The prettiest pollinators: A guide to rare and common butterflies of New Zealand
New Zealand is an extraordinary place to study, collect and photograph butterflies. We have an array of them living in a stunning landscape that is both challenging and rewarding to explore. Right now, we recognise 62 butterfly species here, of which 46 are found nowhere else. This figure epitomises both the isolation and fascinating natural history of our South Pacific nation.
New Zealand is a geologically complex land mass, uplifted high and spanning subtropical to cool temperate climatic zones. Our plants are as diverse as the landscape, with different ecosystems along our long coastline, inland plains and hills, and clothing its highest peaks. Here inland salt pans sit comfortably beside short tussock grasslands, nutrient-poor ultramafic hills with alpine shrubland, glaciers within ancient podocarp forests and geysers and boiling mud pools amid rainforest.
Every year our research into New Zealand's butterflies reveals more diversity and interesting relationships. Only a few years ago fewer than 25 butterfly species in New Zealand were listed in all entomological books.
Some of the new additions are "lost" species - such as the copper butterfly that William Fereday, the 19th century "butterfly man", described from Mount Hutt as Lycaena tama, which was forgotten until the 1990s. An expedition discovered that it was still flourishing in its alpine habitat. New additions include wind-blown species from across the Tasman such as Delias nigrina (2010), accidental introductions such as the large white (Pieris brassicae, 2010) and deliberate introductions for biological control of weeds such as the white admiral butterfly (Limenitis glorifica, 2013). The search never ends, and the Moths and Butterflies of New Zealand Trust is always interested to receive images or specimens of anything unusual.
New Zealand's special species
What is unusual about New Zealand's endemic butterflies is that all 46 species belong to only two of the five butterfly families.
For pierids we have to rely on four blow-ins and accidental introductions, while the accidental introductions of two swallowtails Papilio xuthus (1996) and Papilio polytes (2015) remind us about this stunning family of butterflies. The stout-bodied skippers are so far completely lacking here - surprising, when you consider that Fiji has four species and Australia, 122.
But those groups we do have show amazing diversity in colour, pattern, form and ability to adapt to diverse habitats. One of these groups is our fabulous coppers, four of which are confined to the North Island and 22 in the South Island. All can be abundant on sunny days around the larval host plants of our five native species of muehlenbeckia.
Coppers are a genus of small orange butterflies found on every continent except South America and Australia, but it's here in New Zealand where they are most diverse, and we have just begun genetic research to unravel the species' richness and relationships of this group.
There is anecdotal evidence that many of our butterfly species are becoming less common or even disappearing from some areas. This trend probably started with human settlement but has been exacerbated by landscape-wide changes, from extensive stock grazing of semi-natural grasslands in the South Island to dairy conversions in recent years. Butterflies can often tolerate stock grazing but wholesale changes such as cultivation, the replacement of semi-natural vegetation cover and irrigation will quickly eliminate them. The result is that many of our low-altitude butterfly species are now confined to gullies and steep hillside refuges.
One butterfly, the elegant forest ringlet Dodonidia helmsi, has experienced a major decline in both numbers and distribution. It was once found in parts of greater Auckland and Wellington. Now it is long gone from those cities, probably as a result of introduced vespid wasps eating its larvae on various sedges. The butterfly is now only known in areas above 700m and even there populations are local and rare. This is our only true forest butterfly, at home in forest interiors as well as sunbathing on the foliage of forest-edge trees. The elongated green larvae feed on various tall sedges in the genus Gahnia.
Three delightful blue butterflies are all locally common, with a subspecies of the common blue (Zizina otis labradus) now ubiquitous in lowland grasslands south to North Canterbury and the South Island's West Coast. It was probably introduced by some unknown mechanism or possibly self-introduced, but has displaced our endemic southern blue (Zizina oxleyi), which is now common only in Otago and Canterbury.
Small populations of the southern blue can still be found within the wide distribution of the common blue in the North Island, but their future is unclear. The green slug-like larvae of both blues have adapted to feeding on clovers so they are in no danger of extinction. The natural host plant of our southern blue are the prostrate native brooms, such as Carmichaelia corrugata. But these plants have all seen their range get smaller or even extinct locally, so it is fortuitous that the southern blue's larvae can now survive on an introduced host plant.
Since 1965 the long-tailed blue (Lampides boeticus) has been spreading slowly and is now found widely in the north of the South Island and even in the North Island, particularly around the coastline. This attractive species has one of the largest ranges worldwide of any butterfly. Here its larvae feed in the flowers of introduced gorse and other woody legumes. Gorse is a serious problem weed in many parts of New Zealand, of course, so the butterfly is providing some serendipitous biological control!
We share 12 of our butterflies with warmers parts of Australia, from where at least nine are regular blow-ins - arriving here passively on certain weather fronts. They get picked up by large weather systems while migrating within Australia and then get dumped on random parts of New Zealand, particularly western coastal areas. But these regular migrants such as the Australasian painted lady, meadow argus, lesser wanderer, blue moon and the rarer blue tiger butterflies cannot survive our cool winters. They all attempt to breed here and some, such as the painted lady, have produced a New Zealand generation but their populations do not persist. Others such as the yellow admiral, common blue and long-tailed blue have survived and are now a common sight in many places.
One globe-trotting butterfly, the aptly named monarch (Danaus plexippus) is the star among our butterflies these days. Self-introduced over the past 175 or so years following an island-hopping journey from North America, it now delights us in our suburban gardens, overwinters in huge numbers in our parks and is probably the indigenous butterfly that is most well-known to New Zealanders. Schoolchildren rear its caterpillars on swan plants and gardeners grow this plant to attract it to their gardens.
The next step is to convince gardeners that tree nettle (Urtica ferox) and other nettles could also be an asset in thier gardens, in order to nurture the stunning red admiral butterfly and more widespread yellow admiral.
New Zealand hosts three admirals, more than any other area worldwide. On the far-flung Chatham Island group lives the Chatham Island admiral (Vanessa ida), and we share the yellow admiral (Vanessa itea) with eastern Australia - apparently naturally. The New Zealand red admiral (Vanessa gonerilla), meanwhile, is found nationwide, even breeding on an alpine nettle in the South Island's alpine zone. These are all gorgeous and enticing butterflies, with a friendly habit of sunbathing on our house walls, garden foliage and garage doors.
Brian and Hamish Patrick's Butterflies of the South Pacific is published by Otago University Press.
Get acquainted with more pollinators in the photo galleries below.
- NZ Gardener