Mother Nature may yet be the best weapon in Orange County's war against red imported fire ants.
A study released Tuesday by the Orange County Fire Ant Authority supports the theory that Southern California's parched climate is too harsh for the venomous insects and that a lack of life-sustaining water has halted their spread to vast wilderness areas.
In a sampling conducted by the agency and the U.S. Geological Survey, experts examined thousands of ants collected in open areas such as Limestone Canyon, Orange Hills, Starr Ranch and Laguna Coast Wilderness Park. They found that none of the insects were red imported fire ants. Instead of colonizing these open areas, the ants appear to stick to heavily irrigated housing developments and golf courses, officials said.
Although infestations in the southeastern United States have proved to be particularly difficult to combat, the study suggests that California could fare better.
"This pretty much confirms what we've always thought," said Richard Bowen, program director for the Fire Ant Authority. "The climate is our biggest ally. The experts said we could probably eradicate them in three to five years, and I think those numbers are still good."
State agricultural officials said they too are encouraged by the report. "It's good news," said Larry Cooper, a spokesman for the California Department of Food and Agriculture. "We are still confident they can be eradicated."
The ants are native to South America and are believed to have spread across the United States in shipments of landscaping shrubs. Unlike most ants, this species delivers a venomous sting that produces immediate pain, burning and raised blisters.
The venom can be lethal to pets and sensitized humans. This summer a 2-year-old boy had to be taken to the hospital after he was stung by ants that had invaded his Ladera Ranch house.
Since the county began its $5.9-million eradication effort in February, workers have poisoned 2,983 infestation sites in 39 Orange County communities. Officials said the poisonings, which are intended to kill the queen of each ant colony, have an 88% success rate.
In this latest study, researchers placed 750 ant traps in wilderness areas and collected 18 species of ants, none of which were fire ants. Samples were collected and examined last winter, and spring samples are under examination now.
In addition to studying samples of ants in wilderness areas, the OCFAA also has appealed to residents and outdoor workers for help in reporting suspected fire ant colonies. Residents can report fire ants by calling (888) 4-FIRE ANT or by visiting the authority's Web site at www.ocfireant.com.