Great white butterfly

The great white butterfly poses a major economic and environmental threat. This introduced pest is a threat to commercial and home brassica crops, and to native cresses.

Great white butterfly caterpillars on honesty plant.
Great white butterfly caterpillars on honesty plant

It was first found in New Zealand in a Nelson city garden in 2010 and has since been spreading in Nelson Tasman.

DOC is leading a multi-agency attempt to eradicate the great white butterfly to stop it becoming a major pest in New Zealand. The help of Nelson Tasman residents is vital to achieving eradication, including looking for and reporting great white butterfly caterpillars and eggs.

The great white butterfly has been declared an unwanted organism in New Zealand under the Biosecurity Act 1993.

The great white butterfly could become a serious pest in New Zealand if its spread is not stopped.

Description

You can help

Find out about DOC's work and how you can help to eradicate the butterfly.

Activities you can get involved with:

  • Join a school hunt: Primary school classes can join the great white butterfly school hunt and become super heroes for conservation.
  • Garden hunt and prize draw: Help search for great white butterfly caterpillars and eggs this spring and be in the prize draw to win a fantastic family trip for five to Hanmer Springs.
  • Join the family fun day on Sunday 28 September 2014 - the great white butterfly eradication team wants to say thank you for your continued support.

Why it's a pest

The great white butterfly (Pieris brassicae) has been declared an unwanted organism in New Zealand under the Biosecurity Act 1993. It is a significant pest of brassica crops in numerous countries across Europe and western Asia. Its caterpillars feed voraciously, reducing host plants to a skeleton.

The butterfly can fly long distances – sometimes hundreds of kilometres – so will spread further through New Zealand if not stopped.

Risk to native and cultivated brassica plants

Great white butterfly caterpillars feed hungrily.
Great white butterfly caterpillars feed hungrily

The great white butterfly could have serious consequences for the survival of many of our native cress species. New Zealand has around 79 native cress species, 57 of which are at risk of extinction.

It is far more destructive to plants than the common small white butterfly. Great white butterfly catterpillars feed in groups, rapidly reducing plants to a skeleton.

As well as being a menace in home gardens, the great white butterfly poses a threat to commercial brassica vegetable crops - it could cost the country millions of dollars to protect these from the pest butterfly if it became widespread in New Zealand.

Brassica crops are important in New Zealand, with about 4000 hectares of vegetable brassicas grown, worth approximately $80 million per year, and a rapid expansion in production of forage brassicas. Forage brassicas are grown mainly for dairy production with around 300,000 hectares now grown annually, mostly in Canterbury.

Cultivated brassicas include cabbage, broccoli, cauliflower, rape, swedes, Brussel sprouts and turnips.

Great white butterfly male. Photo copyright: www.improvedimage.co.uk.
Male great white buttefly