The Department of Conservation says no great white butterfly infestations have been found so far over autumn but it is asking Nelson residents to keep a lookout for the pest over winter.
DOC Great White Butterfly Project Manager Michael Shepherd said no great white butterfly detections for nearly five months, since 16 December, didn’t necessarily mean all the butterflies had been wiped out.
“Autumn is a peak time for butterfly breeding so not finding any is promising but there could still be butterflies around that have escaped detection. Our butterfly eradication programme continues to ensure we eliminate the entire population.”
Mr Shepherd said butterfly activity reduced during winter so DOC is scaling down its garden searches. Searches would be stepped up again from late winter when butterfly activity and breeding begin to pick up again.
“We’re asking the public to still keep a look out over winter as some caterpillars and eggs may turn up on winter brassica vegetable crops such as cabbages, broccoli, kale and cauliflowers. Some caterpillars stay dormant as pupae through winter and the great white butterfly’s greyish-white or pale green pupae might be found on fences and other structures.”
Anyone finding great white butterflies, their eggs, caterpillars or pupae, is asked to report it by calling the Ministry for Primary Industries hotline on 0800 80 99 66. DOC staff will then respond.
DOC is also asking gardeners to consider planting winter cover crops that don’t attract the pest butterfly. Many people plant mustard, but this is a brassica and great white butterfly host plant. DOC suggests instead planting cereal crops such as rye, oats and barley instead. Other alternatives are plants from the pea family such as lucerne and broad beans.