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Tropical fire ant (Solenopsis geminata)

Tropical fire ants are invasive ants that can establish in warm parts of Australia, including Queensland. Their painful stings and effects on native invertebrates, seeds and young plants make them a concern for people, landholders and site crews.

Key facts

Type: Pest animal, invertebrate.

Native to: Tropical parts of the Americas.

Established in: NSW, NT.

Other names: Ginger ant.

Best time to act: Search for nests and foraging workers in warm conditions, and report suspected colonies promptly.

Identification

  • Workers vary in size, generally from a few millimetres long to around 6 mm.
  • The head and thorax are usually reddish brown, while the abdomen is darker.
  • Large workers have especially broad, oversized heads compared with smaller workers.
  • Antennas have 10 segments and end in a two-segment club.
  • Colonies nest in soil, often forming a low mound in open, sunny ground; workers can sting painfully.
  • Look-alike: Red imported fire ants and some native ants can look similar in colour and may sting; the unusually large-headed major workers help distinguish tropical fire ants.
  • Look-alike: Identification can be difficult from appearance alone, so have a suspect ant checked by a biosecurity officer or an ant specialist.

Where it lives

In Australia, they are associated with warm areas and open, disturbed sites such as lawns, gardens, roadsides and agricultural land, where they nest in soil.

Why it matters

  • Their stings cause painful burning and may produce pustules; stings can also trigger severe allergic reactions in some people.
  • They prey on other invertebrates and consume seeds, potentially affecting native species and ecological processes.
  • They can damage seedlings and create problems for people working or living near infested sites.

How it spreads

  • Colonies can spread through mating flights by winged queens and, in some circumstances, by colony budding.
  • Infested soil, potted plants and other materials or equipment carrying ants can move colonies to new sites.

Control methods

  • If you suspect tropical fire ants, do not disturb the nest or move soil and materials from the site; report the find to Biosecurity Queensland.
  • For confirmed infestations, follow instructions from the relevant biosecurity authority rather than attempting an unapproved treatment.
  • Use only ant baits or insecticides registered for the intended use and follow their label directions; seek help from a licensed pest manager where appropriate.
  • Digging out a nest alone is not a reliable control method; revisit treated sites and carry out any follow-up treatment or surveillance as directed.

Site hygiene and welfare

  • Before leaving a suspect site, check and clean soil and ants from vehicles, machinery, boots and equipment.
  • Do not transport soil, potted plants, fodder or other materials from an infested or suspect area unless cleared or directed by biosecurity authorities.
  • Use methods set out in the national model codes of practice and standard operating procedures for the species.
  • Coordinate control with neighbours and the local government biosecurity plan, as isolated effort is quickly undone by reinvasion.

Classification by state

  • Australia (national): No national listing. Managed under state and territory law.
  • Queensland: Prohibited matter. Report it to Biosecurity Queensland on 13 25 23 within 24 hours and do not move or deal with it. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: Prohibited matter. It is an offence to deal with it, and you must notify NSW DPIRD as soon as you become aware of it.
  • Victoria: Not declared. Not declared under the Catchment and Land Protection Act 1994. Other Victorian laws may still apply.
  • South Australia: Not declared. Not declared under the Landscape South Australia Act 2019. Other laws may still apply.
  • Western Australia: Declared pest (C1), prohibited. C1 Exclusion: to be kept out of WA, or out of the parts of WA where it is not established. Report any sighting to DPIRD. It must not be brought into WA (prohibited organism).
  • Tasmania: Declared pest. It is a declared pest under the Biosecurity Act 2019 (Tas). Report sightings to Biosecurity Tasmania and follow any management requirements.
  • Northern Territory: Not a declared pest. Not on an NT declared or prohibited list. Check with the NT Government before keeping, moving or releasing it.
  • Australian Capital Territory: Not declared. Not declared under the Biosecurity Act 2023 (ACT). A general biosecurity duty still applies.

Legal obligations

Every state and territory places a duty on landholders and people working on land to prevent the spread of invasive species, such as the general biosecurity obligation in Queensland and the general biosecurity duty in New South Wales. Declarations and control requirements differ between states and local government areas, so check the current official list before work starts.

  • New South Wales: Biosecurity Act 2015 (NSW), administered by NSW Department of Primary Industries and Regional Development
  • Northern Territory: Territory Parks and Wildlife Conservation Act 1976 (NT), administered by NT Department of Lands, Planning and Environment

Sources