Formosan Subterranean Termite

formosan subterranean termite

Formosan Subterranean Termite, Coptotermes formosanus


The Situation:  Apparently introduced more than 10 years ago from Hawaii, the destructive Formosan subterranean termite has taken a foothold in San Diego.  Native to mainland China, this species is established in 7 southeastern states and Hawaii.  It can develop huge colonies quickly and cause significant structural damage within 6 months.  This termite sometimes builds nests with no connection to soil, thereby making detection and control difficult.  Because there are no consistently good measures developed to control it, spread of Formosan subterranean termites could threaten homes over wide areas of California.

formosan subterranean termiteDamage:  A Formosan subterranean termite colony may contain more than a million individuals.  This termite commonly renders unprotected homes in Hawaii structurally unfit for habitation within 2 years, and condominiums in Florida have been damaged to such an extent that large parts of them need to be closed until control is obtained and repairs made.  This termite primarily lives underground, but attacks damp structural wood or wood to which it can bring moisture.  It encircles its nest with a hard adobe-like carton that sometimes causes walls or other voids in which it nests to bulge.  Damage may be undetected until it is significant.

Economic Impact:  Annual costs to control Formosan subterranean termites in Hawaii exceed $100 million and are about $60 million in Florida.  Cost for control at a home may be more than $5,000 because it often involves soil treatments and fumigation.  There may be additional costs for structural repairs.  Physical barriers such as special sand or wire mesh installed under buildings at the time of construction are used where Formosan subterranean termites are troublesome, but no such measures have yet been developed for California.  Such barriers are very expensive.

Distribution:  In California the Formosan subterranean termite is established only in La Mesa, an inland community near San Diego.  The termite is presently restricted to several properties within about a 1/4-mile radius, but flying reproductives have been caught nearly a half-mile away.  Colonies have been found in the ground around homes and in wood pots, structural wall voids and attics.  No specimens have been encountered in adjacent localities.

Research:  Strategies are being developed at the University of California, Riverside to eradicate or control this potentially destructive pest in San Diego, and to prevent it from causing damage to homes.  Extent of infestation and foraging range of individual colonies are being monitored with wood stakes in the ground and sticky traps under porch lights.  Areawide baiting with an insect growth regulator mixed into sawdust has shown great promise for eliminating the termite in a limited area.  Trials also are underway to find effective physical, behavioral or biological deterrents.  A community-based educational program was started to help homeowners become aware of this termite, the damage it causes, and best options for control.

Center for Invasive Species Research, University of California
CNAS-0143 (03/31/03)
Text provided by Michael K. Rust
Department of Entomology, University of California, Riverside
Photos courtesy of Gerald J. Lenhard, , Bugwood.org and Scott Bauer, USDA Agricultural Research Service, Bugwood.org

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