ORLANDO, Fla. — Inside a hapless fire ant, a tiny maggot is growing, feeding on the internal fluids and organs of the stinging insect. The maggot migrates to the ant's head, which soon falls off because of an enzyme released by the larval fly.
A metamorphosis takes place inside the head, and a smaller-than-flea-size phorid fly begins another generation by crawling out through the dead ant's mouth.
It's not science fiction or a horror movie. Scientists have released millions of the little decapitating flies along with other controls to put the bite on Florida's loathsome fire ants.
"It is not possible to eradicate fire ants in the United States short of sterilizing the whole South — and that would be pretty extreme," said Sanford Porter, lead scientist of the U.S. Department of Agriculture's Agricultural Research Service.
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"In South America, they are one-fifth to one-tenth the density here, and we think it's (because of) the natural enemies," he said of fire ants.
Came from South America
Fire ants came to the United States about 70 years ago from South America. Without natural enemies, they quickly spread throughout the South and are in 12 states and Puerto Rico, infesting more than 320 million acres. About 40 percent of the people in infested areas are stung each year, federal researchers say.
Fire ants fervently defend their nests from intruders, crawling on victims by the hundreds — sometimes thousands — when disturbed. In unison, thought to be triggered by a pheromone, each ant delivers burning stings over and over. A white pustule forms on the site of the sting, which will heal in 10 to 14 days. A protein in the sting can be fatal for people allergic to bee and wasp venom.
"Every year, ants cost $5 billion to $6 billion in losses, between medical treatment and damaging electronic equipment," said Phil Koehler, professor of entomology at the University of Florida in Gaines-ville. "They kill livestock and devastate the ecological environment, ground-nesting birds are destroyed, and sea turtles hatching out of eggs are killed."
Scientists, curious why there were fewer fire ants in their natural range, discovered the phorid fly along with other natural controls. The flies passed rigorous testing to ensure they would not cause problems for native plants and animals.
The first groups were released in 1997 around Gaines-ville and established themselves. Since then, phorid flies have been released in other locations, and each group expands its territory by 10 to 20-plus miles a year. The phorid implants one egg at a time into a fire ant's body.
"They won't attack other ant species; they're specific for fire ants," Koehler said.
The program to use biological controls is run by the Agricultural Research Service. The program's goal is to use baits and bio-controls to achieve a sustained 80 percent reduction of fire ants and save at least $4 billion in control costs and damages.
Local angle
● Arizona remains free of infestation by fire ants, says the state Department of Agriculture Web site.
As an example of the state's vigilance against the invader, the department says the state surveyed 265 high-risk sites such as nurseries, parks and truck stops in 2004, placed 48,636 bait traps and collected 6,963 ant samples. All samples were negative for the imported red fire ant.
The state has worked since at least 1999 to make sure the pest doesn't get established here.
From time to time, isolated incidents have been recorded in Arizona, however. Last year, some of the ants got a free ride on oak trees imported from a Texas nursery to landscape Marana Town Hall. The trees were quarantined and the ants were exterminated.
Fire ants infest more than 320 million acres in 12 Southeastern states and Puerto Rico, and have recently spread to California and New Mexico.
