The world's largest single eradication of yellow crazy ants is being celebrated in Queensland, in a major victory over the acid-spitting threat.
More than 360 hectares near Cairns in the far north are now free of the ants which are among the world's worst invasive species.
"It is a huge win for nature and a massive relief for those who live and work in the affected areas," Senator Nita Green said.
Authorities said the eradication area included 615 lots in Bentley Park, the greatest number of residential properties to be declared free of the invader in one period.
The yellow crazy ant poses a major threat to biodiversity in the Wet Tropics World Heritage area between Townsville and Cooktown.
They can form huge super colonies, with worker ant densities reaching up to 20 million per hectare.
The ants - named for their erratic, "crazy" moments when disturbed - feed on insects which disrupts ecosystem health.
They also kill native animals, squirting acid into their eyes which blinds them and leaves them to starve to death.
More than 450ha are now free of the ants under a $6 million-per-year eradication program funded by the federal and Queensland governments which began in 2013.
"The eradication of yellow crazy Ants in an area four times the size of the previous global record is testament to what can be achieved when governments and community work together," state Environment Minister Leanne Linard said.
About 2300ha across 46 separate infestations in the far north World Heritage area are being managed by the Wet Tropics Management Authority.
More sites are expected to be declared eradicated soon, authorities said.
"Declaring an area free of yellow crazy ants is no easy feat. But the hard work of the Wet Tropics Management Authority, cane farmers, residents and community groups is definitely paying off," Ms Green said.
The yellow crazy ant was discovered in Cairns in 2001 and is among the world's 100 worst invasive species.
'Yellow crazy ants ...can turn our rainforest silent by attacking other insects, birdlife and small wildlife," Invasive Species Council's Reece Pianta said.
"They disrupt food chains and impact agriculture and residential areas.
"The effort to eradicate them from the Wet Tropics World Heritage area is a model ant eradication response taking place in an environmentally sensitive location."
