Can Termites Hitchhike North in Mulch From Gulf Hurricane Debris?

As spring gardening approaches, concern has spread about the risk of the Formosan subterranean termite (Coptotermes formosanus) moving to other states in mulch produced from Katrina and Rita debris. The termite wreaks millions of dollars of damage annually to wooden structures, live deciduous trees and other woody plants in a dozen southern states, including Louisiana. Barbara Thorne, professor of entomology and termite expert at the University of Maryland, comments on the situation.

The state of Louisiana imposed a quarantine in early October that prohibits movement of wood products and debris in order to prevent the spread of the Formosan termite. Nevertheless, people are understandably concerned because it is impossible to enforce this type of quarantine, despite the best of intentions.

Regarding mulch, termites do not have a very long half-life in a shredder, so fresh mulch is not a problem. Mulch that sits in one place for a period of weeks or months could become infested from termites underground, but based on reports from New Orleans and the Gulf coast, wood is being chipped and then moved out fairly quickly to make room for more.

Once mulch is bagged and stored at a distributor's or the destination property, termites residing in the soil may pierce the plastic bags and colonize the warm, moist wood chips within. It is not uncommon to find termites within bags of mulch, especially bags lying directly on the ground, but that scenario has been going on for decades and involves local termites.

A key thing to remember when mulching is to make the application as thin as possible, especially near a structure. Mulch creates a hospitable, warm, moist environment for termites to travel in or under, so to reduce the risk of structural infestation it is best to keep mulch away from buildings.

The higher risk for termite hitchhiking north from the hurricane zone is movement of construction debris, tree stumps, logs, etc. that might be infested with termites. Intact wood could readily transport termites. Movement of infested rail road ties has long been pegged as the primary mode of spread of the Formosan termite within the U.S.

06037