Yellow crazy ants

Yellow crazy ants, one of the world's worst invasive species, are the target of a management project in north-east Arnhem Land in the Northern Territory.

The Challenge

Managing yellow crazy ants in north-east Arnhem Land in the Northern Territory.

Yellow crazy ants (Anoplolepis gracilipes) are one of the world's worst invasive species. They can form huge super-colonies containing thousands of queens and have worker densities reaching up to 20 million ants per hectare.

Yellow crazy ant queen and worker. © Phil Lester

Yellow crazy ants were first discovered in north-east Arnhem Land in the NT in 1980 and are now known to occur throughout 16,000km2.

The ants pose a major threat to Australia's biodiversity. They can out-compete and displace native invertebrates, which are crucial for ecosystem health.

The impacts of Yellow crazy ants are best known from Christmas Island, where they have been responsible for the death of up to 20 million Red land crabs, causing major changes to the rainforest ecosystem. In Queensland, the ants are contributing to the decline of native species in areas they have invaded.

Yellow crazy ants tend sap-sucking insects, like scale and aphids, making them a serious pest of horticultural crops. They also produce formic acid spray, which can cause skin and eye irritations.

Our Response

The Yellow Crazy Ant Management Project

Since 2003, CSIRO has been working with the Dhimurru Aboriginal Corporation and Rio Tinto on the Yellow Crazy Ant Management Project. The project, which is supported by the Australian Government, aims to develop a management strategy for successful eradication. CSIRO has developed a triple-treatment program which involves specialised ant bait dispersal by helicopter.

The Results

Successful eradications

Yellow crazy ants have been eradicated from 26 locations covering more than 295 hectares on Aboriginal land in the NT.

Research has found that despite the impacts of yellow crazy ants and some potential non-target impacts by baiting, native species recolonise and recover quickly, usually within one to two years.

The Yellow Crazy Ant Management Project has been internationally recognised.

The project was the winner of a prestigious Banksia Award (Biodiversity category) and the gold Banksia Award. The project also won the inaugural Caring for Country Award at the National Aboriginal and Islander Day Observance Committee Awards in 2010 and the Biodiversity Category of the United Nations Association of Australia World Environment Day Awards in 2011.


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