Formosan Termites in Urban Trees, Vol. 7, No. 22
Formosan Termites in Urban Trees
That’s not a vine running up that tree. It’s a Formosan termite shelter tube. Although it is unusual to see one this long, it is not at all unusual to see trees infested with Formosan termites on the Mississippi Coast and in other areas of the state where these non-native termites are well-established. Formosan termites are known to occur in portions of 27 Mississippi counties, primarily in the southern part of the state.
The first step in dealing with termites in trees is to determine the species. If they are native, eastern subterranean termites, then there is really no problem. These termites only feed on dead or decaying wood and pose no real risk to the tree. The tree may well have a problem, but it is not a termite problem.
Formosan termites are a slightly different issue. Formosan termites will readily invade live trees, both at ground level and by aerial colonies higher up the tree. They may start by feeding on deadwood or heartwood, but Formosan termites will also eat live wood, which allows them to gradually hollow out cavities in infested trunks and limbs. Formosan termites do not usually kill trees by feeding in the cambium or causing similar damage, so they are not an immediate health threat to the trees they infest, but they can weaken trunks and limbs, increasing the potential for windfall or breakage. Formosan termites are not particular about the kinds of trees they attack. Oaks, pines, maple and other hardwoods, palms and even cypress are all susceptible.
What to do if you find Formosan termites in a tree or trees in your yard? First, check to be sure your house is properly protected from termites. When was the house treated last? When was it last inspected? Do you have an active termite contract? If you live in an area where there are Formosan termites in landscape trees, don’t worry about the trees until you are sure the house is protected!
Once you get back to thinking about the trees, the first step is to check for termites and do a value and hazard assessment. If there are many trees in the landscape, it may not be practical to treat or protect them all. Some trees are priceless; some trees are liabilities. Consider the trees that are most important to you, trees that add lasting value to the home and landscape, or trees that present special hazards if they are weakened by termites. Then focus your treatment and protection efforts on these trees.
Control: The tools and methods used to treat trees for termites are similar to those used on buildings. Liquid termiticides can be injected into infested voids and applied to the root flare perimeter. Termite baiting stations and/or above-ground bait stations can also be used. To assure effective, lasting protection, such treatments are best applied by a structural pest control company or a licensed horticultural pest control company. But not all companies are equally as familiar with or comfortable with treating trees for termites, so take time to get bids and information from several companies.
See Extension Publication 2568, Protect Your House from Termites for information on termite control in buildings. Also see the MSU Extension Termite Website for more information on termite identification and biology—including information on how to identify Formosan termites.
Blake Layton, Extension Entomology Specialist, Mississippi State University Extension Service.
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