Iowa Insect Information Notes

Drywood Termites

Drywood Termites

Although drywood termites are not native to the Midwest, they are occasionally found in Iowa in furniture transported here from the southwestern or southeastern U.S. Damage consists of large chambers and connecting small tunnels within the infested wood that are clean and smooth on the inside. Drywood termite damage is usually confined to the infested furniture though movement of the colony into the structure is possible. Structural damage to the point of weakness is uncommon though furniture may be completely ruined by the feeding action of the termites.

As the name implies, drywood termites establish in dry, sound wood that may have as little as 3 percent moisture content. They are not dependent upon a constant moisture supply as are the subterranean termites typically found in Iowa.

One of the common symptoms of drywood termite attack is the accumulation of tiny, straw-colored fecal pellets inside or beneath infested furniture. These pellets sift from small holes in the surface of infested wood or are pushed out through small round openings maintained by the termites for this purpose. The hard fecal pellets have six distinct, concave surfaces. Presence of pellets does not prove damaged wood is currently infested, as pellets continue to sift from furniture for many years after termites are controlled or die. However, large, consistent accumulations of pellets are a convincing sign the termites are still active.

Options for drywood termite control: First, evaluate the level of infestation and the value of infested furniture to decide if the furniture should be discarded or treated. If you decide to salvage infested furniture you may choose to hire a pest control operator. Insecticide dusts such as boric acid can be "injected" or "puffed" into the termite galleries either through existing holes or though small holes drilled through the wood surface. This method is time consuming and laborious and not particularly effective, though with persistence, small infestation can be eliminated.

Pest control operators have available pressurized aerosol injectors that allow liquid insecticide to be injected into infested wood. This method is highly effective but is generally not available to homeowners. Similarly, fumigation in a vault or tarp is an option only available to professionals. Temperature extremes may be a practical alternative. Infested furniture (or pieces) that can be heated to 120 degrees F for several hours will be free of termites. Similarly, a rapid lowering of the temperature (from room temperature to below freezing) may eliminate the termites. This could be accomplished by moving the furniture to a large, walk-in freezer or waiting until a very cold winter day and moving the furniture from a warm house into a garage or unheated porch for several days.

Updated 07/14/2005 - 2:49pm