Black Fire Ant: What to Know

Medically Reviewed by Jabeen Begum, MD on January 13, 2023
5 min read

Many species of ants live throughout the U.S. Most of them never become problematic enough for us to think of them as pests. But there are a handful of species that can cause both serious health problems and millions of dollars in damages. One of these problematic species is called the black fire ant or black imported fire ant. 

Learn how to identify this species so you know what to do when they start building mounds in your yard.

The scienfitic name for the black fire ant is Solenopsis richteri. They’re members of the Formicidae family, which contains most ant species. 

What do black fire ants look like? Black fire ants share several characteristics with other fire ants. These include: 

  • A two-segmented waist
  • Six legs
  • Two antennae — workers have 10 segments per antenna

Both this species of imported fire ant and Solenopsis invicta — the red imported fire ant — have a central tooth on the front portion of their heads. This tooth is flanked by two other teeth. 

One of the easiest ways to identify this species is by its distinctive black or dark-brown color. Black fire ants also have a yellow spot toward the end of the abdomen.

What’s the black fire ant lifecycle? Like most insects, black fire ants go through several distinct phases throughout their lifetimes. For black fire ants, this includes: 

  • Egg
  • Four larval stages — also known as instars
  • A pupal stage
  • Their adult form

The adult forms are the ones that you should learn to identify. This is the only stage where these ants behave as pests. 

Like other species of ants, there are both male and female insects. The females can take on specialized jobs like worker and queen.

There are two main types of fire ants in the U.S. — black imported fire ants and red imported fire ants. These are both in the Solenopsis genus. All black imported fire ants are members of the same species. 

Red imported fire ants arrived in the U.S. about 20 years after the black species. For the most part, they do much better than black fire ants in the same habitats. The main way you can tell them apart is by the color difference that’s implied in their names.

Black fire ants are native to South America. But human activity has accidentally spread them outside of their native range. You can now find them in the southeastern U.S., including:

  • Mississippi
  • Alabama
  • Tennessee 

In terms of habitat, they prefer cleared grasslands — like lawns and pastures. They also prefer to build their central mounds in moist areas. 

Black fire ants are highly adaptable and can survive in areas as diverse as swamps and mountains. But they cannot survive hard northern freezes or dry desert climates.

One major sign of a fire ant infestation is the presence of an ant mound in your yard. This species is very aggressive when it comes to mound-building. One mound can reach up to 3 feet in both height and width.

In certain places in South America, giant mounds can form with multiple queens inside. These can grow up to 10 feet high and 80 feet wide. 

When their mounds are disturbed, the ants will swarm out and attempt to defend their home.

If you live in an area where fire ants thrive, it can be difficult to keep them away from your yard. They need open spaces to construct their mounds. So simply having a yard is a good way to attract black fire ants. 

For the most part, black fire ants are outcompeted by both red fire ants and another species of ants — Nylanderia fulva — known as “crazy ants”. Black fire ants will try to build their homes in places that don’t have these other two species nearby.

Black fire ants act as pests in several ways. The most important problems for the majority of people in the U.S. are their venomous bites and stings. This can be very painful — especially when hundreds of ants are biting you at the same time.

Only female ants can sting, but both genders can bite. Each female typically bites down on an attacker and then stings the surrounding area seven to eight times before letting go. This can lead to a large number of stings in a short time.   

Luckily, they don’t enjoy interacting with people and will only come out of their mound if you step on it or otherwise try to disturb them.  

A black fire ant’s bite and sting symptoms can include: 

  • Burning and stinging sensations
  • Swelling
  • Pain
  • Formation of fluid-filled pustules that can last for weeks
  • Anaphylaxis, a severe allergic reaction

For certain people, this natural allergic response is so severe that a large attack can be fatal. Initial signs of an allergic reaction include trouble breathing and swelling in your face and lips. 

They can also damage farm equipment with their mounds. They even eat some crops. For example, they can occasionally wreak havoc on Brazilian potato crops. A large-scale infestation can be very expensive to manage.  

In other places, like Argentina, they’re considered more of a neutral presence than a pest-level threat.

The way to handle exposure to a black fire ant sting depends on the number of stings you get and how bad your reaction is. 

Get immediate medical attention if you believe that you or another person is having a severe allergic reaction. If you know that someone has a bee or wasp allergy, get them medical attention as soon as the stings occur instead of waiting for symptoms to develop.

In the case of a milder attack, you should: 

  • Wash the area with soap and water
  • Apply a cool compress
  • Take over-the-counter pain relievers as needed

Don’t pop any pustules that develop. They’re sterile if they’re left alone. 

If you have any immediate questions or concerns, you can contact Poison Control at 1-800-222-1222.

Countries that don’t already have black fire ant infestations tend to have strict identification measures in place so they don’t accidentally introduce this species. 

If you’ve already got some in your backyard, consider contacting a professional pest control company. Just make sure to do your research and choose a company that uses pest control methods that you approve of. This is the safest way to avoid injuring yourself or any loved ones in the surrounding area. 

Black fire ants can be annoying — even dangerous — pests to manage. You’ll stay safe by entirely avoiding their mounds until you can eliminate them.