Exotic insects find East Tennessee as ideal as the people who live here do. They're likely to keep coming.
by Joe Tarr
It seemed like an obvious question in researching fire ants: What does it feel like to be bitten by one?
"You can find out for yourself if you'd like. We've got some upstairs," responds Karen Vail, an entomologist with the University of Tennessee.
Upstairs is the lab where Vail—who has studied fire ants and their approach to Knox County—keeps, not one of those plastic ant farms, but a large Rubbermaid-style rectangular container filled with a fire ant colony. The insides of the container are painted with a white waxy substance to keep the ants from escaping. Inside, they scurry around as ants do. They don't look fearsome, just really small.
Vail's been bitten countless times; she hardly even feels it anymore. One crawls around her hand for a minute before deciding to chomp into her skin. "See, there he goes," she says.
"It's kind of a burning, fiery sensation. But nothing like a...wasp," Vail says of the effects. It's hardly lethal, but 1 percent of those bitten do go into anabolic shock, having trouble breathing. So she warns against trying it for research.
Accidentally imported in 1918 on plants brought from South America to Mobile, Ala., the fire ant has been slowly marching north ever since. Last fall, they were discovered in Knox County for the first time.
They're not the only invader. In a world where people and things move with increasing frequency and ease, bugs have been able to hitch rides. Some of them are brought to new lands where they have no predators and have an abundant food supply. Sometimes they can decimate the plant, insect or animal species they feed on. They can devastate crops or the landscape, or just become a huge pest.
Exotic or invasive species are causing species extinction worldwide. In East Tennessee, the hemlock wooly adelgids and fire ants are beginning their invasion, and gypsy moths will probably be here en masse in a decade or two. Other insect pillagers are sure to follow.
"We're going to continue to battle these situations," says Rusty Rhea, a forester with the U.S. Forest Service who is battling the hemlock wooly adelgid. Rhea wonders whether it makes more sense to practice better controls or just let every critter through. "We need to either open the floodgates or be more careful. I don't know what makes more sense. It's scary."
Getting Antsy
Last summer, Mary Wahl noticed the mounds all over her horse farm at Greenback in Loudon County. "They make a big mound and if you touch the mound, millions of these tiny red ants are crawling all over the ground," Wahl says. "And they sting."
Wahl had retired here from Michigan recently, but she wasn't the only one who found East Tennessee's conditions ideal. Loudon County Cooperative Extension agent John Goddard visited the farm to show Wahl how to control them. "She had about 65 mounds up and down her driveway and she's had a dickens of a time," Goddard says. It was the biggest infestation Goddard has seen in Loudon County. There will likely be bigger ones.
The fire ants are probably the most notorious invaders. Pulp novels and B-horror movies have been based on the creatures. There are actually three types of fire ants: black, red and a hybrid of the two. In the United States, their range is 320 million acres throughout the Southeast, Texas and some isolated parts of California and the Southwest. Their northern front is now in Tennessee, and the Carolinas.
Cold winters will eventually end their northern march, but scientists aren't sure exactly where that will be.
The ants can cause all kinds of problems. They get into tuberous crops; they can kill and blind calves. Farmers cut into the mounds when they harvest, damaging their equipment and sometimes getting covered with stinging ants in the process. "It's a terrible mess, besides the stinging and the biting," Goddard says.
In urban areas, the ants also break down gravestones in cemeteries. They can cause major damage to electrical equipment. Sometimes they get into houses.
"They feed on just about everything: live animals, dead animals, honey, nectar, oil from seeds," Vail says. They'll eat eggs of birds, snakes, and alligators. They're also extremely aggressive, battling and destroying native ant colonies.
And, of course, they sting. Fatalities are not common, but they have happened. Although one bite isn't that painful, Vail says, "The problem is it usually isn't just one ant, it's hundreds running up your leg."
The ants are also very prolific. A single-queen ant colony will have 100,000 to 240,000 worker ants. A multiple-queen colony (which has not been seen in Knox County) will have 100,000 to 500,000 workers. "The queen can lay 2,000 eggs in a day," Vail says. "They can out-compete any other arthropod, any other ant."
Humans inadvertently expand the ants' territory by moving them in dirt and plants. When dirt is excavated from an infested place and moved to another (say a future subdivision), the ants are carried along, to a place where they can thrive. "They like to nest in disturbed areas so urban areas create a lot of habitat for them," Vail says.
Fire ants aren't always immediately noticeable, and it can take a couple of years before their mounds build up so that they're seen. There are various ways of treating the ants, mostly through the use of pesticides. There are also some biological controls. A tiny phorid fly lays its eggs in the head of fire ants. When the eggs hatch, the ant dies. The flies also limit the ants' activity because they hide when the flies are out.
Too far from the flame
Another insect that could do significant damage to forests is the gypsy moth. Brought from Europe to Boston in the late 19th century, Gypsy moths have been slowly migrating south.
Gypsy moths don't kill the trees they feed on outright. But they defoliate the hardwoods in the spring, forcing the trees to grow new leaves and weakening them to other predators, diseases and droughts. And if the moths go unchecked for several years, they'll eventually kill the trees.
But the moths have been moving much slower than anticipated. "When I first started in the tree business back in the early '80s, they were predicting we'd have gypsy moths in 15 years," says Jim Cortese, owner of Cortese Tree Specialists.
The estimate for the Gypsy moth arrival is now 20 years, although it could be as little as five or 10, says Elizabeth Long, who monitors invading plant and insect species for the University of Tennessee. "With federal cutbacks and state cutbacks, there's always the possibility that these monitoring and eradication programs will get reduced," she says. "That might make it so they'll get here a little sooner."
There are some small outbreaks from time to time. They're often brought in on camping trailers from up north and set up in the Smokies. But the state and the U.S. Forest Service have an aggressive trapping program to keep them in check. They'll spray if a population gets too big. "It's becoming more of a problem but has not been established permanently," says Bruce Kauffman, forester and state forest health specialist. "We always get introductions into Sevier County through the camping mechanism, people bringing their RVs from the north. We have the traps there and try to capture them before they get established."
Sometimes the efforts to control exotic pests or nature go awry. Biocontrols were seen as a natural alternative to pesticides. But sometimes these controls have done more damage than the species they're supposed to keep in check.
The most famous example of this was introducing the mongoose to tropical islands to control rats in sugarcane fields. The mongoose fed on some rats, but they also ate just about every other small creature they could and had a particular craving for native birds.
In the United States, the European weevil was introduced to control an invasive thistle. The weevil worked, but then started feeding on the native thistles. Caterpillars released in the Caribbean in the '50s to rid ranchland of cacti found their way to the U.S. mainland.
The ladybug beetle being introduced to battle hemlock wooly adelgid appears safe because it apparently only feeds on adelgids. "Being that they're so small there's not much they can feed on," says Kristine Johnson, supervisory forester in the Great Smoky Mountains National Park.
But whatever tests scientists do before introducing a new species, they never know for certain what effect the little beasts will have.
There are sure to be more exotic insects invading East Tennessee. The problem isn't unique to the United States. We've shipped some of our insects off to other parts of the world, including the Eastern tent caterpillar, which has damaged trees in Europe.
"The main reason seems to be people are moving around a lot more. People are traveling more, bringing plants and soil and vegetables to areas we didn't use to," Long says. "I suppose it's feasible that things could get moved around so much they could live in a number of different places."
So keep the Deet handy.
March 6, 2003 * Vol. 13, No. 10
© 2003 Metro Pulse
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