Determine the type of termite you are dealing with. Subterranean termites (the most common type), dampwood termites and formosan termites can all be treated with liquid insecticide or bait. Drywood termites often require fumigation.
Divert any downspouts and gutters as far away from the landscape timbers and house as possible.
Apply the liquid termite treatment to your lawn as directed. Usually they are sprayed around the house and affected areas, killing any termites that they contact directly. For a safer, more environmentally friendly option, use orange oil. Orange oil is made up of a chemical called d-limonene that is extracted from orange peels. It is harmful to insects, but has very low toxicity toward mammals.
Apply termite bait to the affected areas as directed by your specific product. Termite baits are picked up by the workers and will gradually kill off remaining members of the colony.
Rid your yard of infected timbers. If badly damaged, these timbers will serve as an ideal home to another colony. Treat your new timbers with borate. This treatment is applied like a coat of paint. It works because termites are dependent upon little protozoa to break down the wood into useful nutrients within their digestive tract. Borate kills the protozoa, thus forcing the termites into starvation. However, it will not be able to eliminate an entire colony alone.
Eliminate any wood completely from your yard. To give your property the best chance to stay free of termite infestations, use stone or synthetic wood in place of traditional wood landscape timbers.