Did Termites Cause the Levee Breaks in New Orleans?

The Formosan subterranean termite, an insect from Asia, may have contributed to the levee breaks in New Orleans after Hurricane Katrina.
Photo: Scott Bauer, USDA Agricultural Research Service

The Formosan subterranean termite, native to China, has been chewing up levees in its Asian homeland since the 1950's. In the 1960's, populations of the invasive insects were discovered throughout the Gulf states in the U.S. Formosan termites can do some damage, as each colony may contain several million individuals foraging up to 300 feet in the soil. Could these exotic pests have caused the levee breaks that flooded New Orleans after Hurricane Katrina?

Yes, according to Gregg Henderson, a professor at the Louisiana State University AgCenter. In 2000, Henderson surveyed flood walls around New Orleans and found the structural seams were constructed from bagasse, a waste product from sugarcane processing. Bagasse attracts Formosan termites, and indeed, Henderson found evidence of termites in the seams at that time.

Five years later, post Katrina, Henderson and his colleague Alan Morgan inspected 100 seams, including those in flood walls with major breaches. At the 17th Street Canal, 27% of the inspected seams showed evidence of termite damage. At the London Street Canal, where two major breaks occurred in 2005, Henderson and Morgan found 70% of the seams had termite damage.

In addition to weakening the seams of these flood walls, Henderson asserts that Formosan termites may have tunneled through levees, leaving them susceptible to water infiltration and leading to possible collapse of the structures. Writing in the current issue of American Entomologist, Henderson warns that a complete survey of New Orleans' levees, as well as measures to treat them for termites, will be needed to prevent another disastrous flooding of the city.