Ernst: Fire ant has become our unwelcome visitor

By Eric Ernst

Published: Wednesday, December 15, 2010 at 1:00 a.m. Last Modified: Tuesday, December 14, 2010 at 10:08 p.m.

Years ago, on my parents' first visit to our new home in Florida, my father decided to mow the lawn while I was at work.

He hadn't brought his work shoes, so he undertook the mowing barefooted, quickly encountering another immigrant to Florida, the fire ant.

By the time I got home, my father's lower legs were covered in pustules. “I guess I'm not in Ohio anymore,” he said.

He was lucky. If he had been allergic – and an estimated 500,000 people in the Southeast are – “one sting would send you to the hospital,” says entomologist Fred Santana.

Fire ants are a popular topic for the insect lectures Santana offers regularly through the Sarasota County Cooperative Extension Service.

Of the 220-some species of ants found in Florida, fire ants are the No. 1 pest to humans, livestock and wildlife, he told an audience last week.

A fire ant nest can have single or multiple queens and 200,000 to 500,000 inhabitants, most seeming to take immediate offense when something disturbs them.

They attack cattle, ground-nesting birds and soybean crops. They can even disrupt harvests when they forage in fruit trees and swarm over pickers. They don't decimate crops, but they can lower the yields.

Carried by ships from South America in the early 1900s, they've overrun native species and infested 14 southern states. Nests also have been found as far north as Philadelphia, where microclimates have allowed them to survive the cold.

It looks as if they're here to stay, considering the natural predators that keep them in check in their native lands do not live here.

The University of Florida has raised and released phorid flies, whose larvae decapitate fire ants. Santana, who has introduced the flies at several locations in Sarasota, says they do their job, but simply don't have the numbers to eradicate the ants. At best, they may have dampened the ant populations in the test areas, he says.

For those of us who don't have phorid flies handy, Santana recommends baits, such as Amdro (active ingredient hydramethylon) and Once & Done (active ingredient indoxacarb).

Once & Done works within about three days, while Amdro takes as long as two weeks. Santana says he likes the slow-acting baits. They provide time for all the insects in the nest to ingest them. Otherwise, the chemicals might reach only the foragers.

Storage is also important, he says. The baits don't last long in the heat of the garage or when exposed to moisture. He recommends placing a plastic bag between the lid and the container to act as a seal.

As a nest treatment boiling water works to an extent. It kills some ants, but probably not all. It also kills any vegetation it touches.

For an offbeat treatment, Walter Reeves of the University of Georgia agriculture department swears by two cups of club soda poured directly in the center of a mound. The carbon dioxide in the drink is heavier than air and replaces the oxygen. Santana says he'd have to see some research before he buys into that approach.

Relief from stings comes in many forms. Take your pick from: bleach; Listerine antiseptic mouthwash, juice from an aloe plant; lip balm; papaya flesh; meat tenderizer and vinegar.

Better yet: Watch where you step.