Subterranean termites live underground or in protected areas such as wood. Termites do not "attack" your house. They forage, attracted by moist areas, and find food sources. Termites do a very good job of breaking down cellulose in the soil.
When termites discover your home, they become a real pest and that is where a professional pest control company comes in. During spring in most areas of the country, healthy subterranean termite colonies will "swarm," or send out winged reproductive termites to start new colonies. The swarmers are darker in color, some species almost black, and have four wings. One frequent question is how to differentiate termites from ants. Ants generally do not swarm the same time as termites, but it can happen.