Did you know that fire ants were not always found in the Southeast?
They are originally from a relatively small area in Argentina. About a century ago, they made it to the southern United States most likely as stowaways on boats. Now ants have migrated into 11 southern states, and are in 71 of the 100 counties in North Carolina.
Why are they such a problem?
The main reason fire ants are such a problem is because they form large, aggressive colonies. Most people are familiar with fire ants because of the large mounds they create as well as the painful sting they inflict. Stings from fire ants can cause a painful, burning itching sensation, which can last for up to an hour. Within about 24 hours a raised white pustule forms at the site, and persists for many days. Although the stings are not usually life threatening they can easily become infected and leave a permanent scar.
Why are they so hard to control?
It is impossible to eradicate fire ants. They reproduce quickly and can re-invade an area readily. Unlike many insect pests, fire ants are very organized, with each ant having its own role to play in the success of the colony. Most abundant are the worker ants, whose job it is to protect and feed the queen as well as defend the nest from intruders.
In the fall, you may encounter winged ants taking part in a mating flight. These flights usually occur in the late morning or afternoon soon after a rainy period. Male fire ants die soon after mating, while the fertilized queen lands and walks around to find a suitable nesting site, sheds her wings and begins digging a chamber to start a new colony.
How can you be sure you have fire ants?
The first step to managing fire ants is to properly identify the ant species. When you disturb the mounds with a long stick, fire ants explode out of the mound and travel vertically up whatever is disturbing them. This vertical climb is important because most native ants will not crawl up objects. If you do not actually see visible mounds in your garden or yard this does not mean there are no ants. In the heat of the summer, fire ants are often underground waiting for cooler temperatures.
In spring and fall, when weather is temperate, watch out for new mounds after a rainfall. Fire ants like to build their nests when the soil is damp and easy to maneuver. Fire ant mounds do not have central openings like other ant mounds. They enter and leave the mound through the side and underground tunnels. If you can safely examine the ants up close, you’ll see that fire ants are reddish brown to reddish black. Unlike other ant species which are uniform in size, fire ants vary in length.
How do you treat for fire ants?
When gearing up to do battle with fire ants, homeowners have many tools at their disposal. There are a plethora of insecticides for fire ant control including baits and drenches. Drenches work quickly but typically go straight down when applied to a mound; therefore the insecticide is not introduced into the well-developed chambers under the ground. As a result, you get less contact with the ants with these types of applications and less effective control.
Baits work the best, though they take at least two weeks to become effective. Fire ants are active when temperatures are above 75 degrees so treatment is most effective at this time. Be sure your bait is fresh and that no rain is forecasted within a 48 hour window of application. Some common fire ant baits on the market include Amdro, Amdro Firestrike, and Extinguish Plus.
Please Note: Any recommendations of brand names or listing of commercial products in this article are included solely as a convenience to the reader and do not imply endorsement by NC Cooperative Extension nor discrimination against similar products. Before applying any chemical, always obtain current information about its use and read the product label carefully.
Learn more about managing fire ants; Visit the national e-Xtension webpage on fire ants, extension.org/fire_ants, as well as Texas A&M’s fire ant websitefireant.tamu.edu/. For fall gardening and landscape care advice, visit ces.ncsu.edu, where you can post your questions via the ‘Ask an Expert’ link, or contact your local Extension office. If you live in Pender County, call 259-1235. In New Hanover County, call 910-798-7660. In Brunswick County call 910-253-2610.
Susan Brown is the horticulture agent with the New Hanover County Cooperative Extension of NC State University, College of Agriculture & Life Sciences.