Red Imported Fire Ant vs Argentine Ant
Red Imported Fire Ants and Argentine ants are easy to mix up at a glance, but a few details separate them quickly. Here is how to tell which one you found and what, if anything, you should do about it.
Quick answer
Check for this first. A red imported fire ant has mixed sizes of copper-red workers in one colony, while an Argentine ant has uniform light-brown body with one flat node.
Side-by-side comparison
| Red Imported Fire Ant | Argentine Ant | |
|---|---|---|
| Group | Ants | Ants |
| Scientific name | Solenopsis invicta | Linepithema humile |
| Size | 2–6 mm | 2–3 mm |
| Colors | Red and Brown | Brown |
| Legs | 6 legs | 6 legs |
| Wings | No | No |
| Bites or stings | Bites, Stings | No |
| Risk | Health risk | Nuisance |
| Key feature | Mixed sizes of copper-red workers in one colony | Uniform light-brown body with one flat node |
Key differences
- Size: Red Imported Fire Ants are larger, reaching 6 mm, while Argentine ants top out around 3 mm.
- Color: Red Imported Fire Ants are red and brown; Argentine ants are brown.
- Risk: the red imported fire ant can cause medically significant bites, stings or disease, while the Argentine ant is a nuisance pest but not a health threat to most people.
- Where found: look for red imported fire ants in lawns and grass and in yards and on patios; Argentine ants turn up in the kitchen and in gardens and on plants.
- Signature feature: Red Imported Fire Ants: mixed sizes of copper-red workers in one colony. Argentine Ants: uniform light-brown body with one flat node.
How to identify red imported fire ants
A small, aggressive reddish-brown ant that builds dome-shaped mounds of loose soil in sunny lawns and fields across the southern US. When disturbed, workers swarm and sting repeatedly.
- Mixed sizes of copper-red workers in one colony
- Loose, fluffy dirt mounds with no central opening
- Swarms quickly up legs when the mound is disturbed
How to identify Argentine ants
A small, light-to-dark brown ant that forms huge, cooperating supercolonies. Wide, busy trails often stream into kitchens during hot or rainy weather.
- Uniform light-brown body with one flat node
- Very wide, steady trails several ants across
- Musty, greasy odor when crushed
Which one is more dangerous?
The red imported fire ant carries more risk. Fire ant stings burn, form white pustules, and can cause severe allergic reactions in sensitive people.
Fire ant stings burn, form white pustules, and can cause severe allergic reactions in sensitive people. Argentine ants don't sting and rarely bite; they protect aphids and scale insects on garden plants.
Where and when you'll see each
Red Imported Fire Ants turn up in lawns and grass and in yards and on patios, mostly in spring, summer and fall. Argentine Ants turn up in the kitchen and in gardens and on plants, mostly in spring, summer and fall.
Where you found the bug is itself a strong clue, since these two rarely share the same spots.
What to do if you find one
Red Imported Fire Ants: Broadcast a fire ant bait across the yard in warm, dry weather. Read the full removal guide for more.
Argentine Ants: Apply sugar-water baits outdoors along trails. Read the full removal guide for more.
Biology: ants
Ants live in colonies ruled by one or more egg-laying queens. The workers you see are sterile females foraging for the rest of the colony, so killing visible ants rarely solves anything. Winged ants, called swarmers, appear when a mature colony sends out new kings and queens.
Frequently asked questions
What is the main difference between red imported fire ants and Argentine ants?
Size: Red Imported Fire Ants are larger, reaching 6 mm, while Argentine ants top out around 3 mm.
Which is bigger, a red imported fire ant or an Argentine ant?
Red Imported Fire Ant: 2–6 mm. Argentine Ant: 2–3 mm.
Do red imported fire ants or Argentine ants bite?
Red Imported Fire Ants can bite and can sting. Argentine Ants do not bite.
Where are they usually found?
Red Imported Fire Ants: in lawns and grass and in yards and on patios. Argentine Ants: in the kitchen and in gardens and on plants.