Termites were in the news this week. Widely disseminated emails cautioned against buying mulch because it might be infested with the dreaded Formosan termite. The Formosan termite arrived in the gulf region in the mid – 1960’s from Asia and has become the bug that ate the south. It causes more than a billion dollars of damage to homes and structures each year from Florida to Texas. Last year hurricanes Katrina and Rita provided millions of tons of fresh food for Formosan termites in the form of trees, shrubs, and damaged structures ripe for setting up termite homes. Recent messages on the internet suggest that wood infested with Formosan termites had been processed into mulch and widely distributed around the United States. While the spread of Formosan termites in wood products is possible, it is too early too tell if this will be a problem at all.
Preventing the spread of termites
Several factors should reduce the chances of Formosan termites invading the north. First, Louisiana imposed quarantine on the movement of wood and wood products from the areas affected by the hurricanes. Damaged trees and lumber from homes and structures are being processed and deposited in designated landfills within the quarantined area. Communications from the state of Louisiana indicate that local contractors understand and adhere to the quarantine. Second, the mulching process is largely incompatible with termite life. Wood may be chipped or shredded to make mulch. This is tough on termites. Termite colonies have a better chance of remaining intact and surviving when larger pieces of wood are moved. Formosan termites are known to move in large wood products such as partially decayed railroad ties. The recycling of railroad ties is thought to be part of the reason that Formosans are so widely distributed among the southern states. Another factor that makes establishment of Formosans in our area unlikely is their inability to survive the winter outdoors. Formosans are fair weather termites unlikely to withstand the cold winters much further north than Tennessee. One sure way to reduce any chances of bringing this invader home is to purchase your mulch locally. Many municipalities sell mulch in bulk that has been produced locally. I have spoken with owners of retail nurseries in our area and they assured me mulch sold in their stores is produced in Maryland and nearby states such as Pennsylvania, West Virginia, Virginia, and New Jersey. The odds of Formosan termites arriving at your home in contaminated mulch appear low to me. Does this mean you will not find termites in a bag of mulch? Absolutely, not!
Eastern subterranean termites foraging on a piece of wood. Notice the soldier in the center of the picture with the huge head and large, powerful jaws surrounded by worker termites.
In my back yard, four unused bags of mulch lie on the ground next to a tool shed. There is a fair chance that when I open one of these bags it will be infested with a colony of eastern subterranean termites. I have a rotting locust stump with a large termite colony not 30 feet from these bags. Perhaps, one of the foraging routes of these termites runs beneath these bags of mulch. The jaws of the termites are powerful enough to gnaw a hole in plastic bag. Once a breech has been made, a bag of mulch can become a haven for termites. Later this spring when I am ready to spread the mulch I might be greeted with a termite jamboree.
Avoiding termites
Bags of mulch in contact with the soil may be colonized by termites.
How can you avoid termites in your mulch bag? Store unused bags off the ground. Termites are most likely to get into bags or wood in general if there is direct contact with the soil. What should you do if you open a bag of mulch and find it infested with termites? If this bag has been sitting around your yard since last year or longer, you can bet that the termites are locals and probably originated in your yard. One savvy gardener suggested the following course of action. Place your infested bag of mulch in a large black plastic bag, seal it up, and place the bag in an exposed spot such as patio or driveway and let this cook in the sun for a few days. Temperatures above 120 0 F are lethal to many kinds of insects and stand a good chance of roasting these little devils. This is certainly worth a try and for any insect gourmands the notion of sun roasted termites might be awfully enticing, yum. If you purchase a bag of mulch and discover termites within, return it to the seller. Suppliers that I have spoken with said they would gladly replace termite infested bags of mulch purchased at their store. To reduce problems with eastern subterranean termites in your landscape beds keep your mulch layer relatively thin about 2 inches. This will allow the mulch to dry out periodically. Termites need a wet environment to survive and thrive. Also, a mulch free zone of about 12 – 18 -inches around the perimeter of your foundation may create a barrier that prevents termites in your landscape beds from reaching your home. Termites are ubiquitous in our landscapes but with a little diligence you can keep the enemy beneath, the enemy outside your home.
References
Special thanks to Dr. Barbara Thorne for information on termites and for supplying the gorgeous subjects photographed in this Bug of the Week.
To learn more about the biology and management of Formosan and eastern subterranean termites, please visit the following websites:
http://www.agnr.umd.edu/MCE/Publications/PDFs/EB245.pdf
http://www.lsuagcenter.com/en/environment/insects/Termites/