Termites invade any structure that contains wood, and the closer it is to the ground, the easier termites find it. According to the National Pest Control Association, American homeowners spend $1.5 billion yearly dealing with termites and their aftermath. Repairs alone average $2,500 per infested household.

Professional extermination costs a few hundred dollars to several thousand depending on the area affected and the treatment.

Unlike carpenter ants and beetles, termites can devour studs, joists and other structural components undetected until damage is extensive.


SPOTTING THE SIGNS

Three types of termites commonly affect U.S. households. Of these, subterranean termites are involved in more than 90 percent of infestations. Found everywhere but Alaska, they tunnel through dirt to find the wood, paper or cardboard all termites dine on.

Although drywood termites need not contact the ground, subterranean types must, which makes spotting them easier. Mud tubes are the most obvious giveaway. Usually found along foundation walls, these straw-like passageways allow termites to crawl upward along impenetrable objects unseen and impervious to the drying effect of the sun - lethal to these moisture-dependent insects. Termites can also travel within walls after entertaining through such vulnerable areas as wood support posts, porches and cracks in foundation walls. Once inside the house, they draw others to the spot with a scent trail.

Swarming is another sign of infestation. A good indication of a large colony, this dramatic event usually happens on a warm, damp day in early spring or summer as termite colonies send out reproductive males and feamles.

You'll see damage once termites have been at work awhile. Crumbling drywall, blistering paint, sagging doors or floors and loose or disintegrated window frames are all evidence of infestation. You'll also know they're at work when wood doesn't feel solid as you drive in a nail or if it sounds hollow when tapped or disintegrates when probed with a screwdriver.


KEEPING TERMITES OUT

An ounce of termite prevention is worth a pound of cure. It's also a lot cheaper.

First, remove all wood debris from you home, especially after new construction and remodeling. Strip form boards and grade stakes after construction. Keep lumber or firewood away from the house.

Termites need moist soil to survive. Thwart them by keeping gutters and downspouts in good shape and grading soil around the foundation of your home so it carries water away from the house.

If your home has a cinder-block foundation, cap the top tier of blocks with mortar to deny termites a dark, safe passage from the ground to wood sills and walls. Also, seal all foundation cracks.

Provide at least 14 inches of clearance between any wood part of your home and the soil. This lessens the chance of infestation and lets you quickly spot mud tubes.

For porches, set wood posts on concrete piers so they don't touch the ground. Install sheet-metal barrier skirts that make it hard for termites to reach the tops of posts.

Keep exterior veneers and stucco above grade level. This forces termites into the open and allows you to block their access to the framing structure of your home.

Ventilate basements and crawl spaces to reduce moisture.