If you see the termites out side only, a bug zapper is a good option. Buy a zapper and hang it outside near where you see the termites. The termites are attracted to lights, so it's best to turn off all other lights besides the zapper so they will be drawn to it and killed.
But if you see more than a few flying termites inside the house, you will probably already be infested. There are some signs to look for as well such as mud in the basement, cracks int he foundation and siding. Also look for any dark and moist areas that have access to wood. These mud tubes are known to be a means of travel for these flying termites.
Killing the entire colony can prevent flying termites and their brood from causing damage. At the time you do find a colony, or even have reason to believe in it's existence, you should call an exterminator.
Liquid termiticide and baiting tend to be the surest method to kill these termites, it involves a good deal of various chemicals.
