Intensive Effort to Beat Pest Butterfly Breeding

Intensive Effort to Beat Pest Butterfly Breeding
 
More than 200 great white butterfly infestations were found and removed in Nelson Tasman last month – more than double those detected in March - as intensive efforts continue to beat an autumn spike in butterfly breeding.
 
Great white butterfly eradication programme field staff, numbering around 20 at a time, carried out around 5200 garden searches in April looking for the butterfly’s caterpillars and eggs. The escalated search effort will be kept up during May.
 
Department of Conservation Motueka Area Manager Martin Rodd said the success of the DOC-led programme to eradicate the great white butterfly in Nelson Tasman hinged on knocking back this autumn butterfly breeding spurt with the help of local residents. 
 
‘The number of finds of great white caterpillars and eggs was well up in April from 88 in March. We are finding more in part because we have more field staff searching and also because there are more infestations with this breeding surge. 
 
‘Our field teams can’t get everywhere so we are counting on local people looking for clusters of great white butterfly caterpillars and eggs on garden plants and reporting any found to the Ministry for Primary Industries (MPI) hotline 0800 80 99 66.
 
‘Public reports enable us to remove the eggs and caterpillars before they become butterflies and breed and multiply. Female butterflies can lay as many as 750 eggs so we have to get in first and prevent that if we can.
 
‘In April mostly eggs and tiny young caterpillars were found. Now the caterpillars are larger and easier for householders to spot which is leading to more calls coming in reporting these which we are very glad to get.
 
‘These larger caterpillars are speckled black and greyish-green with three yellow lines along their bodies. Fully grown caterpillars are around 50 mm in length and have lots of pale hairs.
 
‘If we are going to have a chance of success, we need people all over the Nelson Tasman region to be looking out for eggs and caterpillars on the butterfly’s favoured plants which include brassica vegetables and nasturtium.
 
‘Although the butterfly is mostly in Nelson city, with some finds also in Richmond, the butterfly could fly out to new areas. Also eggs and caterpillars could be moved into new locations on brassica vegetables or plants people have bought.
 
‘Last week three Australian pest experts hosted by their Lincoln University colleagues viewed our operation and said that we are on the right track which has been really encouraging to hear.’
 
There have been around 640 great white butterfly infestations found since the pest butterfly was first discovered in a Nelson city garden in 2010.
 
The DOC-led multi-agency programme to eradicate the butterfly is planned to run over three years and aims to stop the major pest becoming widespread in New Zealand. The species poses a serious threat to native cresses and home and commercial brassica crops. The butterfly’s mob-feeding caterpillars can skeletonise  plants.
 
The help of Nelson Tasman residents is essential to eradicating the great white butterfly:  
 
·  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 motuekaao@doc.govt.nz .

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