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 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.