Formosa termite in mulch paranoia

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

Last year it was the 17-year cicadas, this year it seems we are going to have to deal with Formosan termite paranoia. Over the past week I have been besieged by a surprising number of questions about Formosan termites arriving in Michigan from mulch made from all downed trees in New Orleans and other hurricane stricken areas of the southeast. Since I have limited knowledge of Formosan termites, I spoke with Dr. Rudolph H. Scheffrahn, an entomologist and Formosan termite specialist with the University of Florida Fort Lauderdale Research and Education Center. According to Dr. Scheffrahn, the spread of Formosan termites via bagged mulch is very, very unlikely because of the following reasons.

1. Such an event would require the presence of a cohesive and viable Formosan termite colony, complete with reproductives, in the mulch upon its arrival to Michigan, not just a few termites in the bag. This is very unlikely because the process used to manufacture mulch would destroy any colony of termites present in a downed tree.

2. Colonies are very sensitive to exposure and disturbance. The very act of spreading the mulch in your yard will destroy any colony that moves into the mulch after it was manufactured by exposing the colony to predators and desiccation. The spread of the Formosan termite from New Orleans to Georgia is thought by many to have resulted from the transport of used railroad ties that contained large colonies of Formosan termites. Burying these ties in yards, as landscape timbers, would not have exposed the sensitive termites to predators and desiccation, which certainly would have helped their chances of survival.

3. The flight period of Formosan termite reproductives in the Southeast occurs between April and June, which was before the hurricane hit New Orleans and which has yet to happen this year, so any mulch produced after the hurricanes would not contain these colony-producing reproductives.

4. The temperature and moisture requirements of the Formosan termite fall within a very narrow range, which is why they occur almost exclusively in the Southeast United States. In the unlikely event that a viable colony did find its way to Michigan in a bag of mulch and it did survive being spread around in our yards, our winters are much too cold for the termite to survive here. Even along the Pacific Coast where environmental conditions are much more favorable to the termite, there is only a single, small neighborhood in San Diego where the termite is known to occur. Given all the commerce that moves from the southeast to Michigan, it seems to me that if the Formosan termite was capable of establishing in Michigan, it probably would have done so by now.

Fun fact: This rumor has grown to the point where it is now recognized as a bone fide urban legend by where the merits of this and other popular urban legends are discussed. Check it out

I’m thinking this is gonna be a nutty summer.

Additional information from Bert Cregg

The Louisiana Department of Agriculture and Forestry has issued a quarantine to further prevent the spread of the termite.  Wood and wood products cannot be moved from the hurricane-affected counties unless they are fumigated.  Lastly, if you want to avoid problems you can skip the bagged mulch at the big-box store, and go to your locally-owned landscape supplier for some Michigan-grown and Michigan-ground red pine bark mulch.

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