Skip to main contentSkip to navigationSkip to navigation
A fire ant
Fire ants can devastate local wildlife and make backyards and parks unusable, says Andrew Cox, the chief executive of the Invasive Species Council. Photograph: Department of primary industries/AAP
Fire ants can devastate local wildlife and make backyards and parks unusable, says Andrew Cox, the chief executive of the Invasive Species Council. Photograph: Department of primary industries/AAP

The ants go rafting: invasive fire ants take to Australian flood waters to colonise new areas

This article is more than 1 year old

Dangerous pests forming floating rafts with their bodies to survive in Queensland after floods

Invasive fire ants have used recent flooding in Queensland to expand their Australian invasion, teaming up and forming floating rafts with their bodies to allow them to survive for weeks at a time.

Eradication officers in Queensland have captured photos of the dangerous ants forming the rafts in flood waters.

It’s one of the pest’s most impressive survival tricks. Thousands of ants lock their bodies tightly together, trapping air bubbles in the process to keep them afloat.

Colonies can survive for weeks this way, with the multi-layered structures strong enough to keep rescued queens and their eggs, larvae and pupae safe and dry. The ants on the bottom also take turns to make sure they don’t drown.

When flood waters eventually subside, the rafts can be deposited in new areas, allowing the species to spread and further threaten ground-dwelling native fauna, agricultural activities and human health.

Dr Ross Wylie is the science leader at the $400m National Fire Ant Eradication Program, tasked with dealing with the foreign invader native to flood-prone parts of South America.

“This rafting is one of the ways fire ants can colonise new areas, and this has been observed in south-east Queensland, including in Purga near Ipswich and around Logan,” he said.

“They can float for weeks until they come to dry land or a place where they can start a nest again.”

Dr Wylie said eradication officers always see an increase in fire ant activity reports after wet weather.

“It is likely that the ants were there before the rain, but as they don’t tend to build their nests up in hot, dry weather, people weren’t aware,” he said.

“We plan for this type of thing and have teams on stand-by to the deal with any infestation that pops up. Alternatively, people can opt to engage a pest manager or purchase fire ant bait from a local retailer and treat their property themselves.”

In this picture from 2017, fire ants in Texas in the US form a raft on water. Photograph: Mike Hixenbaugh/ Houston Chronicle/Reuters

Fire ant nests can appear as dome-shaped mounds or be flat and look like a small patch of disturbed soil. They also lack obvious entry or exit holes.

Andrew Cox, the chief executive of the Invasive Species Council, said there was a big risk recent flooding in Queensland would have resulted in the highly invasive species spreading to new areas.

“Fire ants can devastate local wildlife and render backyards and parks unusable,” he said.

“They have been known to kill pets and have been responsible for over 85 human deaths in the US.

“This underscores the need to overcome the delays in reducing the size of the outbreak and to get the eradication program on track.”

The current fire ant eradication program is funded jointly by federal, state and territory governments.

A recent review of the program found more resources were needed if governments were to successfully eradicate fire ants from Queensland and Australia.

“We’d like to see governments increase investment in this critical program and create an independent authority to run it,” Cox said.

The photo on this article was amended on 14 April 2022. An earlier photograph incorrectly labelled a different ant species as a fire ant.

Most viewed

Most viewed