Recent Stories about Formosan Subterranean Termites and Mulch

March 3, 2006
Michael Waldvogel, Extension Entomology

There has been a flurry of internet traffic related to an Oct. 2005 press release on Louisiana State University's website regarding the potential spread of Formosan subterranean termites (FST) in mulch being produced from infested trees in hurricane-affected areas in the state.

Louisiana's Dept.of Agr. & Forestry established a quarantine that requires all woody debris in the quarantined (hurricane-affected) areas to be shipped to an approved landfill within the designated quarantine area. Some of the material is being burned as fuel, but there are several state and federal agencies looking at this debris every day as it is deposited into these landfills. All contractors that are mulching and hauling the debris know the regulations and are abiding by them. LDAF has asked that anyone with knowledge of debris moving out of a quarantine area to contact their 24-hour hotline. More recently, the LDAF issued a follow-up press release to dispel the rumors flying about the internet.

So, essentially the internet story that many of you have seen and passed on (and passed on.... and passed on) is in my opinion a non-issue for us in North Carolina. I consider mulch to be a possible, but unlikely source of Formosan termites. Remember that termites live in a colony and just the physical disruption resulting from infested sections of trees passing through grinders/chippers is likely to disrupt that colony. If there is a threat, it would be from termites that inhabit the area where the mulch is piled moving up into the mulch and potentially nesting there. In that case, bulk shipment of the mulch would pose a risk. However, Louisiana's quarantine addresses that matter appropriately.

Wooden items such as pallets or railroad crossties either in use along existing rail lines or else removed and sold as landscape timbers potentially pose a more significant threat for introducing Formosan subterranean termites if these materials are brought in from known FST-infested areas. Although these crossties are creosote-treated for the most part, that does not appear to deter Formosan termites from entering them. Railroad ties being used as landscaping timbers were the source of our first FST incident in the early back in 1992 at Holden Beach (Brunswick Co.) and it appears that they are responsible at least in part for our current problem in Rutherford County in western NC. If you're not familiar with the situation out there, you can read about our program at the following site:

This doesn't mean that you should discontinue using railroad ties in landscaping if that is your preference. You just need to make sure that you purchase them from a reliable source and that you look them over carefully before buying them.

Regarding mulch in particularly, the best approach for homeowners and landscapers alike remains to keep ALL mulch from being piled against the foundation. ANY mulch will create moist conditions in the underlying soil and as such potentially attract termites. Even with inorganic mulches like gravel you can find termites beneath it because the soil moisture may be greater there than in surrounding open areas particularly during long stretches of dry weather (like we're having now). Depending on the type of mulch, the material may become food. A 6-12" wide band of gravel is probably a better choice for areas immediately adjacent to the foundation. Regardless of what mulch you use, termites in that mulch is not necessarily an indication that your house is infested with or needs to be treated for termites.

The first line of defense against termites is not worrying about your mulch. It's making sure that your house is not infested or susceptible to an infestation by virtue of having conditions conducive to termites in and around your home. You accomplish that goal through routine home maintenance and by having your house inspected by a pest management professional. Some suggestions on how to keep your home from becoming a "termite banquet" can be found at:

If you find termites in your mulch, collect as many as possible (preferably look for the soldiers which have distinctly darker heads) and bring them to your County Cooperative Extension Center and they will assist you in determining if these are Formosan subterranean termites or one of our native species.

The moral of the story is simple - as spring approaches, go spread your mulch, plant your flowers, and enjoy your gardens.

Some additional information about termites and protecting your homes against termites can be found at our website: