What do kiwi, tuatara and many butterflies have in common in New Zealand? They are all native animals that the average person rarely sees in the wild.
If you ask most people about butterflies, they can only name the monarch (a self-introduced species) and the white butterfly (an introduced species), but 17 species of butterfly live and breed in New Zealand.
Our butterflies are highly endemic – the majority of them are found nowhere else in the world. Why is this? A few of our native butterflies, like red and yellow admirals and the common copper or blue, are found throughout the country. However, they tend not to be garden butterflies, so you may need to leave the city to see them. Some of our other natives are so hard to find that experts aren’t even sure about the food plants their larvae eat or how long they take to go from egg to adult.
Why don’t we see native butterflies? There are several reasons. Some are due to the nature of the butterflies themselves and others are a result of human impact.
Inaccessible or disappearing habitat
Many of our native butterflies, like the tussocks and ringlets, live in alpine habitats so they are more likely to be seen by trampers than backyard gardeners. Their flight periods are strongly seasonal – perhaps only 3–4 weeks at a particular place. Alpine butterflies are active on sunny days and less so when the weather is cloudy or windy, making them more difficult to spot.
Native butterflies are also victims of habitat loss. People may grow milkweed plants in their gardens to feed the monarch caterpillars, but are not so keen to plant a patch of stinging nettles to attract admiral butterflies. Most of our natives rely upon larval food plants in forest margins and tussock lands. Introduced grasses for intensive agricultural production, grazed alpine land and tidy lawns don’t make good butterfly habitats.
Garden butterflies like the monarch and white tend to fly at human eye level so they are easy to spot. Forest ringlets are high-level tree top fliers. Females move to the forest floor to lay eggs but quickly fly to the canopy if disturbed. Blues and coppers fly close to the ground so they are easily overlooked.
Nature of Science
Funding influences the direction of scientific research. To fill knowledge gaps about native butterflies, funding agencies must be convinced of butterflies’ importance in our ecosystem. As our butterflies are less visible than tuatara or kiwi, they gain less attention and less funding. There is a fear that, because we know so little about some butterfly species, we won’t know what we’ve lost when they are gone.
Camouflaged hind wings
Native butterflies are cleverly camouflaged to fit in with their surroundings. Although the upper sides of their wings are colourful, the hind wings (underside of the wing) are dull and patterned so the butterflies blend in when their wings are closed. Big, bold butterflies like the monarch are easy to spot. If you want to see some of our natives, careful observation is the key.
Small wing size
Our more common garden butterflies have large wingspans. Monarchs can have a wingspan of up to 110mm. Compare this to a southern blue whose wingspan ranges from a tiny 17–21mm. Tussock butterflies average 30–40mm wingspans. The coppers’ wingspans range from 17–32 mm. The combination of small wingspan and camouflaged hind wings makes these natives difficult to spot.
Sluggish life cycles
The non-native white butterfly is capable of producing 5 generations in a favourable year. Our natives are slower to reproduce. Many of the tussocks and ringlets have a 1–2 year life cycle. Black mountain ringlet larvae may take 2–3 summers to grow to their full size.
Predation by wasps
The admirals and forest ringlet butterflies have been hit particularly hard by the introduction of wasps. Pteromalus puparum and Ichneumon wasps were introduced as biological control of the white butterfly. The Australian wasp (Echthromorphia intricatoria) found its own way to New Zealand. These parasitic wasps lay their eggs in butterfly pupae, and the newly hatched wasps use the pupae as a food source. Wasps have an altitudinal limit of 600m so most of our alpine butterflies avoid this risk.
Visit nzButterfly.info to learn more about native butterfly habitats and life cycle information.