Prevention Is the Best Way to Deal With Invaders

Here are some pointers for preventing termite infestation in existing homes:

* Subterranean termites need a damp environment to survive. Repair or remove sources of moisture: leaky roofs, pipes or air conditioners; correct poor drainage; take care not to over-water plant boxes and get rid of standing water.

Be especially vigilant about keeping attic and foundation areas dry. Slope the ground next to your foundation so that it carries water away from the house.

Remove any wood in contact with soil. Eliminate wood debris around or beneath your home, including scrap lumber, tree stumps, grade stakes and mulch. Don’t stack firewood or place wooden trellises against the house.

Where wood does contact the ground, treat it with chemicals or borates or use pressure-treated lumber.

Support wooden steps or fence posts on a concrete base.

Cut back shrubs, vines and bushes from foundations and walls.

* Drywood termites look for any opening into your home. Seal all knotholes and cracks on the exterior and screen all vents.

Before you build: If you’re constructing a new home, the soil underneath your concrete foundation should first be sprayed with a pesticide.

For a nontoxic approach, physical barriers include termite shields, which are metal strips bent into an “L” shape that are laid across the tops of foundation walls, and a special sand (the kind used in sandblasting) that termites can’t tunnel through, applied under concrete slabs or in crawl spaces along foundation walls.

A stainless steel mesh barrier, available only in Hawaii now but soon to be marketed on the mainland, is extremely effective in keeping out termites, according to Brad Kard, principal research entomologist with the U.S. Forest Service at Mississippi State University.

The mesh is best used for preconstruction underneath homes, he said, but special adhesive strips can “glue” it to concrete, brick or other surfaces or it can be wrapped around the bottom of fence posts.

Also on the horizon, Kard said, are chemically treated “vapor barriers.”

Because concrete is porous, the soil beneath foundations is usually covered with a plastic sheet, or vapor barrier, to keep out moisture. The soil is normally sprayed with a pesticide before the plastic goes over it. The vapor barriers now being tested incorporate the pesticide in the plastic instead. The pesticide lasts longer and doesn’t get into the soil.