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Fire Ants in California: Southern vs Imported & the Sting
Yes, California has fire ants — mostly the native southern fire ant. Here is how to tell them from imported red fire ants, the sting risk, and what to do.
Yes, California has fire ants — but probably not the ones you are picturing. Most fire ants in the Central Valley are the native southern fire ant (Solenopsis xyloni). The notorious imported red fire ant is also in California, but it is invasive and limited to certain quarantined areas. Both sting, and telling them apart matters.
A bicolored southern fire ant — reddish head and thorax, darker abdomen — on a soil mound.
Southern fire ant vs imported red fire ant
| Southern fire ant (native) | Imported red fire ant (invasive) | |
|---|---|---|
| Status | Native to California | Invasive; under CDFA quarantine |
| Where in CA | Common, including the Central Valley | Limited areas of Southern & Central CA |
| Mound | Loose, irregular, scattered soil | Dome-shaped mound, no central opening |
| Aggression | Stings when disturbed | Highly aggressive; swarms and stings en masse |
| Sting | Painful | Painful; more medically significant in numbers |
How to identify a fire ant
Fire ants are small — about 1/8 to 1/5 inch — and typically bicolored, with a reddish-brown head and thorax and a darker abdomen. They nest in soil and you will often find them in loose mounds in lawns, gardens, and along walkways. The surest sign is behavioral: disturb the nest and they boil out and sting.
A fire ant sting burns, then forms an itchy raised welt or pustule that can last for days. Most people are fine, but stings can cause a severe allergic reaction in sensitive individuals — seek medical help for swelling beyond the sting site, hives, or trouble breathing. Keep children and pets away from active mounds. For identification and quarantine status, see UC IPM and the CDFA fire ant profile.
Where fire ants show up in the Central Valley
Around Fresno, southern fire ants nest in sunny, open soil — lawns, garden beds, and the edges of walkways and driveways. Imported red fire ants are managed under a state quarantine and are mainly a concern in specific Southern and Central California areas; if you suspect them, identification matters because reporting and treatment differ.
What to do about fire ants
1. Don’t disturb the mound. Kicking or raking it triggers mass stinging and scatters the colony.
2. Treat the mound and bait. Fire ants are best handled with a combination of targeted mound treatment and slow-acting bait that reaches the queen.
3. Protect people and pets. Keep kids and animals clear of active mounds until they are treated, especially in play areas.
When to call a pro
Stinging ants near a home, lawn, or play area are worth handling professionally — both for safety and because mounds re-form if the colony is not reached. Our ant control service identifies the species and treats the nests directly.
See our ant control process →Fire ants in California FAQ
Does California have fire ants?
Yes. Most are the native southern fire ant, found throughout the Central Valley. The invasive imported red fire ant is also present but limited to certain quarantined areas of the state.
What kills fire ants?
A combination of targeted mound treatment plus slow-acting bait that workers carry to the queen. Spraying the surface alone leaves the colony intact, so the mound returns.
Why do I suddenly have fire ants?
Warm weather, irrigation, and open sunny soil encourage mound-building. A new mound in a lawn or garden often appears after watering or a stretch of heat.
Are California fire ants dangerous?
Their sting is painful and can cause a severe allergic reaction in sensitive people. They are not usually life-threatening, but mounds near children or pets should be treated promptly.
Are harvester ants the same as fire ants?
No — harvester ants are larger seed-eaters that build big bare-soil mounds and also sting. See our harvester ant guide to tell them apart.
Stinging ants in the yard? We’ll identify and treat them safely.
Call (559) 472-8200 or request a no-cost inspection — species ID and direct mound treatment that protects kids and pets.