The Environmental Risk Management Authority (ERMA New Zealand) has received an application to import the beetle from the Auckland Regional Council, on behalf of the Department of Conservation and a group of other regional councils.

“Tradescantia is a real and growing conservation threat in many parts of the country and a well known weed in home gardens,” General Manager New Organisms at ERMA Dr Libby Harrison says.

“Dense mats of it can smother low growing native plants and it is a threat to forest regrowth.”

Beetle larvae feed on the plant’s leaves and in large enough numbers can cause severe damage to the dense mats.

Tradescantia can also be killed with herbicide or physically removed, but neither approach is feasible because of the huge number of sites in New Zealand where it is a problem.

Landcare Research has assessed the safety of the beetle for release and says risk to native plants is negligible as Tradescantia is not related to any New Zealand plants.