There are more than 2,000 species of termites across the world and about 50 of those live in the U.S. Of those 50, three types of termites are especially known for causing problems for homeowners. Subterranean termites are the most common type in the United States, and there are several species of this termite in the country. These termites build nests in soil because they require the moisture from the ground to survive. They then migrate upward to feed on the wooden components in homes. Subterranean termites are found in every state except for Alaska. Formosan termites, in particular, are known for causing significant structural damage because their colony sizes are so large. These insects are actually a type of subterranean termite. They typically start on the surface, but quickly drill into the wood and leave much of the outer surface for protection. Mud tubes seal up any openings to help maintain favorable humidity and temperature. For the most part, however, they remain hidden inside walls or behind other building materials. Formosan termites are found in many southeastern states, along the Gulf Coast and in Hawaii. Drywood termites don't require moist soil to thrive — instead, they get the moisture they need from wood they ingest. They're most often found in states with milder winters, including southern California, Arizona, New Mexico, Texas, Louisiana, Alabama, Georgia and Florida. Drywood termites may establish several colonies in one home and are known to infest wooden framing, flooring and furniture.