Stings, in numbers, and fast. A disturbed mound produces dozens of ants on you within seconds, each stinging several times. Painful rather than medically significant for most people — the real risks are allergy and the sheer number of stings.
We identify, we don't diagnose. If you've been bitten or stung and symptoms develop, or you're worried, seek medical attention.
Size2–6 mm, varying within a single colony
MarkingsSmall and variable in size within one nest, 2–6 mm, reddish-brown with a darker abdomen · Mound of loose soil with no visible entrance hole on top
WhereOpen sunny ground — lawns, pasture, roadsides, park edges, sports fields. Mounds appear after rain.
SeasonActive year-round in the south; mounds most obvious after wet weather
How to tell it apart
Small and variable in size within one nest, 2–6 mm, reddish-brown with a darker abdomen
Mound of loose soil with no visible entrance hole on top
Boils out of the mound in seconds when it is disturbed
Runs upward on anything it lands on before stinging
A ring of small white pustules a day later is close to conclusive
Where you’ll find it
The southeastern and south-central United States, west through Texas and into parts of California. Still expanding.
Open sunny ground — lawns, pasture, roadsides, park edges, sports fields. Mounds appear after rain.
Active year-round in the south; mounds most obvious after wet weather.
How it behaves
The behaviour that matters is co-ordinated. Workers swarm out and climb before stinging, and something triggers them to sting together, which is why people describe a delay and then everything at once. Each ant grips with its jaws — that is the bite — and then pivots to sting repeatedly around the anchor point, producing the circular pattern. Colonies can hold hundreds of thousands of workers and relocate readily.
What a bite looks like
Immediate red weals, then within roughly 24 hours a small white or yellow pustule at each sting. Often in a ring or arc from one ant pivoting. The pustule is characteristic of fire ants specifically.
An immediate burning sting, which is where the name comes from, followed by intense itching for several days.
We identify, we don't diagnose. Do not break the pustules — that is how they get infected. Seek medical attention immediately for difficulty breathing, swelling of the face or throat, dizziness, or a rash away from the stings, and get advice for extensive stinging, small children or anyone known to react to insect stings.
A skin mark cannot confirm which animal caused it. Read the bug bite and sting guide for the limits and the symptoms that should end an online search.
You’ve found one indoors
Move away first and brush them off dry rather than trying to wash them off — water does not make them let go. Do not kick or poke a mound to see if it is active. If you are in the range, check the ground before sitting or putting a bag down, and look before children play barefoot.
Common questions
Do fire ants bite or sting?
Both, in sequence. The bite is a grip with the jaws; the sting comes from the other end and is repeated while it holds on. That is why the marks form a ring.
What is the white pustule?
A sterile blister that forms about a day after the sting. It is characteristic of fire ants and it is the clearest way to confirm what stung you. Leave it intact.
How dangerous is a fire ant sting?
For most people, painful and not serious. The genuine risks are an allergic reaction, which can be severe, and very large numbers of stings — which is a realistic outcome with this species in a way it is not with most others.
Is that mound in my lawn a fire ant nest?
If it is loose fluffy soil with no central hole and it erupts when disturbed, very likely. Native ant mounds usually have an obvious entrance and a far less dramatic response.
Sam Kieschnick · CC-BY