Formosan subterranean termites

Photo by ęScott Bauer

The Formosan subterranean termite is native to China. It has been introduced into Japan, Guam, Sri Lanka, South Africa, Hawaii, and the continental United States. In 1965, it was first discovered in the continental United States at a Houston, Texas, shipyard. In 1966, well established colonies of the Formosan subterranean termite were discovered in New Orleans and Lake Charles, Louisiana, and Houston and Galveston, Texas. In 1967, it was found in Charleston, South Carolina. Well-established colonies were detected in Florida in 1980, 1982, and 1984 (Oi et al. 1992).

Ships have facilitated the introduction and spread of the Formosan subterranean termite throughout the world. Once introduced, swarming is the termite's natural method of spread. Since the Formosan subterranean termite is a weak flier and does not spread rapidly by itself, the movement of infested soil or material such as lumber, wooden crates, or other wooden products is another important method by which it spreads. These termites are commonly associated with the railroad ties used for landscaping.

In the United States, the Formosan subterranean termite generally has been confined to the southeast at about 32.5oN latitude. This latitude coincides with the warmer temperatures usually associated with this termites. However, the widespread use of central heating in the United States may encourage the spread of the Formosan subterranean termite. Central heating provides a warm environment conducive to the survival of termites during winter.

Major swarms of the Formosan subterranean termite begin in May or June and last until about July or August. On humid, still evenings, usually around dusk, large numbers of swarming alates can be seen around light sources. They are attracted to light.

After a short flight, alates drop to the ground, shed their wings, and pair off. If they successfully find a small crevice containing moist wood, the pair forms a chamber and lays eggs. It usually takes 3 to 5 years to develop a mature colony. A mature colony can contain between 1 to 10 million termites, and its foraging territory may cover 38,500 square feet.

Like other termites, Formosan subterranean termites feed on cellulose. Cellulose is the major component in wood and paper products. In addition to feeding of the wood in our homes, they have attacked more than 47 species of living plants including citrus, wild cherry, cherry laurel, sweet gum, cedar, willow, wax myrtle, Chinese elm, and white oak. Formosan subterranean termites attack the bases of poles, old tree stumps, or other wood in contact with soil. They can construct galleries to the upper stories of buildings to feed on the wood.

Formosan subterranean termites have also been known to attack (but not eat) non-cellulose material such as thin sheets of soft metal (lead or copper), asphalt, plaster, mortar, creosote, rubber, and plastic in search of food and moisture. However, their highly publicized ability to chew through concrete is a fallacy. Instead of chewing through the concrete, Formosan subterranean termites are uncanny in finding small cracks in concrete that they use as foraging routes.

Formosan subterranean termite nests are made of "carton" that consists of chewed wood, saliva, and excrement. Nests can be constructed in the ground or aerially (no ground connection). Auxiliary nests are often constructed in the food source, tightly filling wall voids or chimneys. Formosan subterranean termites can produce tightly packed, massive carton nests. Native subterranean nests generally are more loosely constructed and smaller.

Faith M. Oi, Former Extension Entomologist, Assistant Professor Thomas G. Shelton, Graduate Research Assistant Auburn University
Wood destroying

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