How to Treat Wood Borers

Updated July 19, 2017

Wood borers are beetles whose larvae feed on wood.

There are two main types of home borer-beetle infestations. The common house borer beetles, lyctid beetles, are the hardwood-eating beetles, usually imported in egg or larva form from improperly treated construction materials or firewood. Long-horned beetles, more commonly known as old-house borers (which is not a description of the age of the wood they prefer), favour soft woods and are also imported from lumberyards; they often do not make their presence known until five to seven years after construction.

The larvae in both soft and hard woods will eat as they develop through the stages of becoming beetles. Once matured, they exit through the wood, leaving holes and dust (frass), that can be easily seen.

Visually inspect the suspected area by looking for fine, powder-like sawdust, called frass, coming out of tiny round holes in the wood.

Look for small black beetles on windowsills or walls near the suspected area.

Listen for a ticking-type sound coming from behind the walls, especially at night.

Tape masking tape over a 6-inch-square area of the wood that is suspected of infestation. Leave the tape on for up to two weeks.

Periodically, within the two-week period, look for fresh small holes that have been bored through the tape. This indicates an active infestation. If no holes are seen, it is an old condition and will not need to be treated.

Sand the entire area indicating borer infestation using a coarse sandpaper. This removes all the protective finishing on the wood, allowing the insecticide to seep into the wood's pores.

Brush or spray on commercial borate insecticide according to manufacturer's instructions. Borate is sold in either a power form that needs to be mixed with water and brushed on or as a premixed liquid spray.

Once treatment is dry, re-stain or repaint the treated area. The treatment will continue to work under this surface finish for up to 10 years.


Wood borers love moisture. If these insects are not imported through lumber transfer, adult beetles will be attracted to moist wood areas such as crawl spaces, floor joists and windowsills to lay their eggs. Inspect these areas once a year to manage moisture build-up. This type of infestation is hard to cure, so prevention is the best method of borer management. Using firewood quickly after bringing it into the house, removing and destroying dead trees near the home and inspecting any wood building materials before purchasing for wood borer holes or residual frass are good preventive practices.

Things You'll Need

  • Flashlight
  • Masking tape
  • Sandpaper
  • Borate
  • Floor finish
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About the Author

Sue Krippner started writing professionally in 2006, with work appearing in various online publications. After teaching high school art for several years, she became a licensed realtor and a certified home staging and interior redesigner. Krippner studied art history at Thomas Edison State College and advanced studio studies at the University of the Arts in Pennsylvania.