Butterflies and moths are members of the insect order Lepidoptera (from the Greek meaning ‘scaly wings’). Globally, Lepidoptera is the group with the most insect species associated with flowering plants. There are more than 350,000 known species, 20,000 of which are butterflies.
Like other large insect orders, the Lepidoptera group contains members with a variety of forms, behaviours and ecologies. They are grouped into about 39 superfamilies worldwide, of which 16 are represented in New Zealand. Of 120 families, 35 occur naturally in New Zealand. Two are butterflies and the rest are moths.
‘Moth’ and ‘butterfly’ are common names given to insects of the order Lepidoptera. There is no strong scientific basis for these terms. There is an evolutionary continuum from the most ancient moth group to the most sophisticated butterfly group. Some moths are more closely related to butterflies than to other moths.
There are some general differences between moths and butterflies. Moths usually hold their wings flat while resting, have feathery antennae, and are active at night. Butterflies tend to be more brightly coloured, have clubbed antennae, hold their wings erect while at rest, and are active by day. But there are exceptions to these generalisations. Many New Zealand moths fly during the day or at dusk. The black mountain ringlet butterfly holds its wings flat while at rest. Some New Zealand butterflies are drab, and most people would call them moths. One sure way to distinguish the two in New Zealand (this does not apply globally) is that all native butterflies have clubbed antennae.
Essentially, however, there is no consistent difference between butterflies and moths. Any superficial differences become exaggerated in a temperate country like New Zealand, where many of the larger, highly developed moth groups (which are more like butterflies) found in warmer countries are missing.
Endemic species are those that are unique to a particular area. New Zealand’s Lepidoptera order displays the world’s highest rate of endemism. The majority (92%) of species are found nowhere else. By comparison, Britain shares its Lepidoptera fauna with mainland Europe, and none of its species are endemic.
New Zealand’s butterflies and moths are distinctive for several reasons. They have:
New Zealand species are significantly different from Australian species.
Lepidoptera is one of the three most species-rich insect orders in New Zealand, and moths and butterflies are relatively well studied. The total number of native species is not accurately known as many new species continue to be discovered, although it is likely to exceed 2,000. Traditionally it has been accepted that New Zealand has about 20 butterfly species. Only 12 have been formally described. Recent research suggests that there may be a further 25 types of copper butterfly, along with new black mountain ringlets and other native species. If this new research proves correct, the total number of butterfly species may be about 70. Of these, 10 are tropical species that are periodically blown over from Queensland, Australia, of which two have become established. An additional four species have been introduced by humans, of which the familiar cabbage white (Pieris rapae) is the most conspicuous.
This rich biodiversity includes the large pūriri moth (Aenetus virescens), which lives in North Island forests and attains a wingspan up to 15 centimetres, and the pinhead-sized, leaf-mining moths of the family Nepticulidae, with wingspans of just 2 millimetres.
An additional 68 moths have been deliberately or accidentally introduced since European settlement, and have established wild populations.
Early entomologists including George Hudson and Alfred Philpott have left a legacy of illustrated books and articles on the country’s moths and butterflies.
New Zealand’s butterflies and moths occupy a wide range of habitats, from rocky coasts to rugged mountains. One still undescribed species lives on ice-free rock faces 3,000 metres high. A few species are common and widespread, but many are rare or live in very small areas. Some have thrived with the arrival of humans, but many more have declined – over 110 species are threatened with extinction.
Of the New Zealand butterflies, two groups (admirals and coppers) are nationally and globally significant for their species richness.
Admirals are found worldwide, and three species occur in New Zealand. Yellow and red admirals are widespread on the mainland, especially at the edges of forests, on farmland, and where there are nettles (Urtica ferox), which the larvae eat and live on.
Butterflies and moths are popular subjects in art and design, adorning company logos, clothing and the exterior of homes nationwide. Many conspicuous species have appeared on postage stamps such as the magpie moth and red admiral. The $100 banknote features the elegant South Island zebra moth.
Chatham Island admirals are confined to those windswept islands.
The number and variety of copper butterflies in New Zealand is unrivalled worldwide. These mainly orange butterflies can be found throughout the country, including the high alpine zones. They have diversified into at least 40 species within four groups. No single species occurs nationwide, and many have very small distributions.
As with most New Zealand Lepidoptera, copper larvae are particular feeders – they eat only Muehlenbeckia of the dock family. This includes the tiny-leaved, ground-hugging M. axillaris and the extensive vines of M. australis, which can stretch 20 metres over the forest-edge canopy. Copper butterflies have their closest relatives in the cloud forests of New Guinea and in the temperate northern hemisphere.
Certain species of boulder copper butterflies are among the world’s smallest, with a wingspan of less than 1 centimetre. The largest New Zealand coppers have a wingspan of up to 3 centimetres.
Butterflies and moths play several important ecological roles:
For an ecosystem to sustain a butterfly or moth species, it must provide the exact requirements for all stages of its life history (egg, larva, pupa and adult). Butterflies and moths live and breed in diverse habitats, including salt marshes, mangroves, sand dunes, lowland forest, wetlands, grasslands and mountain zones. Rock surfaces and bare ground are critical – they are home to the lichen eaten by the larvae, and offer adults places to bask in the sun.
Butterflies and moths abound in most habitats. The particular mix of species depends on the season, time of day, and other plants and animals at the site. Any given locality may have 400 to 750 species. Some fly at night and some fly during the day. Different species emerge as adults at different times of the year. The summer’s warmth brings out the highest numbers, although some moths are only on the wing in late autumn or early winter.
It is a myth that moths are solely nocturnal. Some fly at dusk, while others – particularly adult case moths of the Psychidae family – are active at dawn. Diurnal (day-flying) moths include those in the crambid, larentiine, glyphipterigid, elachistid and choreutid groups.
In New Zealand the richness of species increases from north to south, and is surprisingly high in the mountains of the South Island. This is the opposite to the normal pattern, where the number of species increases towards the equator and tropical regions. New Zealand’s distribution has been shaped by the country’s geological history. In the past 5 million years ice ages and mountain-building have created many open habitats, which are the most favourable environments for butterflies and moths.
Few species are widespread. Forested areas have a relatively uniform moth fauna. In farmland and suburban areas, native and introduced butterflies and moths live together.
Some native species such as the porina moth (genus Wiseana) have adapted so well to lawns and pasture that they have become pests. Long-established exotic arrivals such as several species of clothes moth destroy carpets, stored dry products and clothing. Introduced species continue to arrive, but few become significant pests.
Some recent arrivals have become agents of biological control, selectively attacking weeds such as broom, wild parsnip or hemlock. Some species have been deliberately released to control troublesome plants. The gorse seed-pod moth (Cydia succedana) has been successfully established on gorse.
Special light traps can be used to attract and sample nocturnal moths. Their attraction is in fact confusion, but the method is effective – more than 100 species can be recorded in a night. Open-country day-flying species can be sampled by netting and sweeping.
Insects that metamorphose (change form) such as beetles, wasps, butterflies and moths are the most rich in species. This is because they are able to synchronise their life cycles to the environment, including extreme conditions where animals that remain unchanged all year cannot survive.
The life cycle of insects in the order Lepidoptera is fairly uniform. Adults lay their eggs on plants or other surfaces. Larvae (caterpillars) hatch from the eggs, then grow and metamorphose from pupae into adults.
Caterpillar lifestyles are diverse and intriguing. Sometimes they feed in the open, but more often they stay hidden. Most eat the seeds, stems, galls, leaves, flowers or leaf litter of certain plants. Others consume detritus, wood, hair or wool, or are carnivorous and eat other live invertebrates. Some species hide in a larval case, while others make a covering of leaves held together by silk. Some larvae live in underground tunnels, and others bore into wood.
Māori know butterflies as pūrerehua. They commonly call their pupa tūngoungou (meaning ‘to nod’), describing the pupa’s abdomen as it bends back and forth. Pupae were sometimes part of a child’s game:
‘Children are asked by their grandparents to hold the pupa gently between the thumb and forefinger and ask it questions, such as, “Am I a good girl?” Then the pupa will wriggle its abdomen up (“Yes”) or down (“No”).’ 1
During this stage, the larva encases itself in a chrysalis or cocoon while its wings grow. It does not eat, and the period of metamorphosis may last a few days or several months. At the end of this time it emerges as an adult.
With few exceptions, adult butterflies and moths have short lives. One week is long-lived, and two weeks is the upper limit before they get worn out. Adults prolong life by sipping sugar from flowering plants – and unintentionally carry male pollen to the female parts of the flower, fertilising the plant. A minority of Lepidoptera species spend the winter in diapause – a type of hibernation. They can live as adults for up to five months.
Because their adult lives are short, they are focused on reproduction. Adults must quickly find a mate, and females must locate a place to lay their eggs.
Crowe, Andrew. Which New Zealand insect? Auckland: Penguin, 2002.
Dugdale, J. S. Hepialidae (insecta: Lepidoptera). Lincoln: Manaaki Whenua Press, 1994.
Dugdale, J. S. Lepidoptera: annotated catalogue, and keys to family-group taxa. Fauna of New Zealand 14. Wellington: Science Information Publishing Centre, DSIR, 1988.
Gibbs, George W. New Zealand butterflies: identification and natural history. Auckland: Collins, 1980.
Hudson, G. V. The butterflies and moths of New Zealand. Wellington: Ferguson & Osborn, 1928.
Patrick, Brian H., and J. S. Dugdale. Conservation status of the New Zealand Lepidoptera. Science for conservation 136. Wellington: Department of Conservation, 2000.