Wet weather in northern NSW and south east Queensland has boosted activity among one of the world's most invasive species.
Fire ants are on the move on land and water, thanks to raft-building abilities, according to the Invasive Species Council.
"The wet weather has led to fire ants being back on the march and they're also travelling in the floodwaters," the council's Reece Pianta said.
"Talking to cane farmers on the northern Gold Coast, they've seen fire ant rafts coming with the floodwaters as a result of the wild weather."
The increased ant activity follows heavy summer rainfall across northern NSW and south-eastern Queensland, with the deadly pest most active at times of rain.
Ants can make rafts by locking together and forming a ball with the queen in the middle, before detaching from the bank and moving with the water.
"It's a bit alarming that they're reaching densities where they can form rafts and are potentially spreading to new locations," Mr Pianta said.
Fire ants are found from Caboolture in Queensland and south to the NSW border.
The first NSW detection was made in November when six nests were reported by a property owner in South Murwillumbah, 13km south of the Queensland border.
The NSW government said the nests had been destroyed by direct injection, with the area monitored.
"The NSW government is working hard after eradicating the fire ant nests found in South Murwillumbah in late November last year," NSW Minister for Agriculture Tara Moriarty said.
She said no further detections have been made in NSW.
The South American pest arrived in Australia in the late 1990s in freight from the United States and was found in 2001.
A senate inquiry will hold public hearings in March to examine Australia's efforts to eradicate the pest amid claims of chronic underfunding.
It's estimated the economic impact of fire ants spreading across the country would be between $1.25 billion and $2 billion annually.
Federal Agriculture Minister Murray Watt has warned the ants could do more damage to agriculture and the environment than all of the worst invasive pests combined.
So far $750 million has been spent trying to terminate the pest in Australia, through the national fire ant program, with $1.2 billion committed.
The invasive species council has urged everyone in the southern Queensland and northern NSW areas to stay vigilant.
"If they see them, (fire ants) go to fire ants.org.au and report them," Mr Pianta said.
