Biosecurity Spotters logo

African big-headed ant (Pheidole megacephala)

It is well established on mainland Australia and is a major threat to biodiversity and ecosystems. It can displace native invertebrates, including other ant species, and can damage plants and cause problems in buildings.

Key facts

Type: Pest animal, invertebrate.

Native to: Africa.

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

Best time to act: The ants are most active in warm, dry conditions, which is the best time to look for them.

Identification

  • Major workers are ginger-brown with very large, dark-coloured heads, almost half the size of their bodies.
  • Minor workers range from light to dark brown.
  • Workers are small, about 2 to 4 mm long, and move quickly and erratically.
  • They are aggressive and most active in warm, dry conditions.
  • Look for soil mounds, particularly along concrete edges, and nests in lawns, tree cracks, paving crevices, hollow logs or pot plants.

Where it lives

In Australia, the species is established on the mainland and has been found within the settlement on Lord Howe Island, in and around infrastructure and in natural environments.

Why it matters

  • It can out-compete and displace native invertebrates, especially other ant species, and threatens biodiversity and ecosystems.
  • Rainforest ecosystems are particularly at risk.
  • As a sap-sucking insect, it can damage fruit and plant roots.
  • Large colonies can form in buildings where food scraps are available, and ants can damage electrical items such as power points.

How it spreads

  • Importation of plants, timber and building materials is identified as a threat to the Island.
  • The species is well established on mainland Australia and remains a threat to Lord Howe Island.

Control methods

  • LHIB's response includes delimiting surveys across the island to establish the extent of the infestation.
  • The stated treatment is Amdro® Pro granular ant bait to control and contain known infestations and newly occurring hotspots.
  • Two treatments, three months apart, are recommended, followed by monitoring and re-treatment if necessary.
  • Report suspected sightings to the LHIB Biosecurity team and provide a photograph or sample if possible; the listed phone number is 02 6563 2066.

Site hygiene and welfare

  • Pay particular attention to plants, timber and building materials, which are identified as importation pathways of concern.
  • 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: Prohibited matter on Lord Howe Island. It is prohibited matter on Lord Howe Island, so it must not be brought there, and any sighting there must be reported to NSW DPIRD. Elsewhere in NSW the general biosecurity duty applies.
  • 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.

  • 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
  • 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
  • Northern Territory: Territory Parks and Wildlife Conservation Act 1976 (NT), administered by NT Department of Lands, Planning and Environment

Sources