How to Identify & Control Fire Ants

In general, ants are a nuisance, but some species are more than mere pests. Fire ants, found throughout western and southern parts of the U.S., are a particular problem because of their painful bites and stings. These ants will aggressively protect their mounds by attacking interlopers who either deliberately or accidentally disturb the mound. We're going to help you learn how to identify this southern pest and give you practical steps to get rid of fire ants in your yard and home.

Identifying Fire Ants

Although multiple fire ant species exist, arguably, the most impactful species of fire ant in the United States is the invasive red imported fire ant (RIFA). The queen and worker RIFAs have a reddish-brown head and thorax with a black rear segment (although there may be variations in color). Male swarmers are completely black. Workers are polymorphic (meaning they vary in size), ranging from 1/16-1/4 inch in length. Fire ant workers have a venom-injecting stinger as well as mandibles used for biting. Warm weather-loving pests, fire ants are most active when outdoor temps range from 65ºF to 90ºF. 

One way to distinguish fire ants from other red ants is that they have a 2-segmented pedicel, which looks like two bumps on the ‘waist' of the ant—the area between the thorax and abdomen. Their thorax lacks spines, and they also have 10 distinct antennal segments with a 2-segmented club at the ends.

Where Do Fire Ants Live?

Many people are able to identify fire ants by spotting their telltale mounds. These ants are typically ground-nesting and will build their mounds in virtually any kind of soil, but tend to prefer sunny locations that include lawns, fields, and pastures. There is a tendency for fire ants to build mounds near driveways and sidewalks that absorb and give off heat. People have also spotted their mounds in rotting logs, near trees, and even beneath buildings. However, a lack of mounds does not mean that there are no fire ants present. Fire ants also create an elaborate underground tunnel system that can extend up to 25 feet away from a mound.

Mature mounds are, on average, 10-24 inches across and 6-18 inches high but may be larger or smaller. A large colony can have as many as 250,000 worker ants that are well known for their active and aggressive natures; however, the average fire ant colony typically consists of around 80,000 workers. Even if you knock over an ant mound, the workers will either just rebuild it or move the mound to another location, probably not far from the original mound.

During hurricanes or other flooding, fire ants will often be forced to leave their nests to look for dry land. To do that, they will form living rafts that drift on the water until the ants reach a landing spot, such as a tree trunk or the foundation of your house. They may even come inside the house to search for food.

What Do Fire Ants Eat?

Fire ants are omnivores that will feed on almost anything, including plants and animals. Their food preference depends on the nutritional needs of their colony throughout the year. They feed on insects, honeydew, sugars, oils from seeds or oily meat or nuts. These ants will also dine on carrion (dead, decaying animals) that they happen to locate when foraging.

Do Fire Ants Bite or Sting?

While fire ants do bite, the bigger problem is their sting, which is what actually injects the venom that causes painful and itchy red bumps or welts. While a single sting for most people and pets is bothersome, it is more common to be stung multiple times by multiple ants. Hundreds of ants can sting multiple times during a single attack which can lead to severe reactions even those with a strong immune system. If a person experiences a serious reaction, like nausea, sweating, or shortness of breath as the result of a fire ant sting, they should seek immediate medical care. A very small percentage of people in the U.S. (approximately 1-2%) are at risk for anaphylaxis if stung by fire ants. 

Most of these attacks occur when the ants' mound is disturbed—fire ants are aggressive when it comes to protecting their territory. The key to avoiding being stung outdoors is to be vigilant in areas where they are likely to be present, and to watch where you step in order to avoid disturbing the nest. Fire ants are small and can easily get into shoes or clothing when the nest is disturbed, so it's just not worth it to upset them.

How Do I Get Rid of Fire Ants?

Most often, fire ants are outside in your yard and require a 2-step treatment that destroys existing mounds now and then treats the whole yard to prevent them from coming back. While not as common, fire ants can get inside, which requires spot treatment to kill ants you see or, preferably, a preventative treatment to keep them from getting indoors in the first place. 

How to Get Rid of Fire Ants in Your Yard

To kill fire ants in your yard, use the 2-step method:

1. Kill the queen and her colony by applying a dust or granular product like Ortho® Orthene® Fire Ant Killer1 to the mound, following package directions. Use wherever and whenever you see a mound of any size. Another option for destroying the mound is to surround it with Ortho® Fire Ant Killer Mound Treatment.
2. Apply a broadcast treatment like Ortho® Fire Ant Killer Broadcast Granules or Ortho® Orthene® Fire Ant Killer Lawn & Landscape Broadcast Ready-to-Spray over the entire lawn. This will help kill any fire ants hiding in the grass, plus continue to control new fire ant mounds.

How to Prevent Fire Ants from Getting Inside Your Home

Fire ants can get into the home just like other ants do. They may create nests that put them close to foundation cracks, for instance. They may also enter through HVAC units, typically after being displaced following rain or flooding. They may also access the home via electrical boxes.

One way to help prevent these pests from getting into your home is by caulking cracks and holes. You can also create a barrier around your home with Ortho® Home Defense® Insect Killer for Indoor & Perimeter2. If the fire ants are already nesting in your home, kill them with Ortho® Home Defense® Ant, Roach & Spider Killer2. Remember to follow all label directions when using any pest control product.

If you're in the South, you know you don't want fire ants in your yard. Take steps to know a fire ant when you see one and get rid of them the right way—without getting any of those painful stings!