Fire ants are forming rafts to survive and travel on flood waters caused by ex-Tropical Cyclone Alfred in south-east Queensland as experts warn extreme weather events could sweep the highly invasive species into other parts of Australia.
Footage captured in the Scenic Rim and northern Gold Coast in recent days shows red imported fire ants (Rifas) grouping together and floating on flood waters. Clumps of the ants can then be seen forming nests on previously uninfested land after waters receded.
Kirsty McKenna, who filmed the fire ants rafting on her Allenview property, said entire colonies were clinging on to debris and staying buoyant, ready to make nests on dry ground.
“There’s piles of them everywhere, floating through the waterway, heading to the Logan River,” she says in the video.
Reece Pianta, advocacy manager at the Invasive Species Council, said the colonies were likely to have spread several kilometres from their starting points, with larger rafts more likely to have travelled further.
“The risk of fire ants spreading in flood waters after a disaster is very high and we’re very concerned about it,” he said.
The rare phenomenon was also filmed in floods early last year. It was the first time Pianta had seen footage of the unusual adaptive behaviour in Australia.
“This year, the rafts appear to be much larger, they’re pointing to higher densities of fire ants and bigger colonies,” he said.
Heavy rainfall in southern Queensland will spread high-density infestations regionally and could also sweep fire ants into carrier materials such as turf, which could then inadvertently relocate the pests to other parts of the country, he said.
“We’re lucky fire ants aren’t in the Murray-Darling basin but this is the kind of event that could see them spread into New South Wales if they were,” he said.
McKenna, who lives close to turf and hay farmers whose products travel beyond Queensland, said she was “worried if we don’t reduce the fire ant infestation, it will undermine Australia’s eradication efforts”.
Rifas are native to South America and are believed to have arrived in Australia via infected materials on ships at the port of Brisbane in 2001 but may have been present in the country since 1992. They are dark reddish-brown with darker abdomens and pose widespread risk to native wildlife, industry and Australia’s way of life.
Rifas have now spread to more than 700,000 hectares (1.73m acres) in the Brisbane region and outlier detections have in the past year been found in Oakey, the Sunshine Coast and northern NSW.
A detection in Wardell, about 70km south of the Queensland-NSW border, was blamed on landscaping supplies brought into NSW for reconstruction efforts after 2022 flood events.
Pianta said that an urgent increase in Rifa suppression was needed.
“Fire ants are one of the world’s worst super pests and their unchecked spread will result in economic damage greater than that caused by cane toads, rabbits, feral cats and foxes combined,” he said.
“We call on Peter Dutton and Anthony Albanese to commit to an urgent fire ant surge and long-term funding.
“Fire ants will spread to all parts of Australia if eradication fails,” he said.
