NZ: Intensive effort to beat pest butterfly breeding
Great white butterflyeradication programme field staff, numbering around 20 at atime, carried out around 5200 garden searches in Aprillooking for the butterfly’s caterpillars and eggs. Theescalated search effort will be kept up during May.
Department of Conservation Motueka Area ManagerMartin Rodd said the success of the DOC-led programme toeradicate the great white butterfly in Nelson Tasman hingedon knocking back this Autumn butterfly breeding spurt withthe help of local residents.
‘The number offinds of great white caterpillars and eggs was well up inApril from 88 in March. We are finding more in part becausewe have more field staff searching and also because thereare more infestations with this breeding surge.
‘Our field teams can’t get everywhere so weare counting on local people looking for clusters of greatwhite butterfly caterpillars and eggs on garden plants andreporting any found to the Ministry for Primary Industries(MPI) hotline 0800 80 99 66.
‘Public reportsenable us to remove the eggs and caterpillars before theybecome butterflies and breed and multiply. Femalebutterflies can lay as many as 750 eggs so we have to get infirst and prevent that if we can.
‘In Aprilmostly eggs and tiny young caterpillars were found. Now thecaterpillars are larger and easier for householders to spotwhich is leading to more calls coming in reporting thesewhich we are very glad to get.
‘These largercaterpillars are speckled black and greyish-green with threeyellow lines along their bodies. Fully grown caterpillarsare around 50 mm in length and have lots of palehairs.
‘If we are going to have a chance ofsuccess, we need people all over the Nelson Tasman region tobe looking out for eggs and caterpillars on thebutterfly’s favoured plants which include brassicavegetables and nasturtium.
‘Although thebutterfly is mostly in Nelson City, with some finds also inRichmond, the butterfly could fly out to new areas. Alsoeggs and caterpillars could be moved into new locations onbrassica vegetables or plants people havebought.
‘Last week three Australian pest expertshosted by their Lincoln University colleagues viewed ouroperation and said that we are on the right track which hasbeen really encouraging to hear.’
There havebeen around 640 great white butterfly infestations foundsince the pest butterfly was first discovered in a NelsonCity garden in 2010.
The DOC-led multi-agencyprogramme to eradicate the butterfly is planned to run overthree years and aims to stop the major pest becomingwidespread in New Zealand. The species poses a seriousthreat to native cresses and home and commercial brassicacrops. The butterfly’s mob-feeding caterpillars canskeletonise plants.
Thehelp of Nelson Tasman residents is essential to eradicatingthe great white butterfly:
· Householders are asked to lookfor caterpillars and eggs clustered on the butterfly’sfavoured plants, including nasturtium, honesty and brassicavegetables such as broccoli, cabbage, cauliflower, bok choy,kale and brussel sprouts. They may also be found onrocket. Any found should be reported to the MPI hotline 080080 99 66.
· The young caterpillars are tiny andyellowish with a shiny black head. The yellow eggs are alsotiny and closely-packed in groups of 30 to100.
· People are asked to help killbutterflies – it sounds harsh but is needed to beat thebutterfly pest.
· Patches of overgrownnasturtium, a butterfly breeding favourite, are beingcleared. DOC is asking people to remove or cut backnasturtium. If people don’t want to remove nasturtiumplants they are asked to keep checking them for caterpillarsand eggs and report any found.
· People areasked to report patches of wild and unmanaged nasturtium toDOC’s Nelson office, ph (03) 546 9335 or email [email protected].