New reports of ant invaders in Rarangi

22:30, Dec 06 2012
Argentine Ant
Telltale: Argentine ants are honey-brown.

Highly invasive Argentine ants have been found at Rarangi.

Marlborough District Council senior biosecurity officer Dave Grueber said the ants had been found at eight houses near the south end of the residential section of Rarangi Beach.

An "observant" visitor from Nelson had seen the ants at one house in Rarangi and told the owner to contact the council, which had alerted biosecurity staff to the problem, he said.

Argentine ants
Argentine ants are listed by the World Conservation Union as one of the world's 100 worst invasive species

"It's a bit of a blow because that is now the second only place we know of them in Marlborough."

The other is an industrial area in southern Blenheim between State Highway 1 and the railway line, to the Opawa River and along to Stuart St.

The species is known to be well established in Nelson, and it was thought that may be the source of Blenheim's infestation.


Mr Grueber said the council had no idea how the ants got to Rarangi, but they were well-known "hitch-hikers" and spread by "human pathways", hitching rides on things such as potting mix, rubbish, timber, items for recycling, and plants, and establishing in new areas.

Argentine ants are thought to have arrived in Auckland on imported timber during the 1990s.

It was extremely important that people checked items before moving or dumping them, Mr Grueber said.

"We owe it to our community not to spread them any further."

Rarangi Residents' Association president Bev Doole said the properties in the affected area were keen to co-operate with the council in tracking down evidence of the ants.

The community appreciated the biosecurity team's response to carry out the survey and come up with a control programme, she said.

"I haven't had any calls from alarmed residents."

Mr Grueber said the council planned to take control action next month against the ants in Rarangi and the Blenheim industrial area.

The council wanted to keep the ants confined to the areas they were in and to stop them spreading into parks and reserves.

"If they get into our gardens and parks in Marlborough, you won't be taking children there for picnics."

Argentine ants can bite, causing a reaction in some people. They invade homes and other buildings in large numbers, and have been reported to attack nesting birds and kill nestlings.

They have the potential to spread into sensitive ecosystems such as coastal conservation areas.

They out-compete native ants and other invertebrates for food, as well as preying on their eggs, larvae and adults. They also compete for nectar, affecting pollination.

The Marlborough Express