Subterranean Termites

Subterranean termites are the most destructive insect pests of wood in the United States. They cause more than $2 billion in damage each year, more property damage than that caused by fire and windstorm combined. Problems occur when termites attack the wooden elements of human structures -- homes, businesses and warehouses. Their presence is not readily noticed because they hide their activity behind wallboards, siding or wood trim.
After a termite colony matures, which requires from 2 to 4 years, swarmers are produced. Swarming usually occurs from January through April, during the daylight hours, usually after a rain. Environmental factors such as heat, light and moisture trigger the emergence of swarmers. Each species has a definite set of conditions under which it swarms. The number of swarmers produced is proportionate to the age and size of the colony. New colonies form when the old colony produces swarmers or when groups of termites become isolated from the main colony and establish subcolonies. This is called colony splitting. These subcolonies may exist independently or unite with the main colony. Subterranean termites derive their nutrition from wood and other material containing cellulose. Paper, cotton, burlap or other plant products often are actively attacked and consumed by termites. Subterranean termites cannot digest cellulose directly. They depend on large numbers of one-celled animals (protists) living in the termite hind gut to break down the cellulose to simple acetic acid, which termites can digest. Worker termites and older nymphs consume wood and share their nourishment with the developing young, other workers, soldiers and reproductives.
Termites are very attracted to odors of wood-decaying fungi that, through the decay process, make the wood easier to penetrate. In some instances, the fungi provide a source of nitrogen in the termite diet. Moisture is important to subterranean termites, which have very little resistance to dehydration. To survive, they must maintain contact with the soil (their primary moisture source) or other above-ground moisture sources, such as in structures with defective plumbing or guttering. Subterranean termites also must protect themselves from temperature extremes and attack by such natural enemies as ants and other insects. Termites foraging for food above ground protect themselves with shelter tubes, which are sometimes called mud tubes. Worker termites build the tubes from particles of soil or wood and bits of debris held together by salivary secretions. The tubes may be thinly constructed or large and thick-walled to accommodate many termites moving vertically between the soil and the food source.