Tropical fire ant

Appearance

• Adults have a shiny brown-orange body.
• About 2–5mm long.
• Some workers have an obvious oversized square head.
• Can be confused with red imported fire ant, which has a coppery brown head and body, and darker abdomen.

Behaviour

• Aggressive with a painful sting used for colony defence, prey capture and antimicrobial action.
• Attack in numbers when the colony is disturbed.
• Produce red itchy bumps that can last for days and sometimes lead to an allergic reaction.
• Can live in dry areas.
• Tend mealybugs and aphids that produce honeydew which affects plant health and impacts on agriculture and horticulture.
• Feed on any plant or animal material such as grains, seeds and seedlings, honeydew, arthropods and decaying matter. They prefer food with high content of protein and can kill hatchling turtles, eat eggs of birds, reptiles and amphibians, and injure nestling seabirds. These ants are also attracted to many human foods rich in carbohydrates and fats.

• Nests are found in the soil in a variety of disturbed, mostly sunny places.
• Slightly raised and loose soil.
• Several entrance holes with dirt spread widely around.
• Foraging tunnels radiate for several metres just below the surface.
• Mature colonies have up to 100,000 individuals and multiple queens.
• Oldest workers usually forage within 15m of the nest but foraging can occur up to 50 metres from the nest.
• A new queen can fly up to 2km from the original nest. These flights occur during warmer months.

These ants have recently been detected at the Port of Brisbane and an eradication program has commenced.

They were previously detected in South East Queensland in 2002 and eradicated.

They are now established at Ashmore Reef, Christmas Island, and the Northern Territory. They have recently been found in areas of Western Australia. They are established in most parts of Africa, South East Asia, the Pacific region, and northern Australia.

• Generalist predators that can attack many types of animals and insects.
• Despite being small, tropical fire ants are highly aggressive and attack any intruder that disturbs its nest.
• They defend their territory by swarming, clutching their victim with their jaws before stinging and injecting an alkaloid venom called solenopsin.

Environmental

• Agricultural and urban pest and also can affect natural ecosystems.
• Are a dominant species once they become established—pushing out native ants.
• Are omnivorous—eating anything from seeds to small mammals and birds.

Economic

• Worker ants indirectly damage crops by protecting pest insects such as aphids so they can eat their honeydew.
• Can interfere with harvesting by stinging agricultural workers.
• Damage infrastructure by chewing holes through irrigation hoses.

We use luring and observation for surveillance. Lures consist of syrup or sausage in small jars placed on the ground approximately 5m apart, alternating between the 2 attractants. Lures are placed and collected after 1 hour and ants are identified under a compound microscope by an entomologist. Additionally, trained officers perform a visual inspection to look for and sample any suspect ants.

You can do your part to stop their spread. Check machinery, equipment, pot plants and other sources of soil before you move it.

Tropical fire ants are prohibited matter under the Biosecurity Act 2014. The Act requires everyone to take all reasonable and practical steps to minimise the risks associated with tropical fire ants under their control. If you see an increase of small brown-orange ants that sting and bite, report promptly to Biosecurity Queensland on 13 25 23.