Native Subterranean Termites
Most pest species of subterranean termites in North America belong to the endemic genusReticulitermes. Reticulitermes species are found in every state 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. Its counterpart, the western subterranean termite, Reticulitermes hesperus Banks, is found along the entire Pacific Coast ranging from southern California to British Columbia. Reticulitermes tibialis occurs in the inter-mountain region of the West. In addition to Reticulitermes flavipes, two other Reticulitermes occur in Florida,Reticulitermes virginicus, and Reticulitermes hageni.
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.
Flight seasons differ among the three Reticulitermes species in Florida. Reticulitermes hageni alate flights begin in early December and last until early February while Reticulitermes flavipes flights start in early January and end in April. Dispersal flights of Reticulitermes virginicus occur between early February and late May. Swarming by Reticulitermes flavipes and Reticulitermes virginicus occurs during warm, sunny and windless afternoons usually after rain, while Reticulitermes hageni alates swarm at night.
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 screw driver 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. Reticulitermestend to cover the wood they feed upon with soil, thus giving wood a more “dirty” appearance thanCoptotermes formosanus-infested wood. However, it is not advisable to identify the termite species based solely on damage as there are many exceptions.
Preventive practice. 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. Currently available termiticides include permethrin (Dragnet® FT, etc.), cypermethrin (Demon® TC, etc.), bifenthrin (Biflex® FT, etc.), imidacloprid (Premise®, etc.), chlorfenapyr (Phantom®), chlorantraniliprole (Altriset®), and fipronil (Termidor®, etc.). Pyrethroids such as permethrin, cypermethrin, bifenthrin, and fenvalerate repel termites from treatment barriers, while other termiticides prevent termite invasion by lethal contact.
Physical barriers. Mirroring the safety concerns of some soil termiticide barriers, two physical barrier types, uniform-sized particles and stainless steel screening, have been employed as non-chemical controls in recent years. When used as continuous horizontal barriers installed during pre-construction installation, these physical barriers withstood intensive foraging activities of several termite species under field conditions (Su and Scheffrahn 1992, Lenz and Runko 1994). These non-chemical barriers are semi-permanent and can be readily installed during construction. Their physical presence, as opposed to the less visible chemical barriers, also provides ease for verification by regulatory inspectors.
(Courtesy of Featured Creatures )