Garden Talk

with Rebecca Jordi


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Q: Formosan termites have been in the news lately – what can you tell me about them?

 

Formosan subterranean termite

Formosan subterranean termite

A:  The Formosan subterranean termite, Coptotermes formosanus, is the most widely distributed and most economically important of the termite species. The Formosan subterranean termite (FST) acquired its name because it was first described in Taiwan in the early 1900s, but Coptotermes formosanus is probably endemic to southern China. This destructive species was apparently transported to Japan prior to the 1600s and to Hawaii in the late 1800s.  By the 1950s, it was reported in South Africa. During the 1960s, it was found in Texas, Louisiana, and South Carolina. In 1980, a well-established colony was thriving in a condominium in Hallandale, Florida. Just recently, they have been identified in Duval County. A single colony of FST may contain several million termites (versus several hundred thousand termites for native subterranean termite species) which can forage up to 300 feet in soil. Because of its population size and foraging range, the presence of FST colonies poses serious threats to nearby structures. The scariest part – once established, FST has never been eradicated from an area. There are more soldiers (10 to 15%) in an FST colony than the native subterranean species in Florida which generally contain only 1 to 2% of the total colony. Because the FST colony contains a larger soldier proportion than native subterranean termites, infestations with many soldiers is a clue to its presence. The FST attacks structural lumbers and living plants because they are sources of cellulose. However, this termite is also known to attack non-cellulose materials such as plaster, plastic, asphalt, and thin sheets of soft metal (lead or copper) in search of food and moisture. Their highly publicized ability to penetrate solid concrete is a fallacy. However, the FST is persistent in finding small cracks in concrete, which they enlarge and use as foraging routes. Leaky plumbing, air conditioning condensate, and any portion of the building collecting excessive amounts of moisture should be corrected to maintain an environment less attractive to FST. The conventional method for control of subterranean termites, including the FST is to place a chemical barrier between termites and the structure to be protected. In recent years, baits have become available to control Formosan subterranean termite populations near a structure. When termites are found in the station, the monitoring device is replaced with a tube containing chitin synthesis inhibitor (CSI) laced bait with the active ingredient hexaflumuron. Termites feeding in the stations then carry baits to other members of a colony, leading to the demise of entire colony population.  For more complete information, please read the following University of Florida publication:  http://edis.ifas.ufl.edu/in278

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