New Zealand’s Department of Conservation is urging all home gardeners in the highly productive Motueka (Nelson) area to look out for great white butterfly infestations in their gardens, and clear nasturtium patches.
By stopping the butterfly caterpillars from laying or hatching, the Department hopes to control this serious pest. Female butterflies can lay up to 750 eggs. There have been around 640 great white butterfly infestations found since the pest butterfly was first discovered in a Nelson City garden in 2010. It is a serious threat to home and commercial brassica crops as well as native NZ cress plants.
· Householders are asked to look for caterpillars and eggs clustered on the butterfly’s favoured plants, including nasturtium, honesty and brassica vegetables such as broccoli, cabbage, cauliflower, bok choy, kale and brussel sprouts. They may also be found on rocket. Any found should be reported to the MPI hotline 0800 80 99 66.
· The young caterpillars are tiny and yellowish with a shiny black head. The yellow eggs are also tiny and closely-packed in groups of 30 to 100.
· People are asked to help kill butterflies – it sounds harsh but is needed to beat the butterfly pest.
· Patches of overgrown nasturtium, a butterfly breeding favourite, are being cleared. DOC is asking people to remove or cut back nasturtium. If people don’t want to remove nasturtium plants they are asked to keep checking them for caterpillars and eggs and report any found.
· People are asked to report patches of wild and unmanaged nasturtium to DOC’s Nelson office, ph (03) 546 9335 or email firstname.lastname@example.org .