How do you identify fire ants?

Written by Joe Ballenger

Question submitted by Bridget Mendel’s first grade class.

Fire ants are a really big problem. They’ve got a really nasty attitude towards both people and other bugs. They’re really common, and it’s too easy to step in their nests.

A lot of people get hurt by accidentally stepping on fire ant mounds, but unfortunately a lot of people confuse harmless ants with fire ants.

So how can you tell a fire ant nest from a harmless bug nest?

1.) Location

Fire ants aren’t going to be found everywhere. They’re native to tropical parts of South America, so they don’t overwinter very well. In the southern US, they’re the most common ants. However, they’re not found in the Northern US at all.

The image below is from the USDA, which keeps records of where fire ants are found. Their range is slowly spreading north, but if you’re further north than Missouri…you won’t have a problem with them.

Fire ant range map, courtesy of the USDA

Fire ant range map, courtesy of the USDA

2.) Size and color.

Fire ants are pretty small ants, typically about a quarter inch long. They’re also a rust-red and not a bright red. You have to look at big photographs to really see their colors. When tromping around in the grass, they look black to brown from far up.

There’s a great picture floating around the internet which shows the colors and the size of the ants. It can be seen here. Unfortunately the image is copyrighted so we can’t post it on this blog, but it’s worth checking out.

Larger red ants sometimes confused with fire ants, but these are typically brighter red than fire ants.

A red carpenter ant, Camponotus castaneus. This common species is sometimes confused for fire ants. Compare this species to the pictures in the link above.

A red carpenter ant, Camponotus castaneus. This common species is sometimes confused for fire ants. Compare this species to the pictures in the link above. Picture courtesy of myrmecophile77, via flikr. License info: CC-BY-NC2.0

3.) Nest mound shape

Lots of ants make a nest with one entrance and exit, but not fire ants. Their nests are really big and don’t have a hole in the top. They look like a floofy mound of dirt, and can be either hard or soft depending on where they’re building.

Textbook fire ant mound. Image courtesy of Robert Nunally via flikr. License info: CC BY 2.0

Textbook fire ant mound. Image courtesy of Robert Nunally via flikr. License info: CC BY 2.0

4.) Behavior

Fire ants have a very unique defensive behavior. When their nest is disturbed, they pile out of their nest and start indiscriminately attacking everything that’s nearby.

Obviously, I don’t want to encourage people to harass fire ant nests…but if you live in the south and you find an ant nest looks like the one in the video above, then it’s best you avoid it.

The Bottom Line

We’ve talked about how scientists figure out which bug they’ve got before by using documents called ‘keys’. However, you don’t need to bring a key with you when you’re tromping around outside.

To recognize fire ants, you need to pay close attention to your surroundings. If you’re in the south, and you find an ant nest which matches what you see above…then it’s probably a fire ant nest.

All bugs should be treated with respect, and this goes double for any insect which is capable of hurting a human. Keep your distance, and consult a pest management professional for advice on control options if this is needed.

This entry was posted in Behavior, Ecology, Education, Taxonomy and tagged , . Bookmark the permalink.

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