Archives For Great white butterfly

By Trish Grant, Communications Advisor, Nelson

The battle against the great white butterfly pest appears to be working with detections dropping by more than fifty percent in autumn this year, compared to autumn last year.

The species is only found in the Nelson/Tasman region and DOC has been leading a programme to eradicate the pest out of concern for the threat it poses to our endangered native cresses. Successful eradication of the butterfly would be a world-first.

Ranger Graeme Helleur holding a butterfly. Photo: Sally Leggett.

Catching butterflies is all in a day’s work for the team

The Nelson eradication team’s drive and determination will be a key factor in achieving that success. An example of that determination was on display recently when four of the team armed with nets chased a darting biggish white butterfly through at least five properties, across the road, and up and down hills, determined not to let it escape their clutches. Finally Ranger Maddie netted it. It proved to be an important catch: a female great white butterfly full of eggs that could have set up a new infestation in an area where butterfly finds had become few.

A female great white butterfly on a leaf.

Female great white butterflies can lay up to 750 eggs

The team are not the only intrepid butterfly catchers. Team members searched gardens in one area for several days looking for a female butterfly suspected to be in the vicinity. It was duly presented to them dead by an elderly woman who in spite of poor eyesight had managed to trap the butterfly with a glass on the wall of her house.

This spring will be a pivotal time when the whole butterfly population emerges together from pupae, giving a good measure of its population status. DOC is working closely with the community to clear this major pest from the region and the country.


Rangers with nets at the ready in a large patch of wild brassicas that will be sprayed

The Nelson DOC team will be holding a great white butterfly family fun day on Sunday 28 September.

By Trish Grant, Communications and Engagement Advisor, Nelson

DOC is renowned for its island pest eradications, now we are leading a pest eradication programme that is focussed on home gardens to wipe out the great white butterfly in Nelson Tasman, which if successful, would be a world first.

The great white butterfly caterpillars.

The caterpillars

The pest butterfly was first found in a Nelson garden in 2010, and has since then been spreading in the city and into nearby Richmond in Tasman. It is a significant pest of brassica plants in numerous parts of the world and is thought to have entered New Zealand as a pupa on an item shipped into Port Nelson.

The aim of the programme is to stop the pest butterfly in its tracks and prevent it spreading to other parts of New Zealand.

With an autumn surge in great white butterfly breeding now underway, around 25 DOC staff are scouring gardens in and around Nelson city searching for the butterfly’s distinctive caterpillars and tiny yellow eggs clustered on host plants. Beating this breeding surge and knocking down the caterpillar numbers is critical to the success of the eradication programme.

The DOC team have initiated a ground-based attempt to eradicate the butterfly in November out of concern at the serious threat it poses to our native cresses; of the 79 species, 57 are at risk of extinction. We need a lot of people on the ground to find and remove all the butterflies, caterpillars and eggs we can to beat the butterfly and stop it becoming a widespread major pest.

The public support has been fantastic. The people of Nelson Tasman have been out looking for and reporting eggs and caterpillars and have been heeding the call to help kill the butterflies to stop them laying eggs.

The programme is due to continue until 2017 and if it succeeds, it will be the first ground-based eradication of the great white butterfly achieved in the world.