide treatment if the wood's finish occludes the solution or if the surface dries quickly; this might happen with old untreated wood.

  • Brush another layer of the insecticide solution on the most heavily infested areas with a small brush soaked in boric acid.


  • Let the wood dry for at least a full day after treatment.

  • Paint wooden surfaces if desired. Painted wood holds little appeal to powderpost beetles and other borers such as termites, so painting wood will prevent future infestations.

  • Coat painted or unpainted wood with sealant. Just as paint forms a barrier that the beetles' larvae will not penetrate, sealant also fills in the tiny gaps through which adult powderpost beetles gain entry into wood.

  • Scatter diatomaceous earth on and around untreated wood such as fireplace logs or unfinished lumber. Diatomaceous earth rips small insects apart on its jagged spines; to larger creatures, though, the substance is just harmless powder.

Tips & Warnings

  • Watch for further signs of damage. Stopping the pests sooner means preserving more wood, so examine treated furniture, lumber or building materials closely.
  • Avoid bringing untreated lumber or beetle-infested objects into contact with other wood.

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