Moths, along with butterflies, are part of the order Lepidoptera (from the Greek for scaled wings). Over 90% of New Zealand’s Lepidoptera species are endemic, found nowhere else in the world. From these 2,000+ species, only 17 are butterflies – the other 98% are moths! Many of the moth and butterfly species are found in rural, forested or alpine regions, so they are not commonly encountered by people.
Moths and butterflies
Moths and butterflies look similar, but can be quite different. In general, moths tend to be drab in colour, fold their wings down flat when resting and are usually nocturnal. On the other hand, butterflies are often brightly coloured, hold their wings together and upright when resting and are usually diurnal. However, these features can vary between species so are not guaranteed ways of identifying between moths and butterflies.
The best way to tell moths from butterflies is to look at their antennae. Moth antennae taper to a point and are either feathery or thread-like. Butterfly antennae are never feathery and end with expanded knobs. This is the case for all butterflies found in New Zealand, so it is an excellent way to distinguish between them based on appearance.
Moth life cycle
The life cycle of moths follows a general pattern. Eggs are laid on the surfaces of plants and later hatch into caterpillars (larvae). These larvae consume food around them, often plant matter and detritus, but sometimes other invertebrates (in the case of carnivorous species). All this eating gives the caterpillars energy to grow. Eventually, they will encase themselves in a cocoon for protection, and while inside, they begin to metamorphose into adults. The pupae are unable to eat and must survive this period using the energy from when they were caterpillars.
When they finally hatch out, they are fully grown adults. Now the moths race to find a suitable mate and reproduce. They don’t have long, because the lifespan of adult moths is short – usually only a week or two! Once they lay their eggs, the adults die, and the cycle begins again.
Quirky moth characteristics
Many of New Zealand’s moths display a particularly unusual characteristic: flightlessness. In most of these species (such as Gadira petraula, found in the South Island near Banks Peninsula), it is only the adult females that are flightless. Another example of a flightless moth is the diurnal Orocrambus fugitivellus. Again, it is only the female who is flightless.
One genus of New Zealand moth, Metacrias, is even weirder. After laying her eggs, the female remains in the cocoon until they hatch. The tiny caterpillars then proceed to eat her, recycling her energy and giving them a head start in life. This is the only time they are carnivorous – from then on, they only eat plant matter!
Why moths are important
Adult moths provide both food sources for native bird species and act as important pollinators for plants. Due to short lifespans and good mobility, moths are excellent indicators of environmental change. By further understanding the relationship between New Zealand’s moth species and their environments, we can begin to predict how they will be affected by climate change. By extension, we can judge the health of the environment and other native species. This is very important!
However, to properly understand how moths interact with the native ecosystems, more study is needed. Moths generally go unnoticed, and there isn’t much public interest in them. There is also a lack of understanding of the effects of introduced species and competitors, for similar reasons. We need to start recognising the importance of these little insects and their vital role in the ecosystem. The Ahi Pepe MothNet project is working to raise the profile of moths with the public. Ahi Pepe MothNet partners are enthusing schools about moths and the value they have within an ecosystem.
Visit the Ahi Pepe MothNet project website for resources and more, including free, downloadable regional guides, in both te reo Māori and English. Watch the video Moth Net: Shedding Light on the Night for an overview of the project.
New Zealand’s Biological Challenge – one of the National Science Challenges – helped to fund the national Ahi Pepe MothNet project. Find out what they are doing to enhance and restore New Zealand’s ecosystems.
Angus Gaffney produced this article while completing a third-year Otago University internship paper with the Hub.