Insects Burrowing in Wood Decks


Wood-burrowing insects consume wood or bore a tunnel system into decking to lay their eggs. Carpenter ants, carpenter bees, powderpost beetles and termites may all prove dangerous to wood decking and often cause considerable damage if not promptly treated. Homeowners should regularly inspect both the upper and lower portions of the decking to watch for possible invasion. The ends of the decking may also show signs of damage.

Powderpost Beetle

  • The larvae of the powderpost beetle (Lyctidae spp.), a small wood-boring insect that rarely exceeds 3/4 inch in length, damage wood decking and other wood products by burrowing into the interior. The larvae consume the wood as they dig along. The larvae make tiny holes across the surface of the wood decking. Within the intricate tunnel system, the larvae pupate and emerge as adult beetles in approximately one to five years. Adult powderpost beetles lay eggs within the holes on the wood or on the surface of the decking. They are nocturnal insects so homeowners rarely ever observe the adult beetles. The damage is found by observation of the holes.

Carpenter Ants

  • Carpenter ants (Camponotus spp.) are black or red and can measure up to 1/2 inch in length. The insects do not consume the wood decking, but they will create a tunnel system to reside within. The ants prefer moist wood and will often be found in areas of decking that already suffer rot. The ants will create satellite nests away from the main colony and they often choose wood that does not suffer any deformity to tunnel out and nest within. Watch for worker ants and evidence of infestation in the decking. If a colony is discovered in a dry wood location, continue to seek out the main colony, which will usually be located in an area of moisture and rot.

Carpenter Bees

  • Carpenter bees (Xylocopa spp.) look similar to large bumblebees in appearance with black and yellow coloration. Their bodies are lightly furred. The bees usually utilize existing holes to begin tunneling out a gallery to lay their eggs. On rare occasions, the female bee may decide to excavate a fresh tunnel system for egg laying. The female bee will continue to utilize the same tunnel system year after year to lay her eggs. The tunnels often become extensive and large. Carpenter bees will attack even pest-resistant woods such as cedar, cypress and redwood.


  • Termite (Isoptera spp.) damage in decking may go unnoticed by the homeowner until the damage is extensive. The insects live in large colonies within intricate tunnels and consume wood. The insects are predominantly attracted to moist wood that is easier to tunnel within and consume. Areas where the decking and soil come into contact pose the greatest risk of a termite infestation. Homeowners may notice flying termites in the spring, known as swarmers, which is often the first indication of an infestation.


  • Avoid using old or refurbished wood that may be infested with powderpost beetles. Use surface insecticidal sprays to help control the insects. Borate solutions have the ability to penetrate unfinished decking and offer control. Consider dusting carpenter bee holes and tunnels using an insecticidal dust to control the insects. Carpenter ants and termite infestations may require a pest removal specialist to control.

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  • Photo Credit Deck de madeira image by CarlosNeto from
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