The Formosan Subterranean Termite

Brian T. Forschler - Department of Entomology, University of Georgia, Georgia Experiment Station, Griffin, GA 30223.

Introduction

The Formosan subterranean termite, Coptotermes formosanus (Shiraki), was first described as a species in 1909 from specimens collected on the Asian island of Formosa. It is now generally accepted that the termite is native to China and it is Formosa. It is now generally accepted that the termite is native to china and it is considered a serious structural pest whenever it occurs. The Formosan subterranean termite has been found in Japan, Sri Lanka, Phillipines, Guam, Hawaii, South Africa and the continental United States. Although officially reported in Hawaii in 1913, newspaper reports indicate that the termite was on the island as early as 1869. The first report of the Formosan termite in the continental U.S. was from a Houston shipyard in 1965. It was reported in Louisiana in 1966 and Charleston, S.C. in 1967, although specimens collected in Charleston in 1957 indicate that the termite was introduced nearly ten years earlier. In the past 15 years the Formosan termite has been identified in Broward and Dade counties in Florida (1980-3). Mobile, Lee, and Baldwin counties in Alabama (1985-87), Memphis, TN (1985), North Carolina (1990), San Diego, CA (1991), and Atlanta, GA (1993). It is believed that these infestations were transported in infested building or plant materials from areas where the termites were well established.

Biology

As with the native subterranean termites, Formosan termites initiate new colonies by sending out winged reproductives (alates) from established colonies. The Formosan swarms occur from May to June in Florida and Louisiana and from May to July in South Carolina. Formosan termite swarms occur from dusk to midnight and the alates are attracted to lights. After a short flight (usually not more than 20-50 yards) the alates lose their wings, pair off, and seek a small crevices in moist wood to begin the new colony. It takes 3-5 years for a mature colony to develop from a queen, which lay approximately 2,000 eggs/day. Mature colonies can have a population of 10 million foraging workers, soldiers, a primary queen, and several secondary reproductives. The foreaging territory of a mature colony can occupy several thousand square feet.

Destructiveness

The Formosan termite is known to attack over 50 species of living plants as well as structural lumber. A survey in New Orleans showed that 10% of the utility poles in the city are infested with the Formosan termite. This termite is often described as aggressive in both its feeding habits and foraging tenacity. They cannot eat through concrete but have been known to attack non-cellulose materials like plastic, asphalt, and thin sheets of soft metal. Although laboratory studies indicate that the individual Formosan termite eats slightly more wood than the native subterranean termites the larger colony populations found with this termite can cause severe structural damage to unprotected homes in 2 years.

The Formosan subterranean termite usually enters structures from colonies maintaining contact with ground to provide the necessary moisture requirements. However, the Formosan termite, more than the native subterranean species, is able to initiate colonies, which have no ground contact (aerial colonies). It is estimated that 25% of the infestations in southeast Florida have no ground contact. In contact, native subterranean form aerial colonies only in rare instances (less than 1%).

Recognition

Damage: The damage caused by the Formosan termite is similar in many respects to the damage done by native subterranean termites. Termite feeding will follow the grain in a piece of structural lumber but the Formosan termite is more likely to feed on both the summer and spring wood leaving a larger hollow space in the damaged lumber. Native subterranean termites usually fill their feeding galleries with soil and excretement whereas the galleries of the Formosan termite are cleaner, practically soil free and covered with whitish spots. In severe infestations Formosan termites will fill hollow spaces, or even wall voids, with a combination of termites excrement, macerated wood, saliva and soil. This material called carton can be used by the Formosan termite to form nest-like structures and is unique to the Formosan termites. Carton nests are constructed in or near the feeding site and a single colony may have several of these auxiliary nests – each containing secondary reproductives.

Insect Identification: Three casts forms of subterranean termites are often found at the site of an infestation; alates, soilders and workers. Only the alates and soilders can be used for identification.

Alates - Below is listed a comparison of Formosan alates and the three native subterranean species found in Georgia.

Soldiers - Soldier of the Formosan termite have an oval shape head compared to the oblong shape of the native subterranean soldiers. In addition, the Formosan soldiers have a well developed fontanelle which forms a tube-like structure located on the front margin of the head just above the mandibles. When disturbed the soldiers emit a milky white fluid from this opening whereas native termite soldiers do not eject any noticeable substance. The proportion of soldiers to workers in native subterranean termite colonies is approximately 1-2 to 100 (1-2%) in contrast to the Formosan termite colony which contains 10-20 soldiers to every 100 workers (10-20%).

Soldier Head

Native Subterranean Termite	Formosan Subterranean Termite

Alate Wings

Native Subterranean Termite	Formosan Subterranean Termite

References

Chambers, D.M., P.A. Zungoli, and H.S. Hill Jr. 1988. Distribution and habits of the Formosan subterranean termite (Isoptera: Rhinotermitidae) in South Carolina. J. Econ. Entomol. 81: 1611-1619.

Spink, W.L. 1967. Formosan subterranean termites in Louisiana. La. Exp. Sta. Circ. 89

Spronsler, R.C., Jordan, K.S. and A.G. Appel. 1988. New distribution record of the Formosan subterranean termite, Coptptermes formosanus (Isoptera: Rhinotermitidae) in Auburn, Alabama. Ent. News 99: 87-89. 5 pp.

Su, N-Y. And R.H. Scheffrahn. 1988. The Formosan subterranean termite. REC Research Report FL 85-1. 5 pp.

Su, N-Y. and R.H. Scheffrahn. 1987. Alate production of a field colony of the Formosan subterranean termite (Isoptera: Rhinotermitidae) . Sociobilogy 13: 209-215.

Thompson, C.R. 1985. Detection and distribution of Formosan Termites (Isoptera : Rhinotermitidae) in Southeastern Florida. J. Econ. Entomol. 78:528-530

Yates, J.R. and M. Tamashiro. 1990. The Formosan Subterranean termite in Hawaii. Res. Ext. Series 117. 4 pp.