Quick answer: The Formosan subterranean termite — the most destructive insect in Louisiana — hollows out the structural wood of New Orleans homes: sill plates, floor joists, subflooring, and framing. A licensed pest professional must eliminate the colony first; then the damaged structure is rebuilt. Repair is a separate job from extermination.
New Orleans sits at the center of the worst termite problem in the United States. The Formosan subterranean termite — the species behind that damage — hollows out the structural wood of New Orleans homes: sill plates, floor joists, subflooring, and framing. This guide explains why Formosan termites are so destructive here, how deep the problem runs across the metro, and why the damage they leave behind requires structural repair, not just extermination.
What is the Formosan subterranean termite?
The Formosan subterranean termite (Coptotermes formosanus) is the most destructive insect in Louisiana. Native to East Asia, the Formosan subterranean termite arrived in the United States after World War II and was established in New Orleans by 1966. Unlike the native subterranean termite, the Formosan subterranean termite builds enormous colonies and, as long as it reaches moisture, can sustain nests above ground inside a building rather than depending on soil contact. That combination — huge numbers and the ability to live inside the structure — is what makes the Formosan subterranean termite the defining threat to New Orleans homes.
Why is termite damage worse in New Orleans than almost anywhere else?
Termite damage is worse in New Orleans because of scale. The LSU AgCenter estimates the Formosan subterranean termite causes about $300 million in property damage every year in New Orleans alone, and more than $500 million per year across Louisiana. The reason is a numbers game: a native Louisiana subterranean colony holds up to about 1 million individuals, while a single Formosan colony holds up to 10 million — and one colony recorded in Algiers, Louisiana held an estimated 70 million. A colony that large consumes structural wood far faster than a native colony, and New Orleans’s dense stock of older wood-frame homes gives it an enormous food supply. The LSU AgCenter has called the Formosan subterranean termite one of the most formidable pests ever to invade Louisiana.
How did Formosan termites reach New Orleans?
Formosan termites reached New Orleans through the port. The Formosan subterranean termite is native to East Asia and was carried to U.S. port cities in infested wooden material after World War II. LSU AgCenter entomologists first identified the Formosan subterranean termite in Louisiana in 1966, and the species was established in New Orleans by that year. New Orleans has therefore lived with Formosan termites for more than half a century — long enough that the damage is not a new or occasional event but a permanent condition of owning a wood-frame home in the metro.
What is Operation Full Stop, and did it eliminate the termites?
Operation Full Stop was a federally funded, area-wide program that treated entire blocks of the French Quarter for Formosan termites from 1998 to 2012. The United States Department of Agriculture funded the treatments, and the LSU AgCenter set the program’s parameters. Operation Full Stop reduced the Formosan population in the treated area — but Operation Full Stop did not eliminate the colonies. A 2025 follow-up study in the Journal of Economic Entomology found that, more than a decade after the program wound down, Formosan colonies still swarm across the French Quarter and roughly half of its structures still carry termite bait. The lesson for homeowners is direct: even the most intensive control program on record only suppressed these termites, so any New Orleans home remains exposed and any damage already done still has to be repaired.
Which New Orleans parishes are under the Formosan termite quarantine?
The Louisiana commissioner of agriculture imposed a Formosan subterranean termite quarantine on October 3, 2005. The quarantine covers 12 parishes, and every core metro parish sits inside it: Calcasieu, Cameron, Jefferson, Jefferson Davis, Orleans, Plaquemines, St. Bernard, St. Charles, St. John the Baptist, St. Tammany, Tangipahoa, and Washington. Orleans and Jefferson — where New Orleans, Metairie, Kenner, Harahan, Gretna, and Marrero all sit — are both quarantined parishes. The quarantine restricts moving termite-prone material out of these parishes, and its footprint is a plain measure of how established the Formosan subterranean termite is across Greater New Orleans.
When do Formosan termites swarm in New Orleans?
Formosan termites swarm in New Orleans from April through June, with the peak in early-to-mid May. Louisiana homeowners commonly see the first major swarm around Mother’s Day, though earlier swarms are not unusual. During a swarm, winged Formosan termites (alates) leave the colony, drop their wings, and pair off to start new nests — which is why swarm season is when many homeowners first discover an infestation, often after the structural damage is already underway. Swarm season is a warning to inspect, not a starting gun; by the time alates appear, an established colony has usually been feeding for a while.
What structural damage do Formosan termites cause in New Orleans homes?
Formosan termites attack a New Orleans home from the ground up. The Formosan subterranean termite reaches the lowest wood first — the sill plate resting on the foundation, the rim and floor joists, the base of wall studs, and the subfloor — then works upward through the framing. Because these are load-bearing members, Formosan damage is structural, not cosmetic: a hollowed sill plate or joist weakens the frame that holds the house up. New Orleans’s many raised and pier-foundation homes expose those low structural members directly to soil-borne colonies, which is why sill-plate and floor-joist damage is the repair these homes most often need.
Why does Formosan damage require structural repair, not just extermination?
Formosan damage requires repair because extermination does not restore wood. Killing the colony stops the feeding; it does not rebuild a hollowed sill plate, sister a weakened joist, or replace a compromised subfloor. Those are carpentry and structural jobs. New Orleans termite damage repair is the second step, performed after a licensed pest professional confirms the colony is eliminated — repairing occupied wood only lets the termites return to the new lumber. So a New Orleans homeowner facing Formosan damage needs two different services in order: a pest professional to treat the colony, and a repair contractor to restore the structure the colony destroyed. See how termite damage repair works for the repair sequence.
Sources
- LSU AgCenter — Formosan Subterranean Termites in Louisiana (Smith, Ring, Henderson, Wu, Dunn): $300M New Orleans estimate; colony sizes (1M / 10M / 70M Algiers); identified in Louisiana 1966. https://www.lsuagcenter.com/portals/communications/publications/agmag/archive/2001/spring/formosan-subterranean-termites-in-louisiana
- LSU AgCenter — Formosan Subterranean Termites (topic page): Oct 3, 2005 quarantine + 12 parishes; “most destructive insect in Louisiana.” https://www.lsuagcenter.com/topics/environment/insects/termites/formosan_termites
- LSU AgCenter — Integrated Pest Management of Termites… A Louisiana Perspective: $300M New Orleans / $500M Louisiana annual loss estimates. https://www.lsuagcenter.com/topics/environment/insects/termites/integrated-pest-management-of-termites-and-other-wood-attacking-organisms—a-louisiana-perspective
- LSU AgCenter — Preparing for the Termite Swarms (Sun): swarm season April–June, peak early-to-mid May, around Mother’s Day. https://www.lsuagcenter.com/profiles/qsun/articles/page1620966062329
- Cottone, Janowiecki, Su & Riegel (2025). “The impact of Operation Full Stop… 10 years later.” Journal of Economic Entomology 118(3):1023–1028. https://doi.org/10.1093/jee/toae297