Your house most likely was inspected before you moved in. It can be difficult to tell if your property is infected as termites can hide behind drywall or inside timber for years. Usually homeowners discover the presence of termites in the spring when they spawn and drones and new queens take flight or upon property inspection. There are two primary approaches to termite prevention: chemical and physical. For chemical barriers, you'll need to contact exterminators and your local building supply source. Laws regarding the chemicals you can use vary from place to place. Physical barriers are exactly what the name implies: an attempt to block termite access to your home. If you live in a region where termites are common, physical barriers will already be in place. Here in Queensland, Australia, houses are often built off the ground with metal flashing between the stilt and the timbers of the house. In other areas, metal flashing or screens might be in place and graded stone surrounds the house, including under the foundation. The most common way for termites to get in is when the physical barrier is breached. Someone might lean boards against the wall, build a deck or fence that comes in contact with the house, or earth piled up against the house will provide a bridge for infestation. The main idea is to maintain the physical barrier already in place. It's generally a good idea not to leave any untreated lumber around your property where termites can get at it. While termites near your home aren't necessarily cause for alarm, it's not a good idea to give them free meals. Annual inspections by someone qualified to spot infestation are a good idea in order to minimize the chances of costly property damage. New construction on your property needs to have the proper physical barriers in place or be built of termite resistant material.

There are some things that you can do with the yard which could help fend off termites, but they are pretty prolific critters and regardless of what measures you take -- you may want to have your home inspected occasionally. Benefitial nematodes sprayed on your lawn will often reach termites and "get them". Benefitial nematodes are little worms, almost microscopic, which attack larvae of insects. So, they will go after ants and grubs also. They prefer moist soil, as do termites. You may have to order them unless you find an organic gardening supply. The nematodes are often kept on a small sponge inside a sandwich bag and refrigerated until ready for application. They have a tough time with temperature extremes. There are thousands on that sponge. Mix with water and spray on a moist lawn, preferably when it isn't too hot. I would water-in. AntiDote is one trade name. There are also fungi which go after termites and other bugs. A "Beauveria bassiana" type fungis attacks some bugs. I haven't tried this product, but "Bio-Blast Biological Termiticide" appears to have good natural control. I personally think this would be a good bet. Diatomaceous Earth (d.e.) could help and it will also handle roaches and ants in your yard to some degree. I have heard of people applying this or boric acid to the interior wood wall supports. Don't use the swimming pool type d.e. Organic gardening places will carry the d.e. Of course there are the "plugs" with baits. You will see the do-it-yourself kits in some hardware stores. Many professionals utilize this safe method of control. Another safe treatment which can protect your home when it is being built is to treat it with a boric acid solution on the framing and some people use a mix of diatomaceous earth. Some builders now are helping termite control by applying a fine grain of sand as a barrier around and under the house. (It cuts up their bodies if they try to go through it.) Some places in the tropics put a tar or metalic undercoating around the house. These are safe methods which won't affect the health of your pets or family. A little sidenote: There are natural enemies to termites. Fire ants love them. There are fungi and bacteria. Having healthy soil around your place will help because of the microbe action and diversification. See some posts on soil and fertilizers. Once inside the house, I don't know of any other options other than a chemical insecticide. Often it is sprayed into the wall as a foam, and so is fairly well contained. There are lesser toxic types, which would be important to investigate. See my other posts for more information on a recommended approach that is least toxic. It should be noted again that some of these chemical termicides are extremely toxic and very pervasive. Read some of my posts on cancer. If you are building a new home, have the builder spray the lumber with a 10 to 1 ratio of d.e. to Boric Acid. There is no health hazard, but like all dusts, it is best to wear masks when spraying.

I second Tommys answer and will add Bait stations and annual inspection/treatment.