After a termite colony matures, which requires from 2 to 4 years, swarmers (also known as reproductives) are produced. 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.
Both male and female swarmers fly in pairs from the colony and travel varying distances. They are extremely weak fliers; wind currents usually carry those that travel any distance. Only a small percentage of swarmers survive to develop colonies; the majority fall prey to birds, toads, insects and other predators. Many also die from dehydration or injury.
A pair that survives lands and immediately seeks cover under rocks or other materials. The pair makes a very small nest before mating. Initially, the new queen termite lays only a few eggs. The male, or king, remains with the female because periodic mating is required for continued egg development.
Eggs are not deposited continuously; in fact, only a few hundred are deposited during the first year. In subsequent years, the young queen grows larger and lays more eggs. Larvae hatch from the eggs within several weeks and are cared for by the new king and queen. The larvae molt into pseudergate workers, and then into presoldiers or brachypterous nymphs. The colony stabilizes when the queen reaches maximum egg production. If the queen dies, secondary reproductives take over the queen's duties.
The maximum size of a colony depends on such factors as location, food availability and environmental conditions, especially temperature and moisture. Some colonies remain small; others contain up to hundreds of thousands of individuals.
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.
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 muddings or leads. 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.
This construction material also is found lining the galleries built in wood being attacked and aids in identifying termite-damaged wood. Shelter tubes often are used to bridge masonry or other objects, allowing termites access to a food source (wood) above ground.