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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.

Written by PestMan Editorial TeamTechnical review pendingPublished Updated
Colony
One or many queens; workers forage
Peak season
Spring and summer, around rain
Key tell-tale
Narrow waist, elbowed antennae
Report
Suspected fire ants (Qld/NSW)
Risk level
Low (higher for fire ants)

Ant identification

How to recognise ants

  • Three body segments with a narrow "waist" (petiole) between thorax and abdomen.
  • Elbowed (bent) antennae. Termites, which are often confused with ants, have straight, bead-like antennae and no narrow waist.
  • Winged ants (reproductives) appear in swarms, usually on warm, humid days after rain.
  • Size and colour vary by species: tiny pale ghost ants, small black house ants, and light-brown coastal brown ants with some big-headed workers.

Common species in Australia

Coastal Brown Ant

Pheidole megacephala

An introduced, light-brown ant that forms huge multi-queen colonies and leaves piles of loose soil between pavers and along slab edges. One of the most common nuisance ants in Queensland.

Black House Ant

Ochetellus glaber

A small, shiny black native ant that forms long trails into kitchens and bathrooms searching for sweet food and water.

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.

Ant overview

Australia has thousands of ant species, but only a small number regularly forage inside homes. Common household ants include the coastal brown ant, the black house ant, tiny ghost ants and Argentine ants in some southern areas.

The ants you see are workers from a colony that may be under paving, in a wall void, in a pot plant or in the garden. Understanding why ants follow a line helps explain why wiping up a trail rarely solves the problem.

Red imported fire ants are an invasive species present in parts of South East Queensland, with detections in northern NSW. Suspected fire ants must be reported to the National Fire Ant Eradication Program; do not disturb or treat the nest yourself. See fire ants in South East Queensland.

Behaviour

  • Workers lay pheromone trails that other ants follow to food and water.
  • Activity increases in warm weather and often surges before and after rain.
  • Some species have multiple queens and split into new colonies when disturbed by sprays.

Habitat

  • Under paving, along path edges and in lawn and garden beds.
  • In wall voids, skirting boards, window frames and electrical fittings.
  • In pot plants, mulch and under rocks or timber.

Lifecycle

  • Ants develop by complete metamorphosis: egg → larva → pupa → adult.
  • Colonies are led by one or more queens; workers are sterile females.
  • Many colonies send out winged males and queens once or twice a year to start new colonies.

Food sources

  • Sugary foods, honeydew from sap-sucking insects, fruit and sweet drinks.
  • Protein and fats such as pet food, meat scraps and grease.
  • Water, which draws ants to sinks, bathrooms and pot plants in dry weather.

Entry points

  • Gaps around window and door frames.
  • Cracks in slabs, grout and along skirting boards.
  • Pipe and cable penetrations, especially under sinks.
  • Plants, branches or garden beds touching the house.

Infestation signs

  • Trails of ants along benches, skirting boards or window sills.
  • Small piles of soil between pavers or along slab edges (common with coastal brown ants).
  • Winged ants emerging indoors, which may indicate a nest inside the structure.

Health implications

  • Most household ants are a nuisance and food-contamination risk rather than a health threat.
  • Some ants bite or sting. Fire ant stings are painful and can cause severe allergic reactions in some people.
  • Seek urgent medical help (call 000) for any sign of anaphylaxis after a sting.

Prevention

  • Clean up food and sweet spills promptly and store food in sealed containers.
  • Fix leaking taps and reduce standing water around sinks.
  • Trim plants and branches away from walls and roofs.
  • Seal obvious gaps around frames, pipes and cables.

Treatment overview

  • Baits carried back to the colony are often more effective than surface sprays, which can scatter some species into multiple nests.
  • Identifying the species matters, as different ants prefer sugar, protein or oil-based baits.
  • Fire ants are managed under a national eradication program; report them rather than treating them yourself.
Product safety

If you use any pest product, read the label first and follow it exactly — it is a legal requirement in Australia. Keep products away from children, pets and food areas as the label directs.

Questions about ants

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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.

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Cockroaches

Fast, flat-bodied insects that hide in warm, damp gaps and come out at night to feed. A few introduced species cause most household problems in Australia.

Silverfish

Primitive, wingless insects with silvery scales that live in humid, undisturbed places and feed on starch, paper and glue. They damage books and fabrics but are harmless to health.

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Sources & further reading

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