The Yellow Crazy Ant (YCA) (Anoplolepis gracilipes) is ranked among the top 100 worst invasive species in the world by the UN Invasive Species Specialist Group. The Ant is believed to have made its way from South-East Asia to the Gove Peninsula, about 600 kilometres east of Darwin, during World War II.

This ant represents a very serious environmental and economic threat to northern Australia for many reasons. They occur in extremely high numbers and eliminate many native animal species in areas where they are found. They also cause outbreaks of sap-sucking insects, which can kill plants. These ants can also be a serious pest around homes.

“The Yellow Crazy Ant is one of the world’s worst ant pests and is found within Arnhem Land in the Northern Territory. The ants form super colonies making them a serious threat to agriculture and to the natural environment,” CSIRO ecologist Dr Ben Hoffmann said.

The Corporation’s Executive Officer, Steve Roeger, says the ants are an environmental nightmare. "They move in, they take over, they kill all the invertebrates and ultimately you end up with nothing but Yellow Crazy Ants," he said.

Dhimurru Aboriginal Corporation took the lead role in a collaborative attempt of YCA eradication in 2004.

Within five years, this program has declared YCA eradicated from 21 sites covering 246 ha. This is twice as many eradications, covering five times more area than all ant eradications published globally for the past 100 years. The ant is also believed to be eradicated from another 14 sites that await assessment. In addition, ecological monitoring at 17 sites has quantified full ecological recovery within 12 months. In total, 8127 locations have been assessed through the region for the presence/absence of YCA, 238,454 assessments have been made to accurately map 35 infestations, and an additional 221,624 tuna lures have been used to assess YCA eradication.

Treatment involves the delivery of a bait designed specifically for Yellow Crazy Ant, from a motorised hopper underslung from the Laynhapuy helicopter. This method has proven to be highly successful.

The bait used has a very low toxicity which does not affect birds, mammals or reptiles. Few other ants and other invertebrates are known to consume the toxic bait. In most cases, Yellow Crazy Ant have killed most of the fauna within infested areas. Monitoring of non-target impacts is also a focus of the eradication project.

Large signs have been erected near many of the infestations. The signs are there to inform people of the presence of the ants, not to prevent people from accessing the affected areas. Please be careful not to spread the ants if your travels place you within one of these areas.

The spread of Yellow Crazy Ants requires accidental transport, so it is important to ensure that this does not happen. You can help by being extremely vigilant when transporting anything, especially pot plants, house goods and machinery to ensure that they are not spread to new locations. They readily nest in all kinds of material, from potting mix, to swags and gaps in vehicles, making it very easy for them to be accidentally transported by people.

Everybody is also encouraged to report any suspected sightings of Yellow Crazy Ant. The ant is medium-sized (about 3-4 mm long), yellow, fast-moving ant that is quite distinct from most native ant species. However it can be easily confused with the native Yellow Tyrant Ant that is similar in size and colour. The main distinguishing features of Yellow Crazy Ants are: very long antennae and legs, no smell when the ant is crushed, they do not bite when disturbed, and the nests have no mounds of soil.

“These ants have the capacity to spread from Broome in Western Australia across to Queensland. We have a responsibility to attack this problem as urgently as we can before they get the opportunity to spread,” said Dhimurru Senior Ranger Daryl Lacey.

The project is set to continue with annual funding from Rio-Tinto Alcan and in-kind contributions from other key stakeholders. The goal is to achieve regional containment within three years thereby negating the need for continual ongoing work.

Dhimurru would like to acknowledge the keen support shown for this program over the years with key players including, Rio Tinto Alcan Gove, CSIRO, traditional land owners, the Northern Territory Government, the Commonwealth Government, Conservation Volunteers Australia, the Indigenous Land Corporation, and the Aboriginal Benefits Account, as well as Yirrkala Dhanbul Assoc., Nhulunbuy Corp., Northern Land Council.

If you think you have seen this ant, or would like further information, please ring the Dhimurru Office on 8987 3992. Information and identification sheets are also available at the Dhimurru office.