Robert Hoare

Moths and the night

Spring is here, and the moths are emerging. Overwintering as a pupa, they emerge when the temperatures rise, to mate and lay eggs so their caterpillars can spend summer and autumn feeding and growing. A month ago, a light trap at Gordon Park would attract just one or two moths, but now, after an hour, the white sheet is covered with moths large and small, wasps that parasitise moths, flies, beetles and other nocturnal life. New Zealand has over 1,700 species of native moths, many barely known or still undescribed, and Robert Hoare at Landcare Research is the only full-time researcher working on them – his plate is pretty full.

2. light trap

Light Trap: Using LEDs in the blue and ultraviolet parts of the spectrum shining on a white sheet attracts nocturnal insects, which confuse it with the moon—the only bright light they’ve evolved to deal with. Photo: WRM.

While waiting at a light trap, being savaged by mosquitoes, you’ll occasionally hear a loud rustling and flapping as a huge pūriri moth (Aenetus virescens) or pepetuna, blunders into the sheet. Adult pūriri moths have beautiful mottled green wings, but they have no mouthparts and don’t feed, living on stored fat for the few days it takes them to find a mate and reproduce. In contrast to their brief adulthood their caterpillars, called mokoroa, live for years in holes bored into tree trunks; wētā will often move into the vacated tunnels. Once very common in North Island, pūriri moths are now only seen around native bush. In times past, swarms would emerge and fly into houses, extinguishing lamps and candles.

1. puriri

Pūriri moths emerge on damp nights in September and October to mate, lay thousands of eggs and die. Photo: WRM.

The decline in moth numbers is something that’s been noticeable, even in my lifetime. When I was a child, long drives at night left the windshield plastered with insects, but hardly ever so today. True, cars are more aerodynamic now, but the decline is certainly real, at least in Europe where it’s been carefully measured. Scientists, managing annual light trapping in Germany since 1989, have measured real declines in the numbers of nocturnal insects, down on an average of 45%, or 80% in some areas. There’s been no funding for this sort of long-term monitoring in New Zealand, so we have to rely on anecdotes about windscreens.

3. forest looper

Also known as the conifer flash (Pseudocoremia leucelaea), this moth is common in native bush in spring. Its caterpillars feed on tōtara and miro leaves.  Photo: WRM.

This insect decline has multiple causes: deforestation of course, the switch to intensive agriculture reducing the diversity of habitats in our farmland and the widespread use of pesticides. Systemic pesticides like neonicotinoids are restricted in Europe but widely used in New Zealand, and most discussion of their impact is around their effects on honeybees, not our thousands of native species.

4. cranefly

There are over 600 species of craneflies in New Zealand. Sometimes mistaken for a gigantic mosquito, they are harmless.  Photo: WRM.

Even artificial lighting might be a problem. Everywhere, including Whanganui, old high-pressure sodium street lighting is being replaced with modern LEDs, which are brighter and far more energy efficient, saving councils millions of dollars annually in electricity costs. The problem is that sodium lights were orange, whereas LEDs shine in the blue end of the spectrum, like those in my fancy new German light trap. Blue lights are far more visible and confusing to insects. In the name of energy efficiency, we’re busily lining our streets with thousands of high-powered insect traps, without much thought about the effects on nocturnal pollinators like moths.

Human beings have transformed the night, replacing the moon and stars with so much artificial light that we’ve forgotten what darkness is. When I lead night walks at Bushy Park we stop and do a simple exercise of turning off all our torches. Some of the children in the group are then in complete darkness for the first time in their lives. For many of the creatures of the bush, the night is their habitat, the place they can’t be seen by predators. They evolved in a world that had darkness, and in just a few hundred years we’ve driven that away.

 

Dr Mike Dickison is Curator of Natural History at the Whanganui Regional Museum.

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Discovering new species

When a new species of plant or animal is discovered it’s a big news story, but the secret amongst biologists is that it’s actually easy to find a new species. It’s hard to convey to people just how many species remain to be discovered, and how few people there are left looking for them.

Undiscovered jumpers: There are over 50 species of cave wētā, or tokoriro, in New Zealand, which, despite their name, live mostly in the forest. So many new species are being discovered that there is a backlog waiting for the few entomologists who study wētā to find the time to describe and name them. Creative Commons BY-NC, Jon Sullivan / Flickr

Undiscovered jumpers: There are over 50 species of cave wētā, or tokoriro, in New Zealand, which, despite their name, live mostly in the forest. So many new species are being discovered that there is a backlog waiting for the few entomologists who study wētā to find the time to describe and name them.
Creative Commons BY-NC, Jon Sullivan / Flickr

There are probably undescribed species living in your backyard. Entomologist Willy Kuschel spent 15 years collecting beetles in the Auckland suburb of Lynfield. He found 982 species of beetle, far more than anyone would have suspected could be living 10 kilometres from the central city. Amazingly, 150 of those beetles were new to science. Nobody had noticed them because nobody had looked.

There are probably species to be discovered in Springvale and Aramoho, but if I wanted to find one I’d start at Bushy Park, one of the last remnants of lowland forest in this part of the country. Bushy Park has never had biologists do a comprehensive survey of its insects, snails, and spiders, so we have no idea what’s there. Collecting a scoop of leaf litter from the forest floor and picking through it might well reveal species surviving there and nowhere else.

The stick that moves: A new species of stick insect found only on the Poor Knights Islands was recently named Clitarchus rakauwhakanekeneke, in conjunction with local iwi Ngāti Kuri. Its Māori name means “the stick that moves”. Thomas Buckley / Landcare Research

The stick that moves: A new species of stick insect found only on the Poor Knights Islands was recently named Clitarchus rakauwhakanekeneke, in conjunction with local iwi Ngāti Kuri. Its Māori name means “the stick that moves”.
Thomas Buckley / Landcare Research

The scientists who do this sort of survey and name new species are called taxonomists and their work is the foundation of all conservation policy and ecological research; you have to be able to list and name the living things in an area before you can measure how they’re doing or develop a management plan. Taxonomic research has always been the mainstay of museums, which have large comparative collections. But museums all over the world have been cutting back, and New Zealand is no exception.

 

When I was a lad I was mad keen on lizards, and conventional wisdom was that we had a dozen or so species in New Zealand. Since we started looking closely at lizards and their DNA, it turns out there are actually about 100 species, but there are only a handful of scientists able to formally describe them and give them names. The most recent field guide to native lizards has to refer to fairly-widespread species with labels like “Genus B species 1”, because we don’t have enough taxonomists.

Thambotricha vates, a Latin name that translates as “wonder-haired prophet”, has been found by entomologists for the first time since 1996. This elusive moth has only been seen 15 times since it was described and named in 1922. Creative Commons BY-NC, XXXXXXXXXXX / Flickr

Thambotricha vates, a Latin name that translates as “wonder-haired prophet”, has been found by entomologists for the first time since 1996. This elusive moth has only been seen 15 times since it was described and named in 1922.
Creative Commons BY-NC, XXXXXXXXXXX / Flickr

Even after a species is described, we don’t know necessarily know anything about it. Recently a small moth, Thambotricha vates, was caught by Landcare entomologist Robert Hoare. It had last been seen in 1996 and only 15 specimens had been collected by scientists since it was first described in 1922. Because it’s found from Nelson to Katikati, it probably isn’t rare; we just don’t know its habitat. Although the media treated this rediscovery as a big story, it isn’t all that exceptional. There are over 1,700 species of moths in New Zealand, and some of our 10,000 insect species have almost certainly been seen just once, by the entomologist who described them.

 

In NZ there are many species of native earthworms, some of them gigantic. In all the gardens, parks, and farmland of NZ the earthworms are just a few introduced European species. Unfortunately we know very little about native earthworms; many have been found from deep in the subsoil, living in a single patch of native bush. Thirty species occur only on a single small island each, but 102 species are listed as “data deficient”. They could be widespread, or on the verge of extinction – we don’t know. And there are surely native earthworms still unknown to scientists, which might go extinct before they’ve even discovered.

A new species washed up on the beach: George Shepherd, Curator at the Whanganui Regional Museum in 1933, measuring the skull of the beaked whale that was eventually named Tasmacetus shepherdi in his honour. Whanganui Regional Museum Collection 1805.296.2

A new species washed up on the beach: George Shepherd, Curator at the Whanganui Regional Museum in 1933, measuring the skull of the beaked whale that was eventually named Tasmacetus shepherdi in his honour.
Whanganui Regional Museum Collection 1805.296.2

Not all new species are moths and worms. There are still discoveries to be made in the deep sea, even of large marine mammals. The Whanganui Regional Museum still has the skeleton of a beaked whale that washed up on the beach near Hāwera in 1933, and was collected by George Shepherd, the Curator at the time. He recognised it was unusual, and sure enough it turned out to be a new species. Shepherd’s beaked whale (Tasmacetus shepherdi) lives in deep water far from shore, in cold southern seas, so live animals have been seen only a handful of times. Most of what we know about them comes from stranded specimens.

 

New techniques can also help discover species that were hiding in plain sight. When the DNA of kiwi populations all over New Zealand was compared, the birds around Ōkarito on the West Coast turned out to be very different from other brown kiwi. Collectors in the 19th century had noticed this, and used the name rowi to distinguish them from other kiwi. The DNA evidence was enough to establish them as a new species, Apteryx rowi, numbering just a few hundred birds in one patch of forest. They now have their own captive breeding program.

Saving a subspecies: The Hector’s dolphin (Cephalorhynchus hectori) has North Island and South Island subspecies that can interbreed. The North Island form, or Maui dolphin, is in danger of extinction, but saving it shouldn’t be as high a priority as all the other actual endangered species in New Zealand. Creative Commons BY-NC, Earthrace Conservation / Flickr

Saving a subspecies: The Hector’s dolphin (Cephalorhynchus hectori) has North Island and South Island subspecies that can interbreed. The North Island form, or Maui dolphin, is in danger of extinction, but saving it shouldn’t be as high a priority as all the other actual endangered species in New Zealand.
Creative Commons BY-NC, Earthrace Conservation / Flickr

Without the attention of taxonomists the rowi might have quietly gone extinct while we were distracted by showier things like Maui dolphins (which are not actually a distinct species, just the Hector’s dolphins that happen to live in the North Island). The worst scenario is discovering much later, from museum specimens, that something collected a century ago is both a distinct species and no longer to be found in the wild. How many species have we already lost, species that we’ll never know about, because we didn’t notice them in time?

 

Dr Mike Dickison is Curator of Natural History at the Whanganui Regional Museum.