Red Imported Fire Ant
Solenopsis invicta
An invasive South American ant first found in Brisbane in 2001 and now the target of a national eradication program. It builds loose soil mounds in open areas, swarms when disturbed and stings repeatedly. Suspected fire ants must be reported, not treated.
- Size
- 2–6 mm, mixed sizes
- Colour
- Coppery-brown, darker abdomen
- Nest
- Loose soil mound, no entry holes
- If found
- Don't disturb — report it
Questions about the Red Imported Fire Ant
How to identify a Red Imported Fire Ant
Identification
- Workers are small, about 2–6 mm, and come in mixed sizes within the same nest.
- Coppery-brown head and body with a darker brown to black abdomen.
- Nests are mounds of loose, crumbly soil, flat or dome-shaped, up to about 40 cm high, with no obvious entry holes on top.
- When a mound is disturbed, large numbers of ants pour out quickly and run up objects, including legs and tools.
Where it lives
- Open, sunny areas: lawns, parks, paddocks, garden beds, road verges and the edges of paths and driveways.
- Also under pavers, rocks, logs and along foundations, and in potted plants and landscaping materials.
- Mounds are often most visible after rain.
Behaviour
- Highly defensive: workers swarm and sting repeatedly when the nest is disturbed.
- Colonies can have one or many queens and can contain hundreds of thousands of ants.
- Winged queens fly to start new nests, and colonies also spread when soil, mulch, turf, hay or potted plants are moved.
Why it matters
Stings cause a burning pain followed by white pustules, and can cause severe allergic reactions (anaphylaxis) in some people. See fire ant sting first aid.
Fire ants harm pets, livestock and native wildlife, damage crops and electrical equipment, and affect outdoor life in infested areas.
They are managed under the National Fire Ant Eradication Program. In Queensland, suspected fire ants must be reported promptly (the Program asks for reports within 24 hours — check the current rules on its website). See the fire ant guide.
Commonly confused with
Other ant species
Ant guides
How to Pest-Proof Your Home
A practical, room-by-room approach to reducing pests without relying on chemicals: remove what attracts them, close the ways in, and make your property less comfortable for them.
GuideCommon Brisbane Household Pests
A Brisbane-specific overview of the pests residents meet most often, when they are active, and what the subtropical climate, storms, creeks and Queenslander homes mean for pest pressure.
GuideFire Ants in South East Queensland
How to recognise red imported fire ants, what to do if you find them or are stung, how the National Fire Ant Eradication Program works, and what the biosecurity rules mean for households in South East Queensland.
Ants by location
More about ants
Ants
Social insects that live in colonies and follow scent trails to food and water. Most ant problems in homes are nuisance foraging trails from colonies outside the house.
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Sources & further reading
- National Fire Ant Eradication Program — identifying and reporting fire ants — National Fire Ant Eradication Program
- Queensland Museum — insects, spiders and animals of Queensland — Queensland Museum
- healthdirect — bites, stings and infection information — healthdirect Australia
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