- author, Hannah Ritchie
- scroll, From BBC News in Sydney, Australia
Fire ants form veritable floating rafts to navigate the flood waters affecting Australia. Storms have recently devastated the country, helping spread one of the world's most invasive species.
Considered a super pest, the red fire ant (Solenopsis invicta) can cause major ecosystem changes and harm crops by feeding on native plants and animals.
The Invasive Species Council of Australia says the unusual floating raft-forming behavior is evidence that “the population density of fire ants is increasing” in the country.
The government asks communities in the states of Queensland and New South Wales – which are witnessing harsh weather conditions – to be on high alert against these ants as they move and establish “a foothold in new areas.”
Floating swarms of ants have been documented on sugarcane plantations south of Brisbane, where fire ants have overrun about 700,000 hectares of land.
Native to South America, including some parts of Brazil, red fire ants were first discovered in Queensland in 2001 and have been concentrated within the state's borders ever since.
How they got into Australia remains a mystery, but it is thought they likely came from the US in containers.
In November, local authorities reported that several new fire ant nests had spread into New South Wales from the Queensland border for the first time – prompting increased government investment to control the pest.
Fire ants often spread through soil and contaminated materials that people bring to new areas. Some of them have wings and are able to fly several kilometers. They can also travel much farther if they are blown by wind currents.
Australia's unique climate and lack of natural predators make it an “ideal habitat for fire ants,” which can inhabit “the entire continent except the coldest places” if left uncontained, according to biosafety authorities.
One of experts' biggest fears is that these ants will one day enter the Murray and Darling Rivers and, from there, quickly advance into new states and territories.
A three-year colony can contain up to 100,000 ants of this species. A mature queen can lay up to 5,000 eggs per day.
In recent decades, fire ants have spread to the United States, China, Taiwan, Japan and the Philippines, according to the Australian government.
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