Fire Ants Continue to Spread
Currently there are 16 "fire ants" states that are particularly at risk. They are: North Carolina, South Carolina, Georgia, Alabama, Arkansas, Mississippi, Texas, Florida, Louisiana, Tennessee, New Mexico, Oklahoma, California, West Virginia, Virginia, and Arizona. Are you at risk? Let us know!
While there are several species of fire ants found in different parts of the United States, one species, the red imported fire ant, has become a particularly pressing problem around much of the country, causing billions of dollars in damage each year. They now infest 16 states, heavily concentrated in the southeast, but reaching as far west as California and as far north as Delaware.
Red imported fire ants are an alien species of ant, meaning they are not native to U.S. soil. They were accidentally introduced into the United States in the 1930s when they arrived in a shipment from South America. They first became established in the area around Mobile, Ala. These immigrants found few natural enemies in the United States, which allowed them to spread quickly, frequently displacing many native ant species along the way.
Through their natural reproductive process, fire ants can generally spread at a rate of five to 12 miles per year. However, this natural process is not the only means fire ants have of spreading across the country. Much as they arrived in the country as stowaways, groups of fire ants or even entire colonies can hitchhike in shipments of gravel, sand, soil, crops or other products. These free rides contribute to the ants spreading faster and further, and have led to quarantines and restrictions on transporting certain products across many parts of the country.
Floods also have been known to displace fire ant populations, dispersing them at an accelerated rate as entire colonies float down a river or stream. Fish have actually turned up dead with bellies full of fire ants after periods of frequent flooding.
“Depending on weather conditions and a number of other factors, the natural spread of fire ants is usually no more than a few miles a year, 12 to 15 at the very most,” says Dr. Charles Barr, an extension program specialist for the Texas Cooperative Extension. “Anything beyond that is usually the result of human activity.”
For example, the presence of fire ants in Delaware, a significant distance north of their natural range, surprised a number of people. Sure enough, the infestation, discovered in a landscaped portion of a townhouse development; was thought to have come from a shipment of azaleas from further south. With all the new territory fire ants have claimed on their own, they certainly don’t need any human assistance.
This entry was taken from the March 2005 issue of Managing Fire Ants, available at GardenTech's Web site.
