Most pest species of subterranean termites in North America belong to the endemic genus Reticulitermes. Reticulitermes species are found in every in the continental United States except Alaska, but are most common in the warm and humid southeastern region. The eastern subterranean termite, Reticulitermes flavipes is the most widely distributed and is found in the entire eastern region of North America as far north as Ontario, Canada, and south to Key Largo, Florida.
Because of their cryptic nature, structural infestations of subterranean termites are usually not visible. Most people become aware of an infestation when annual flights of winged termites (called alates) occur in structures. The alates of Reticulitermes flavipes and Reticulitermes virginicus are dark brown, while those of Reticulitermes hageni are yellowish brown. Alates of Reticulitermes flavipes are generally larger (approximately 0.4″ long including wings) than those of Reticulitermes virginicus or Reticulitermes hageni (approximately 0.3″ long). Alate wings of Reticulitermes species have two hardened and thickened veins that are visible along the entire front end, but lack the small hairs that are characteristic of the Formosan subterranean termite, Coptotermes formosanus Shiraki. After indoor flights, most alates are found dead near windows or in sinks and bath tubs – usually with their wings still attached.
Because termites consume cellulose, the main structural components of plant cells, any wood material in a house is a potential food source, but they may also damage non-wood material in search of food. Because termites rarely show themselves in the open, infestations can be difficult to detect until damage becomes severe. In addition to the presence of alates and shelter tubes, wood material can be probed with a screwdriver or ice pick to locate infested wood. The surface of severely damaged wood may appear blistered or peeling, as termites hollow out the wood leaving a paper-thin surface. Reticulitermes tend to cover the wood they feed upon with soil, thus giving wood a more “dirty” appearance than Coptotermes formosanus-infested wood. However, it is not advisable to identify the termite species based solely on damage as there are many exceptions.
Because subterranean termites forage in soil, it is important to keep structural lumber from direct contact with soil. Keeping the lower foundation walls and siding clear of vegetation or mulch makes it easier to inspect for termite shelter tubes. Subterranean termites need moisture for survival. Leaky plumbing, air conditioning condensate, and any portion of a building and its perimeter that collects excessive amounts of moisture should be corrected to maintain an environment less attractive to subterranean termites.
Soil Termiticide Barriers
Spraying the soil beneath the foundation with liquid insecticides has been the traditional method for subterranean termite control. The objective is to place a chemical barrier between termites and the structure to be protected. Before the foundation is poured, soil termiticides are applied onto sub-slab soil to form a horizontal barrier. A vertical barrier is applied around the perimeter after the foundation is poured. This pre-construction treatment is mandatory in many of the United States. Post-construction treatment consists of drilling holes through slabs and injecting insecticides under the foundation and by drenching trenches dug along building foundations.