The Department of Conservation (DOC) says it has driven Nelson Tasman’s pest great white butterfly population into a state of decline but it needs the public’s help to drive it to extinction.
DOC is asking Nelson Tasman residents to kill as many white butterflies as they can this spring.
Great White Butterfly Project acting manager Tom Belton said spring was a key season for the great white butterfly eradication programme as the whole butterfly population would emerge from pupae together.
“At other times of the year, particularly summer and winter, a significant percentage of the population is in pupae and are hard to detect. Therefore, what emerges in spring provides a good measure of population status.
“It is also the time of year when our eradication programme and the Nelson Tasman public can have the greatest effect because surviving great white butterflies will go on to breed. It is the time of year with the maximum concentration of adult butterflies.
“The numbers of great white butterfly detected by the project’s field team has dropped by more than 50% between autumn this year and last year; this is with a considerably larger search effort, doubling the staff in the field.
“This is great news for the eradication project and for Nelson Tasman but we still need the Nelson Tasman public’s support in achieving our goal of ridding the region and country of this pest altogether.”
It can be difficult to tell the great white butterfly and the small white butterfly apart so people should kill any white butterflies they see as they are both garden pests.
Ranger Graeme Helleur catches a butterfly
If people are confident they have killed a great white butterfly they are asked to ring the Ministry for Primary Industries (MPI) Exotic Pest and Disease hotline 0800 80 99 66 so DOC can identify the butterfly. Information on where butterflies are being killed is critical for the success of the project.
Each female great white butterfly can lay up to 750 eggs, so killing even one makes a big difference. The public can use nets or racquets or whatever else they can find useful to swat the white butterflies.
Last year spring butterfly emergence from pupae commenced in the last week of August and butterflies were frequently captured throughout September. The eradication team is asking the public to keep a lookout for any white butterflies from about mid-August, and to kill any that they can.
The eradication team is also asking the public to keep a look out for and report any great white butterfly eggs and caterpillars to the MPI hotline. These will be found in September and October after the butterflies emerge.
Plans for the great white butterfly eradication team this season include the continued search of properties from Richmond to Wakapuaka with a team of up to 35 rangers a day. During the peak of the breeding season teams may need to visit properties in high risk areas every three weeks.
Tom Belton said continued public support has been great and remains critical for the success of the project.
“Our great white butterfly eradication team is hugely appreciative of the patience of home owners with our garden searches and also residents’ reporting butterfly infestations and killing butterflies.