Biosecurity Spotters logo

Pharaoh ant (Monomorium pharaonis)

The Pharaoh ant is an introduced, highly adaptable ant that can establish persistent colonies inside buildings in Australia. It is a nuisance and can contaminate food and sensitive indoor areas, so early detection and careful control are important.

Key facts

Type: Pest animal, invertebrate.

Native to: Probably tropical Africa.

Established in: QLD, NSW, VIC, WA, NT.

Other names: Pharaoh's ant, Monomorium pharaonis.

Best time to act: Look for active trails when ants are foraging, and inspect year-round in heated buildings where colonies can remain active.

Identification

  • Workers are very small, about 1.5 to 2 millimetres long, and pale yellow to reddish brown.
  • The abdomen is usually darker than the rest of the body.
  • The waist has two small nodes, and the antennae end in a three-segmented club.
  • Workers often travel in visible trails between food or water and concealed nesting sites.
  • Colonies may have many queens and nest in warm, sheltered spaces such as wall voids, cupboards and equipment.
  • Look-alike: Other tiny household ants, including ghost ants and several small yellow ants, can look similar; colour alone is not a reliable way to identify them.
  • Look-alike: A hand lens can help reveal the two waist nodes and three-segmented antennal club used to distinguish Pharaoh ants.

Where it lives

In Australia it is most often found indoors in warm buildings, including kitchens, hospitals, food premises and other sites with sheltered nesting spaces, food and water.

Why it matters

  • Foraging ants can contaminate food and food-preparation surfaces.
  • Their small size and tendency to nest in inaccessible spaces can make infestations difficult to detect and eliminate.
  • They can be a concern in hospitals and other sensitive facilities because workers may forage across many indoor surfaces.
  • They do not have a painful sting, but their presence can create persistent nuisance and hygiene problems.

How it spreads

  • Colonies can spread by budding, when queens and workers establish new nests nearby.
  • Infested food, packaging, equipment and other goods can carry ants to new sites.
  • Moving items from an infested building without inspection can help transport the colony.

Control methods

  • Confirm the identification and locate trails and likely nesting areas; consider a licensed pest manager for persistent infestations or sensitive sites.
  • Use suitable ant baits registered for the purpose in Australia, following the product label and site requirements.
  • Avoid repellent sprays or disturbance of trails where possible, as these can disrupt colonies and contribute to budding.
  • Remove food and water sources, clean spills, seal accessible entry points and monitor the site after treatment; repeat control as needed.

Site hygiene and welfare

  • Inspect food, packaging, equipment and other goods for ants before moving them from an infested site, and keep food sealed during transport.
  • Clean food residues from vehicles and gear used at affected sites, and avoid transferring infested materials between buildings.
  • 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: Not prohibited or restricted. Not listed as prohibited or restricted matter in Queensland. 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: 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.

  • Queensland: Biosecurity Act 2014 (Qld), administered by Biosecurity Queensland (13 25 23)
  • 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
  • Western Australia: Biosecurity and Agriculture Management Act 2007 (WA), administered by the WA 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