The ants are common in the North Island and have been found in a few South Island urban areas, including Dunedin.
They do not bite or sting or cause structural damage to homes, but Environment Southland biosecurity officer Paula Hatton said that unlike native New Zealand ants, which lived outside, white-footed ants foraged en masse inside homes for water and anything sweet.
They could also make their nests in the walls of homes.
''They are a nuisance ... and very difficult to get rid of.''
The first confirmed population in Southland was in Gladstone, Invercargill, in 2009, she said.
The ants found in the Taramea Bay Rd area of Riverton were the only confirmed sighting since.
Anyone who thought they might have white-footed ants should collect a few in a lidded container and take them to the council office in north Invercargill.
If there was a positive identification, council staff would visit the house and begin eradication by baiting, she said.
- allison.beckham@alliedpress.co.nz
