A century ago, Wellington naturalist George Vernon Hudson collected thousands of moths in the bush next to his home, in what is now Zealandia sanctuary.
Now a group of citizen scientists are following in his footsteps, collecting moths to see how the numbers and species of moths have changed over time as the local vegetation has changed.
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Macro moths collected in late summer at Zealandia sanctuary as part of the 100 Year Moth project. Clockwise from top left: Proteuxoa sanguinipuncta, Pseudocoremia sp. (centre), Declana floccosa, Bityla defigurata & Ichneutica plena. Photo: Andrew Simpson
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For nearly six decades, in the late 1800s and early 1900s, Wellington naturalist George Vernon Hudson walked in the bush next to his Karori home two to three nights a week, collecting moths.
He was a keen observer, finding well-camouflaged moths as they sheltered on tree trunks or on leaves.
He beat bushes with a large stick, using a large upside-down white umbrella to catch moths as they tumbled out.
Back home, he painstakingly prepared the specimens, writing tiny identifying labels that he hid under each moth when he pinned it into a specimen box with its wings carefully arranged.
The details of each specimen were entered into a large ledger, carefully coding what it was, and when and where he’d collected it.
Hudson prepared detailed illustrations of many species, which were as artistically beautiful as they were scientifically accurate.
On his death, the insect collection, illustrations and diaries were gifted to New Zealand’s National Museum, now Te Papa Tongarewa.
George Vernon Hudson’s life work spans 1881-1946 and is the single largest insect collection in New Zealand.
A group of keen citizen scientists at a monthly moth-catching session in Zealandia sanctuary. Moths are attracted to the bright light and are easy to see against the white sheet. Photo: RNZ / Alison Ballance
A century later
A hundred years later, George Vernon Hudson’s grandson, entomologist George Gibbs, is one of a group of keen citizen scientists following in the moth collector’s footsteps.
The 100 Year Moth Project is an Entomological Society project in association with Zealandia sanctuary, which is a short stone’s throw from Hudson’s moth haunts.
The team assemble in Zealandia once a month at twilight to set up the light trap, which consists of a bright ultraviolet light, powered by a generator and positioned on a white sheet on the ground.
Moths are attracted to the light and settle around it on the sheet. Half a dozen keen spotters identify different species of moths and collect a few examples of each kind, with most moths being left alone.
This looper moth is a species of Xyridacma, which is a kind of Geometrid moth. Photo: Andrew Simpson
Crowd sourcing moth identification
William Brockelsby is the organiser of the 100 Year Moth Project, and he says they collect between 20-50 species in a night. The exact species vary from month to month.
“In seven months we’ve barely scratched the surface in terms of what we know should be around here,” says William.
Entomologist Eric Edwards, from the Department of Conservation, says a few of the larger species can be identified straight away, but others – especially tiny micromoths – need to be identified by experts.
The project is using the iNaturalist app to crowd source identification. It is an easy matter to post a phot of a moth, allowing experts anywhere in the world to offer suggestions as to what it is.
The specimens collected by the project will be added to the insect collection at Te Papa.
A moth trap involves a white sheet and a bright ultraviolet light to attract moths. Photo: RNZ / Alison Ballance
Moths are good botanists
Mahoe stripper (Feredayia graminosa) is a regular visitor at the light trap at Zealandia sanctuary. Its caterpillars feed on mahoe leaves. Photo: Andrew Simpson
Eric says the project is an opportunity to revisit history and discover what has changed in a hundred years. Hudson’s original collection provides the baseline against which the new collection will be compared.
There are many questions: what species are the same, what has changed and what has been lost?
The changes in the moth population will directly reflect changes in the vegetation.
“Moths tell a powerful story,” says Eric. “because moths are good botanists.”
“A female will only lay eggs on the plant that suits her caterpillars to grow on. So when you see the moths you’re actually seeing the flora.”
The original plan was to sample moths in the sanctuary’s forests once a month for a year. While the COVID-19 pandemic has interrupted this schedule, the group had seven collecting sessions already under their belt before the lock-down prevented the regular get-together and collecting will resume as lock-down eases.
Listen to the full story to hear George Gibbs talk about his grandfather’s pioneering insect collecting, and to hear about some of the moths that the team collected in late summer.
Moths at home
If you would like to identify common moths that you might see where you live, then check out the Te Ahi Pepe / Mothnet moth ID guides, which are freely downloadable from Manaaki Whenua Landcare Research. You’ll find other free moth guides there as well.
Listen to the Our Changing World interview ‘Shedding light on the world of moths’ to find out more about Te Ahi Pepe / Mothnet citizen science and school projects.