Weta a winemaker's bugbear

This native weta, formerly known as the Cape Campbell ground weta, has proven a headache for winemakers in Marlborough's Awatere Valley because of its fond taste for grape vine buds.

It's a conservation conundrum: what to do with a potentially threatened native species that's been making a pest of itself?

The endemic bug, formerly known as the Cape Campbell ground weta, has proven a nuisance for winemakers in Marlborough's Awatere Valley because of its fond taste for grape vine buds.

On warm dark nights, at the time of year when the buds are bursting, the weta crawl out of their burrows in the vineyards and feed on the swelling buds.

Lincoln University researcher Jerry Nboyine, who works in the collaborative Bio-Protection Research Centre, said one year vineyard owners lost a third of their annual yield in a few weeks.

"The buds are also relied upon to produce the following year's yield - so without having any canes to lay down for the next year, it causes a lot of panic."

If they were dealing with a recognised pest, winemakers might combat this threat with pesticide. Mr Nboyine said it wasn't known whether these weta were threatened as their conservation status was unclear.

Mr Nboyine has been working with vineyard owners to find ways of minimising the impact of the insects, which has included tying plastic sleeves around the vine bases to prevent them climbing up to the buds. But that method was expensive, as the plastic tore and soon needed replacing.

"We want to make sure that we prevent vine damage without killing the insects, which is an unusual challenge," he said.

"Early data are showing that simply sowing tasty broad beans between the vine rows can tempt the weta away from the vines.