I wrote about Tawny Crazy Ants in January.
The relatively mild winter coupled with an extraordinarily wet spring and summer have produced an accelerated spread of colonies of these ants along the Coast. As a result, I’ve received calls and letters from concerned members of the public as these ants begin to invade their homes. So, I decided to reprint my column.
Tawny crazy ant colonies can grow to gigantic sizes with populations of workers in the millions and over 100 queens per colony. They don't nest underground or build mounds like most ants. So their nesting sites are somewhat inconspicuous. Instead, they find a convenient spot under a bale of hay, beneath the bark of a tree, under a board or flower pot, in cracks and crevices, in wall voids or inside houses or other buildings.
Once established, the ants dominate the environment. They wipe out virtually all insect life within their area, good or bad. The exception are bugs like scales, mealy bugs and aphids from whom they collect sugary honeydew. Sugars from these insects, along with plant exudates from nectaries, make up their major food sources.
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This depopulation can have a devastating effect on non-insect species by eliminating a food resource. They also harm vertebrates by attacking eyes and nasal passages. Researchers in Texas have documented these ants clogging the airways of domestic chickens causing suffocation.
The good news is that they kill imported fire ants. In Texas, they use the lack of fire ant mounds as an indicator for the presence of tawny crazy ants. However, that may not be as good a thing as you might think. In a survey conducted a few years back, most residents of Sugarland TX preferred to have the fire ants. That alone should give you some idea how bad these ants can get.
TCA’s most damaging characteristic is their love of electricity. TCA's have been documented destroying computers, power transformers, alarms, telephone exchanges, electrical meters and even sewage pump stations. The Johnson Space Center has hired professional pest control operators strictly to keep the ants under control and away from their multimillion dollar super computers.
TCAs have managed to infest two of our major research centers here on the Coast: NASA’s Stennis Center in Hancock County and the Gulf Coast Research Lab in Jackson County. They’re also on Keesler Air Force Base. At each site, they threaten the computers and other expensive electrical systems and become a significant concern for the personnel and administrators.
Traditional controls for ants haven't proved successful. There has been a special exemption given to our part of the state where TCA have been found for the application by professionals of a pesticide containing the active ingredient fipronil. Some baits have shown limited success in controlling TCA. Since this is a tropical ant, its numbers can decrease significantly during the colder months.
You should begin setting out baits in the late winter or early spring, as soon as the ants are active. Even the overwintering colony can be quite large. Multiple applications will be necessary throughout the spring.
Another thing to consider: reducing their food sources. An application of products containing imidacloprid or dinotefuran to your shrubs and trees will significantly lower the numbers of aphids, whiteflies and scales which supply TCA with nutrition.
Among the contact insecticides currently available to you gives only temporary control, two to three months. Synthetic pyrethroids such as bifinthrin, cypermethrin, cyfluthrin, deltamethrin, lambda-cyhalothrin, permethrin and s-fenvalerate can be used to establish buffer zones around your house.
Unfortunately, these over the counter treatments may only have a temporary effect. We simply don't have sufficient data to know one way or the other. If you think you have these invasive ants at your home or place of business, your best bet is to contact a professional. The sooner the better.
I've no doubt that in the next few years this ant will become a dominant species in South Mississippi. Meaning: if you don't have them now, you will get them sooner or later.
Tim Lockley, a specialist in entomology, is retired from a 30-year career as a research scientist for the U.S. Department of Agriculture. For answers to individual questions, please send a stamped, self-addressed envelope to Tim Lockley, c/o Sun Herald, P.O. Box 4567, Biloxi MS 39535.