Wood Borer Damage in Hardwoods

- Certain beetles can damage wood floors, cabinets and furniture -

Summary: Larvae of beetles in the family Lyctidae develop in wood where they feed on starch stored in specialized cells. These "powderpost beetles" can cause significant damage because new generations may re-infest the wood thus expanding the damage over time.

Jack DeAngelis, PhD
OSU Ext. Entomologist (ret.)

Wood borers damage hardwood

Hardwood flooring, cabinets and furniture can be infested with the larvae of wood boring beetles called powderpost beetles, or woodworms, (see What are Powderpost Beetles?) belonging to the family Lyctidae (see photo right). There are other insects that damage wood (see Wood Destroying Insects) but only powderpost beetles are capable of re-infesting the wood from which they emerge. This is important because it is this "cycle of infestation" that leads, over time, to significant subsurface damage.

Beetle larvae bore through wood fibers in order to find starch stored in dead wood cells. As wood ages its starch content declines but even well seasoned wood often has enough starch to support powderpost beetle larvae.

powderpost beetle larva (woodworm)

powderpost beetle larva (enlarged) - head is toward right

Larvae develop over months, or even years, depending on starch and moisture content of the wood, eventually emerging as adult beetles. Emergence holes (sometimes called flight holes) and powdery boring dust are usually the first signs of a beetle infestation. Adult beetles mate and the females lay eggs on the surface of wood. Larvae hatch and bore into the wood to start the cycle again. Wood flooring and cabinets can be safely and inexpensively treated during installation to prevent new infestation. Treatment after installation is more complicated and expensive but is still possible.

Damage can be extensive

Two kinds of damage: First, emergence holes detract from the wood's appearance. While a few holes may add to "patina", a lot of holes can be quite disturbing.

More serious damage occurs below the surface. As larvae bore in search of food they weaken the wood. Eventually the wood may be crumble. Wood flooring that has a manufactured surface (laminate flooring) is especially susceptible to damage because thin laminates can easily crack if not supported from below.

The first question is "is the infestation active or inactive". If the damage is old and there is no longer an active beetle infestation then no treatment is necessary. It is fairly common to find old damage from a beetle infestation that had died out years before (see How to Tell an Active From Inactive Infestation). If you uncover an active infestation in an existing floor you'll need to decide if treatment is necessary and how to treat it (see Treating Powderpost Beetle Infestations).

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