Yellow crazy ants — a highly invasive exotic pest that can build super colonies and devastate local fauna which were first detected near Yamba in 2004 — have been eradicated from NSW.

Minister for Primary Industries Ian Macdonald said: “An infestation of yellow crazy ants has been nipped in the bud at Goodwood Island wharf on the Clarence River near Yamba — the only known infection site in NSW.

The CSIRO says the Yellow Crazy Ant is probably native to tropical Africa, but has been spread world-wide by people.

The ant has been on Christmas Island for the past 70 years and has had an extremely destructive impact on the native fauna.

The Yellow Crazy Ant has now been found in numerous locations within eastern Arnhem Land. It is most abundant around human settlements, along creeks and in shaded areas.

Mr Macdonald said: “A rapid early response by NSW Department of Primary Industries regulatory officers and two years of close surveillance without detecting the pest has enabled this pest-free declaration.

“This highly destructive ant can spread very quickly, causing dramatic consequences for the ecosystem it is invading.

“They can attack and kill creatures like crabs and reptiles, using formic acid to overpower and destroy their prey very quickly.

“They form super colonies with several queens and once a super colony is established, it can expand rapidly, in some cases doubling in size in 12 months.”

Mr Macdonald said crazy ants are recognised by their pale yellow body colour, unusually long legs and antennae.

“The name ‘crazy ant’ is derived from their frantic movements and frequent changes in direction, especially when disturbed,” he said.

Mr Macdonald said yellow crazy ants have been a particular problem on Christmas Island, rapidly depleting populations of the iconic red land crabs, which are vital to the island’s biodiversity.

He said yellow crazy ants were last detected at Goodwood Island wharf on 31 January 2006, in a pile of discarded telegraph poles.

“A licensed pest exterminator was contracted to work with the port authority to treat the poles and the ground beneath them to kill all ants in their exposed nests,” he said.

“The poles were then piled on site and burnt.

“Two years of nil detection since has met the benchmark for claiming the eradication of this exotic pest.

“The final detailed surveillance survey of the wharf area was undertaken in March 2008 by NSW DPI regulatory staff.

“This survey involved placing food lures at intervals of five metres, general observation, collecting ants for identification and lifting and inspecting an old stockpile of logs.

“No yellow crazy ants were detected.”