Paper wasps and daffs in May – can home gardeners help document climate change?

Friday, 3 June 2022

Tropical Fruit Growers chairman Hugh Rose says New Zealanders can grow all sorts of tropical fruit, especially popular bananas and heat-loving pineapples. (Video first published in December 2021.)

Jenny Nicholls is a Waiheke-based writer and columnist.

OPINION: An unruly star jasmine creeper sprawls over our deck, its tendrils curling through the floorboards and around the legs of our old outdoor table. Every now and then I hack it back, but it is greedy and Triffid-like.

In summer, though, it fills the house with scent, and tiny white blossoms wreath the old table like a botanic Milky Way. This made a perfect lazy centrepiece for our Christmas table, from the year it grew big enough, 2017, until 2019. For the last two years it has bloomed too early, and the flowers have gone by Christmas Day.

Although the world is getting warmer, it is hard for most of us to point to anything tangible, unless we are glacier guides or have family in India. There are things which might mean something or nothing – a whiff of an early wisteria bloom, a bathwater-warm sea in March, sunburn on my neck in May, the whine of mosquitoes in June.

Chris Mclean in her kitchen garden in north Taranaki. She is standing under a tamarillo tree with vegetables just picked from the garden. Thousands of white fly feasted on her raspberries and tamarillo this summer.

New Zealand researchers are doing their best to monitor the effect of climate change on native flora and fauna. But there are other observers too, who have been running their own backyard experiments for years, although few of them might put it that way.

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More delights from the north Taranaki coastal garden Chris Mclean has tended for the past 44 years.

As Zach St. George wrote in The New York Times, “Gardening is fundamentally a local endeavour, an experiment in fitting plants to a specific soil and climate.”

Home gardeners nurse their private domains through pests, harvests, plagues, downpours and droughts. Some have tilled the same land for decades of triumph and disaster known mostly only to themselves.

Until recently, long-term records of climate change were kept by accident, in mariners’ logs, old diaries and harvest ledgers. I can’t help thinking that if someone combed through Instagram posts of ‘’weird’’ bugs, blossoming cherry trees and giant carrots, a map of shifting barriers of plant and insect might be charted, a slowly accumulating library of change.

Not being much of a gardener myself, I asked around, gathering impressions from the best I could find.

Chris Mclean has tended the same patch of north Taranaki coast for 44 years, growing a cornucopia of fruit, herbs and vegetables.

Her garden endured a long, hot summer this year, and white butterflies fluttered over it for much longer than usual. Thousands of white fly, she tells me, feasted on her raspberries and tamarillo. The invaders might explain a bumper crop of birds, which chowed down on plums, apples, pears and persimmon.

Chris Mclean’s garden contains sculpture by her husband, John.

Since Psyllid appeared three years ago, she says, growing potatoes from early summer is impossible.

Last year, her apple trees flowered out of season. And paper wasps arrived four to five years ago – Chris thinks they are Asian paper wasps, which reached Aotearoa in the 1970s. By 1995 they were a common sight during summer in the upper North Island.

Understanding how invasive species like European or Asian paper wasps spread is a challenge best left to entomologists, although it is worth keeping our eyes peeled. Milder winters, especially in the South Island, are helping the European paper wasp (which probably reached Aotearoa some time in 2011).

Dr Mike Dickison, who lives in Hokitika, says monarch butterflies are disappearing from their favoured spots – and paper wasps eat monarch caterpillars. European paper wasps have reached Dunedin, but not the West Coast yet, he says, as far as he knows. “I’m starting a community monitoring programme in summer.”

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I wondered if climate change might have helped paper wasps reach Chris’s garden in Taranaki, so I asked Victoria uni wasp expert Dr Phil Lester.

“Climate change will have a variety of effects on insects such as wasps – including the common or German wasps,” he tells me. Wasps do well in dry and drought conditions.

“The warm conditions we experienced in the autumn with a lack of frosts means that wasp colonies don’t die off. They may survive to a second year when they become ‘monster’ or really large wasp colonies. Because the effects of climate change are different for different regions, effects on populations will be different in different areas.

‘’In areas that become subject to more extreme wet weather events, we are likely to see fewer wasps. But for those areas subject to nice warm, dry wasp-growing conditions …” (I take the professor’s ellipsis to mean ‘‘insert Jaws soundtrack here’’.)

“The Australian paper wasp has a more limited distribution in the north – it is likely to be able to come to many areas of lower latitudes. The European paper wasp has only recently arrived in New Zealand, and we think is still spreading. I’m guessing it will very much enjoy the Hawke’s Bay, for example, when it eventually arrives there. And it will.”

Gardening writer Gareth Winter, who lives in Masterton, doesn’t like to jump to conclusions. “With diseases (like Daylily rust or Myrtle rust) it is hard to know whether they are spreading south [due to warmer temperatures] or if they are just new to the country.”

But he points out that many commercial berry growers have left Wairarapa, as the winter is no longer chilly enough there for a reliable crop.

“Some flowering bulbs are certainly flowering earlier in the spring,” he tells me. “My Snake’s Head Iris flowers about three weeks earlier than it did in the past.” He has also noticed the arrival of the Harlequin ladybird and paper wasps.

I have started to ‘bookmark’ tweets like this one, from nature writer Alison Ballance; she posted photographs of daffodils, kōwhai and kākābeak, the images of a stereotypical New Zealand spring. The post is dated May 31.

“So tomorrow is the first official day of winter in NZ. In Ōtautahi/Christchurch the flowers say ‘’yeah nah’’.

Jenny Nicholls at jnichollsnerdnation@gmail.com would love to hear from anyone who has seen paper wasps where they don’t belong, or strange samples of early flowering!