The Subterranean termites cause more than $750,000,000.00 in damage each year. Subterranean termites are by far the most destructive of all wood destroying insects. Termites strike five times as many homes as fire and do more economic damage than all tornados, hurricanes, and wind storms, combined. They have the longest life span of any household pest; under favorable conditions, individual termites may live up to 15 years, and colonies may exist in dwellings for considerably longer periods. Because termites eat, breed, and move in their sealed passages, they frequently leave the surface of the wood intact, so the first indication of their presence may not occur until the wood is so weakened internally that it breaks away.

Subterranean termites must live in an atmosphere possessing constant temperature and favorable humidity. To achieve these conditions, they build airtight tunnels or passages from their nest to their feeding places. The tunnels are made by the workers from wood or soil particles cemented together with saliva and fecal material. A knowledge of these behavioral characteristics of termites is fundamental in achieving effective control. These termites are extremely tenacious. They move up masonry walls or piers by building enclosed tunnels (mud tubes). Even when metal caps and termite shields are placed over piers and foundation walls to prevent them from reaching the wood, they have been known to exude an acid which eats away the metal so that they can proceed.

Subterranean termites are social insects living in colonies in the soil. The members of these colonies are divided into several castes. The first cast includes the queens - a primary one and sometimes several secondary ones - and a fertile male paired with the primary queen. The wingless and sterile worker caste constitutes the largest number of individuals in a colony. In doing so, they construct tunnels over masonry and form galleries in the wood in which they are feeding. Another sterile caste in the colony are the soldiers, which are fed by the workers and must protect the colony from attack by invaders such as ants.

Once a year, usually in the spring, a winged reproductive caste develops. A single colony may produce several hundreds of reproductive, often referred to as swarmers. On a day when conditions are favorable, they leave the colony as a swarm. After flying a short distrance, the swarmers fall to the ground, break off their wings, and locate mates. A new colony is formed in a suitable area of damp soil beneath a rock or wood.

As you would expect, inspecting for signs of termites isn't a hit or miss proposition. Sometimes the signals are impossible for the untrained eye to detect. And most always, they are in places very difficult to reach. Worse, there are instances when termites are present but cannot be seen because the areas are inaccessable or simply obstructed from view. Consequently, every inch of the building that comes in contact with the soil must be checked if at all possible. Concrete and masonry walls and floors must be examined for cracks or gaps through which termites could enter. The entire structure must be inspected for indications of hollowed out, weakened wood, and especially for signs of mud tubes through which they can reach wooden structural members. Mud tubes on masonry walls or on support piers are evidence of an infestation. Wood damaged by termites has galleries that tend to run with the grain. The galleries formed by subterranean termites can be distinguished from damage by other wood destroying insects because often they contain particles of soil rather than saw dust.

Termites need constant moisture to survive; thus colonies are usually located in the soil. The workers leave the colony to forage, but must return to the soil at least every 24 hours for moisture. Sites where wood floors, beams studs, or joists are in close contact with damp soil, such as under dirt filled porches, or in crawl spaces, provide easy access between the colony site and their food supply. Further, where there are water leaks in the building, such as leaking pipes, the constant damp wood may enable secondary colonies to be formed in the building itself.

The subterranean termite's need for constant moisture is a characteristic that can aid in the control of these insects. By breaking the wood/soil contacts, reducing moisture prone areas, and/or installing a physical or chemical barrier between the soil and the wood, a structure can be protected from termite infestation. A chemical that is toxic to termites can be placed in the soil, or they may die in the structure when they cross it to return to the soil, or they may die in the structure from lack of moisture. The chemical obviously should be effective, toxic, and non-repellant, and provide a residual barrier for many years.

- information obtained and/or paraphrased from Dow Chemical Termite Resource Manual and Termite Handout Booklets