Biosecurity Spotters logo

Argentine ant (Linepithema humile)

Argentine ants are established in Western Australia and can quickly eliminate other ants, especially native ants, from infested areas. They are difficult and costly to control, and management can involve ongoing, repeated use of residual contact insecticides.

Key facts

Type: Pest animal, invertebrate.

Native to: South America.

Established in: NSW, VIC, TAS, SA, WA.

Best time to act: Spring and summer, before populations peak, are the best times to manage Argentine ants.

Identification

  • They are small, slender, dark brown ants, 2.6 to 3.2 mm long, with a uniform shape and size.
  • Crushed ants may have a slightly greasy, musty or rancid odour.
  • Heavy trails are often visible on tree trunks, walls and bins.
  • Unlike most other ant species, Argentine ants readily climb onto a hand placed in their path.

Where it lives

In Western Australia they occur around paths, garden beds, lawns, kerbs, tree trunks and reticulation piping, and may enter buildings in large numbers in search of food and moisture.

Why it matters

  • They quickly eliminate other ants, especially native ants, from infested areas.
  • They eat a wide range of foods, including sweet drinks, pet food, meat, and live and dead insects.
  • They can rob and stress commercial beehives and be a significant pest in orchards and horticulture.
  • They can attack nesting birds, hatching eggs, insects and other fauna, and readily bite, although their bites are not painful.

How it spreads

  • They spread unintentionally when infested materials are transported, including soil, turf, pot plants, foods and garbage.
  • Check pot plants and other plant material before receiving, moving or giving it away.

Control methods

  • Manage ants in spring and summer, before populations peak, and seal cracks and crevices where they enter buildings, watching for alternative routes.
  • Small populations may be controlled with sugar-based gel baits; low-toxicity liquid insecticides can be used as barriers. Always follow product label directions.
  • Insecticidal dusts and powders, and granular ant baits, are not recommended; contact a professional pest controller for severe infestations.
  • For identification help or unsuccessful control, contact PaDIS on +61 8 9368 3080 or at padis@dpird.wa.gov.au, or use the MyPestGuide Reporter app.

Site hygiene and welfare

  • Check pot plants and other plant material to ensure they are free of ants before moving or sharing them.
  • 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: General biosecurity duty. Not prohibited matter in NSW. The general biosecurity duty applies: anyone dealing with it must prevent, eliminate or minimise the risk it poses.
  • 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: Permitted, not declared. Listed as a permitted organism in WA, so it can be brought in, but it is not a declared pest.
  • Tasmania: Not a declared pest. Not a declared pest or prohibited matter in Tasmania. Importing animals is still controlled by Biosecurity Tasmania.
  • 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
  • Victoria: Catchment and Land Protection Act 1994 (Vic), administered by Agriculture Victoria
  • Tasmania: Biosecurity Act 2019 (Tas), administered by Biosecurity Tasmania
  • South Australia: Landscape South Australia Act 2019 (SA), administered by the regional landscape board
  • Western Australia: Biosecurity and Agriculture Management Act 2007 (WA), administered by the WA Department of Primary Industries and Regional Development

Sources