Jacqui Knight, secretary of the Monarch Butterfly New Zealand Trust, is puzzled.

'Where are monarch butterflies overwintering?” she asks.

'We have received reports of new locations this year but nothing from other parts of New Zealand. And in some parts of the country females are still laying eggs and caterpillars munching away.”

Historically, every year at the end of the summer, monarch butterflies go into diapause. This means that although they're sexually mature they won't breed until the spring. Instead, they accumulate in trees, gathering on the sunny or sheltered side in large numbers, waiting out the winter, only coming out on sunny days to top up their nectar reserves.

"By staying still in the treetops during the cold or wet weather they conserve their energy. But when they get warm enough to fly they will go looking for nectar sources in gardens. People with old-fashioned camellias and bottlebrushes will tell you monarchs visit during the warm winter days," says Jacqui.

However, this year there have been no sightings recorded from some parts of the country.

'There is something truly magical about seeing large numbers of monarchs in the treetops,” she says. 'It makes you reflect on the environment, about biodiversity, and gives you hope for the future. If these insects have been surviving for millions of years, there's hope for us all.”

Most reports have come from various parts of Auckland, Whakatane, Gisborne, Hamilton, Levin, Martinborough, Clive, and Christchurch.

'There used to be many reports from Christchurch, Timaru and Oamaru,” she says. 'But not this year. We encourage people to post reports on the special webpage for this purpose www.mb.org.nz so we can study what is happening with these beautiful butterflies."