There are seven different types of termites existent worldwide. Of those, there are only three families that are of structural significance in the United States. These are the subterranean termites (Rhinotermitidae), the drywood termites (kalotermitidae), and the damp wood termites (termopsidae). Of those, there is only one that is commonly of structural importance in North Carolina; the Subterranean Termite.
Most subterranean termite colonies consist of three different castes or types of termites: the reproductive caste, the soldier caste, and the worker caste.
The reproductive caste consists of the king, the queen, supplementary reproductives and the alates. Their job is to produce more termites or start new colonies. Most people only encounter the alates. These are winged termites, and while most termites are lacking pigment and white in color, these are pigmented and dark in color. This pigmentation helps protect them from the UV rays of the sun, so they can perform the one job they were created for. That job is to fly as far from the current colony as they can, pair up and start a new colony.
The soldier termites have larger heads with noticeably enlarged mandibles and perform one function: to protect the workers and the colony from predators.
The workers are white and perform all the work, including consuming wood and feeding it to the rest of the colony. They are the ones that cause all the damage. They are constantly moving up, entering the wood, feeding, and then moving back down into the ground to feed the other termites by means regurgitation, also called trophallaxis.
There are statistics on the rate at which a specific species of termite colony feeds; however, these are misleading as they are “sterile” numbers. That is to say, the data was collected under specific conditions that don’t always exist in the field. The rate at which damage occurs is affected by the ambient temperature, colony size, how many competing food sources there are, number of colonies infesting the structure, species/hardness of wood, wood moisture content, etc. Treatment typically involves treating the soil they pass through, using baits, adding exclusion devices to prevent access, or treating the wood itself.