Fire ants have been spotted “rafting” in Queensland floodwaters, sparking fears the behaviour could accelerate the spread of the deadly pest across Australia – with devastating outcomes for the livestock industry.
Australia had contained fire ants in south-east Queensland for 20 years, until last November when six nests were reported 13km south of the Queensland border at South Murwillumbah and another was found on the border at the Currumbin Valley last month.
With news that fire ants can travel in “rafts” in floodwaters for weeks at a time, it’s feared that they could get into the nation's Murray Darling River system and then move rapidly into new states and territories.
Invasive Species Council Advocacy Manager Reece Pianta said fire ants were expected to have a $2 billion per year impact on Australia’s economy if they get out of control.
“They will devastate wildlife, cut agricultural output by up to 40% and may cause over 100,000 extra medical appointments each year,” Mr Pianta said.
Fire ants reduce beef production by 40%, and it’s estimated the beef industry in Queensland alone would lose $127 million in production annually if they were to spread across the state.
“They are three times more venomous than any other stinging insects in Australia,” Mr Pianta said.
“They eat almost anything and can sting en masse and swarm their pray, which can be lethal to young livestock.”
They can also attack mature animals via soft tissue such as the eyes, mouth, nose and ears, crippling animals to the point the only human thing to do is to euthanise.
The cattle industry is particularly vulnerable, with Mr Pianta saying that evidence from Texas vets is that 75% of all animals treated for fire ant attacks were cattle.
On top of loss of livestock and diminished growth rates, farming land is also lost to production while it is treated, the nearby land baited, and paddocks cleared of livestock for their safety.
Fire ants are spreading across Australia at a rate of 5km a year.
Fire ants are one of the world’s worst invasive species, which various Australian governments have tried to eradicate or contain since they were introduced in the late 1990s in freight from the US.
These programs have not been enough, with fire ants still spreading about 5km each year.
However, they are slowing the spread compared to countries who have given up on controlling the pests.
In the US, fire ants are spreading 45km a year and in China the annual spread is 80km each year.
The situation has escalated to the point that some US farmers are abandoning land because it isn’t economically viable to farm livestock in their area anymore.
Fire ants live in distinctive mounds of loose, crumbly or fluffy-looking soil.
Fire ants are dark reddish-brown with a darker black-brown abdomen and range in size from two to six millimetres long.
Their nests are distinctive mounds of loose, crumbly or fluffy-looking soil with a honeycomb appearance, up to 40cm high, with no obvious entrance holes.
Fire ants like open grassy areas with lots of sunlight, particularly where soil is disturbed, making Australian farms prime locations for them.
They usually spread in spring, with mass spawning events, called nuptial flights, in which hundreds or thousands of queens fly up to 30km, in favourable conditions, to create new colonies.
They can also stowaway in freight or soil.
Fire ants rafting during this month's Gold Coast floods.
Mr Pianta explained that during floods fire ants grip using their legs, forming a rough ball, with the queen in the middle, and slowly rotate taking turns being on top, so most ants survive the rafting journey and don't drown.
The complex manoeuvre has been recorded at cane farms south of Brisbane during recent flooding events.
“Fire ants are more active before or after rainfall and can form large floating rafts which move with water currents to establish footholds in new areas,” he said.
“The good news is that it will be easier to spot fire ants and their nests at this time.
“We are therefore calling on the community to be on the lookout for fire ants. It’s really easy to do your part. Just take a picture of any suspicious ants and report it.
“Don’t worry if you’re not sure what type of ant it is, every picture that is sent in will be vital information for the eradication program.”
He also reminded people that fire ants are dangerous.
“Don’t put yourself, clothing or belongings in direct contact with ants or their nests,” Mr Pianta said.
Fire ants pose a risk to all states and territories of Australia. Graphic: Invasive Species Council
The Invasive Species Council has welcomed a recent $70 million four-year commitment from Victoria towards the national fire ant eradication program.
“This new fire ant funding from Victoria, when combined with the recent funding boosts from the federal, NSW, Queensland, ACT and NT governments, means eradication is still possible,” Mr Pianta said.
“Fire ants are one of the world’s worst super pests and, if they are allowed to spread across the continent, their economic impact will be greater than cane toads, rabbits, feral cats and foxes combined.
“However, there is still a $56 million funding shortfall for the national program as South Australia, Western Australia and Tasmania have not yet committed their share of funds.
“Fire ants are a national problem for Australia – money spent now saves billions down the track.”