Termites tunnel from their home in the soil in a constant search for wood to eat. But they can't tell the difference between a dead tree and your house. If they come across your home's foundation while foraging, they'll follow any cracks or crevices into your home. They may enter through wood in contact with the soil or by building pencil-sized mud tunnels from ground levels, to where the house's wood frame begins.
Termites can also enter your home through expansion joints or utility and plumbing openings in the foundation. And they are small – all they need is an opening 1/32-inch wide to squeeze into your home.
Chances are, you won't actually see termites or a termite swarm, which lasts less than an hour. More likely, you'll see evidence of swarming; sudden appearance of winged termites; piles of small, lacey wings; or mud tunnels termites build.
Under ideal conditions, a typical termite colony (with 250,000 workers) can eat about 20 feet of a 2 x 4 board per year. If you find evidence of an infestation, there's no need to panic. It's unlikely the damage will get much worse from the time you first discover termites to the time your home is treated. Still, stopping the destruction sooner rather than later is important in avoiding costly damage and repairs.
There are a variety of termites in the United States but they all have one thing in common; when left alone, they'll eat you out of house and home. The most common variety, subterranean termites, consist of a queen, king, reproductives, workers and soldiers.