If you've ever been stung by a red imported fire ant (RIFA) you won't soon forget it. Actually, it's uncommon to be stung by a single fire ant. You're more likely to be attacked by many or several fire ants if you're unwary and unfortunate enough to disturb a nest and stick around long enough for them to mobilize and attack.
PHOTO BY USDA APHIS PPQ.BUGWOOD.ORG.
That was my experience on a roadside just outside of Beaumont, Texas, a few years ago. After stopping my car to photograph the famous Spindletop oil rig, the site of the largest gusher in the world when it erupted in January 1901, I stepped onto a sandy patch of grass and, unthinkingly, scuffed up a fire ant mound. Up my right pant leg they went and a lively jig I did.
The RIFA (solenopsis invicta) is not native to the United States. It came unannounced and unwanted. It's believed that these aggressive invaders arrived sometime in the 1930s on a ship docked in the port of Mobile, Ala. Now that they're here, they're here to stay, despite the hundreds of millions of dollars spent by the U.S. government trying to eradicate them. In fact, their range is slowly expanding and may continue to spread until they encounter regions too cold or too dry for them to survive from season to season. The recent warming trend in the United States may aid their dispersal, in fact. But, that's conjecture at this point. As of 2011, they could be found over an area of 320 million acres, in a poorly defined swath stretching from Maryland up to Oregon.
These aggressive critters are reddish brown to black and they usually build dome-shaped nests. In sandier soils the nests aren't so prominent, as I discovered to my misfortune. The University of Florida IFAS Extension says that there are two types of RIFA colonies: single-queen and multiple-queen. The singe-queen colonies have just one egg-laying queen and may contain as many as 100,000 to 240,000 workers. Multiple-queen colonies have many egg-laying queens and may have as many as 500,000 workers. The sheer number of fire ants on some properties near humans or livestock is reason enough for concern.
Their propensity to fashion their nests near electrical equipment and utility housings, sometimes causing short circuits and fires, and the painful stings they inflict on livestock and humans qualify them as pests to be taken seriously. The venom in their painful, burning stings often cause pustules and intense itching that may persist for days on victims. A percentage of sting victims suffer severe allergic reactions.
Many products on the market are labeled to control RIFA. Dozens of products are sold to kill or manage them, including several in big box stores and hardware companies for homeowner use. Licensed pest control and turfgrass professionals are best trained to manage RIFA on residential, school and public properties in regions where they're common. Professional, licensed applicators should know which products work best for specific situations and are trained to use products according to label directions.
In most soils red imported fire ants will build a nest that looks like a gopher mound. The mounds aren't so noticable in very sandy soils.
PHOTOS COURTESY OF USDA APHIS PPQ ARCHIVE, USDA APHIS PPQ, BUGWOOD.ORG, UNLESS OTHERWISE NOTED.
Many application companies market their RIFA services to property owners and property managers as part of their overall lawn fertilization/weed control/pest treatment package, and some as a separate add-on service. Many homeowners value the service as much for the promise of ridding their yards of unsightly mounds as for the likelihood of being stung. Obviously, a large presence of RIFA can't be tolerated in areas where children and/or pets play regularly, such as schools, day care centers, sports fields and parks.
Identify your enemy
The keys to managing RIFA are similar to those for managing any turf or ornamental pest and starts with an accurate identification of the pest. Almost every region of the United States has many varieties of ants and some areas have several varieties of fire ants, including native species that are not as aggressive and not viewed as pests. The two pest species are the RIFA and the black imported fire ant. The black imported fire any is found primarily in Alabama and sections of Mississippi. The RIFA is the bigger problem of the two.
With apologies to Jeff Foxworthy, you know you're a RIFA if:
1. You build mounds of loose soil above ground and they look like gopher holes.
2. Your mounds are generally numerous and conspicuous.
3. You're a dark-colored worker ant, and all you need is for someone or something to disturb your digs to cause you to attack and sting relentlessly. You can be of varying size, up to about one-fifth an inch.
4. You have the same body proportions with your head width never exceeding your abdomen width, even if you're one of the biggest workers in your nest. (Thanks to Larry Gilbert, director, Brackenridge Field Laboratory, The University of Texas at Austin for the information.)
Following an accurate identification, it's time to determine the best management option. This will depend upon the size of the property and the severity of the infestation. It may not be possible to eliminate all the RIFA from very large areas due to excessive cost or other considerations, such as infestations in adjoining areas.
In recent years, companies such as DuPont Professional Products, Bayer Environmental Science, FMC and others have instituted well-thought-out programs to help professional application companies solve RIFA problems for their clients. They and other industry suppliers offer a range of products from baits that offer extended control to individual mound treatments, combo bait and mound treatments, barrier and spot-treatments.
A broadcast bait application eliminates the need to locate mounds because it relies on foraging fire ants to find and feed the baits to the rest of the colony. Because you're not treating individual mounds, you can treat larger areas in less time. For baits to be effective, use fresh bait, keep baits dry and apply baits when fire ants are actively foraging. Workers will forage for food, day and night, more than 100 feet from their nests. They're most active when air temperatures are between 70 and 90 degrees Fahrenheit. Watch to see if RIFA start removing the baits within 10 to 30 minutes. If they're actively foraging you will see this.
Areas with excessively high populations of RIFA mounds may require two applications of bait within several months to provide satisfactory management. And even if you're successful for a season, new queens may return in the future and re-infest the property.
In treating individual mounds, your goal is to kill the queen, or, in the case of mounds with multiple queens, all of them. That will eliminate the colony. If you don't destroy the queens they will continue laying eggs. There are lots of ways, chemical and non-chemical, to eliminate an individual mounded nest. But be aware that if you don't do a thorough job of it, your individual mound treatments may cause the surviving ants to pack up and create a new mound elsewhere.
The decision of whether to use baits (and some are used as mound treatments), drenches, granules, dusts, aerosols or other techniques rests upon the size and types of properties you're treating, your company's customer marketing and service strategies, environmental and safety considerations, and, ultimately, upon your customers' expectations.
Even after factoring all of these variables into your program, you may want to check with your regional or state extension expert. They usually have the most up-do-date information on RIFA and what's working best to control the pests.
Ron Hall is editor-in-chief of Turf magazine. He has been reporting on service industries, including the landscape/lawn service industry, for the past 28 years. Contact him at firstname.lastname@example.org.