A tiny Irish wasp released in New Zealand to control one of the country's worst pasture pests is resisting attempts to get it established in the Far North.
AgResearch entomologist Pip Gerard, who heads the programme to control clover root weevil, says the wasp has thrived in most North Island districts where it has been released, despite the summer drought.
But Dr Gerard told a plant protection conference IN Paihia on Tuesday that it has failed to establish in Northland for the second successive season.
The weevil, which destroys clover in pasture, has spread through most of the North Island and has also been found at the top of the South Island.
Dr Gerard says it is not known why the Irish wasps seem to snub Northland, but her team will be carrying out research to find out why.
Meanwhile, plans are well under way to distribute more wasps to farmers who have weevils infesting their pasture.