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Horticulture and Home Pest News
Horticulture & Home Pest News is filled with articles on current horticulture, plant care, pest management, and common household pests written by Iowa State University Extension specialists in the Departments of Entomology, Horticulture and Plant Pathology.

Termites in Mulch - Another Urban Myth

This article was published originally on //

There has been considerable interest in Formosan termites after an article began circulating on the Internet claiming Formosan termites will be coming to eat your house if you buy low priced wood-chip mulch from garden centers this spring. The theory is that trees blown down in New Orleans by Hurricane Katrina were infested with termites and that those trees willed be chipped into mulch and shipped across the country, spreading Formosan termites.

In my opinion, this scenario starts with a small ounce of fact, but then adds sensationalism and exaggeration while ignoring other pertinent facts to come up with an urban legend.

Yes, there are Formosan termites in New Orleans and yes, they create aerial colonies (above ground) in trees, especially in the rainy, humid environment of New Orleans. Yes, they are extremely destructive to houses and difficult to control. See http://www.agctr.lsu.edu/termites/.

Yes, there are warnings and quarantines against moving building materials from damaged homes for use in other structures or areas. Of special concern are architectural components such as beams, doors and salvaged lumber and lumber taken from damaged buildings and stored on the ground where it can become termite-infested. Railroad ties and landscape timbers installed on the ground are similarly a potential problem, and have a far greater and better documented risk of moving termites.

The state of Louisiana neither encourages nor condones the sale of wood waste in mulch from the hurricane damaged areas. If anyone is chipping, bagging and selling mulch from southern LA, it is being done under the radar and illegally. The same would be true for Texas where there are also large quantities of wood from Hurricane Rita-affected areas that also have Formosan termites. It is very unlikely that any retailer, especially large retailers mentioned in the Internet article, would buy and distribute mulch from illegal sources.

We do not know for sure that termites will not survive in wood chips, but we believe that it is highly unlikely that they would survive the mulching/chipping process. The chipping process is as destructive to insects as it is to tree limbs and the likelihood is low of transporting a viable colony of Formosan termites in this manner. Further, any composting that occurs will raise the temperature inside a mulch pile to the point that termites will not survive.

In summary, there is no guarantee Formosan termites will not spread, but the claims made in the current Internet rumor are overblown and needlessly alarmist for those of us living in the upper Midwest, far away from the normal range where Formosan termites can survive.

If you do suspect an insect infestation in bagged mulch, you can use a garden insecticide as you would for control of ant mounds or other soil insects. You could also reseal any bagged mulch suspected of harboring insects and place it in a larger black plastic garbage bag and put it in the hot sun for several days. Raising mulch temperatures to 120 degrees Fahrenheit for an hour or more is generally sufficient to kill all insect life.

Finally, another way to ensure that you don't introduce unwanted termites into your landscape is to purchase garden mulch from a reliable, local source. Many municipalities now produce and sell mulches produced from city yard trimmings and landscape waste. This should be a safe source for mulch and is a great way to close the circle and encourage recycling of a local, valuable resource.

Page References: 
17
Year of Publication: 
2006
Issue: 
IC-495 (4) -- March 8, 2006