There are moments in life when your path pivots. A toe firmly plants into the sandy earth and your direction changes.

One of those moments happened to a small child named Barbara in the 1930s, in the West Australian Wheatbelt to the east of Perth.

In the uncleared bushland surrounding the homestead where she lived with her parents and brothers, six-year-old Barbara noticed the holes in the ground made by trapdoor spiders.

"They inhabited the bush land around the farmhouse and the sheds," Barbara York Main recalled in an interview with John Bannister of the University of Western Australia (UWA) historical society in 2012.

"I was interested in the small things — the insects were on a scale that I could relate to," she said.

Dr York Main's love of these small things and the bush would drive her to become one of the most extraordinary scientists in Australia.

She wrote *the* book on Australian spiders. An expert on trapdoors, she studied the world's oldest spider for decades. But more than that, she wrote about the environment so eloquently it brought tears to farmers' eyes.

Wodgil and Wheatbelt

"Out of the east it came; into the hot silent stillness of the night there came a cool rusting waver of air. At first soft, with a stirring and shaking of leaves, then with a roar and a rush, the wind came tumbling and rolling of the whole, wide, night-shrouded landscape. It rolled westward in gusts and rushes, finally to form a steady front of rushing air which at last swept strongly across the inland bushland, westward and south-westward across the indented edge of wilderness, across farmlands and broken, ragged stretches of timber and scrubby bush." Barbara York Main, Between Wodgil and Tor, 1967.

Dr York Main remained connected to the Wheatbelt and the wodgil — a type of dry scrubby bushland —throughout her life, according to West Australian literary historian Tony Hughes-d'Aeth.

"She understood the whole mythology of the Wheatbelt, and what it meant for those who committed their lives to the hardship of living there," Dr Hughes-d'Aeth wrote in his book 'Like Nothing on This Earth'.

"But she also understood, as few others could, just how special the natural world of the southwest was, and therefore the scale of the devastation that farming brought to these ancient ecosystems."

Both the wild, uncleared bush and the open fields were a part of Barbara's upbringing. ( ABC: Ann Jones )

He believes Dr York Main's detailed observation of Wheatbelt country, 'Between Wodjil and Tor', is a genuine classic of Australian nature writing.

"Barbara was a writer of rare power and beauty — one of the finest natural history writers that Australia has produced," Dr Hughes-d'Aeth said.

She wrote about and fought for the environment at a time when both the environment and women were given no fighting chance.

The lady of the spiders

Dr York Main was very clear about what she wanted to do when she arrived at UWA in 1947.

"I wanted to be a naturalist or a biologist in a formal educated sense and at the same time to be a natural history writer," she said in John Bannister's 2012 interview.

Scientists Barbara and Bert Main using a microscope in 1956 ( Supplied: Monica Main )

And she stood out according to Ernest Hodgkin, who supervised her honours project.

"The first I was aware of the lady [when I was] told that a student in the University Women's College kept spiders in her room, not the sort of activity generally associated with young ladies, even university students," Hodgkin wrote in the WA Museum Records and Supplements.

"Remember it was a time when the University Visitor, the Lieutenant Governor, in his annual speech to the graduation ceremony told women graduands they should stay at home to reproduce and care for their husbands and families," he wrote.

In 1956, Dr York Main, now married to fellow scientist and Albert (Bert) Russell Main and pregnant with their first child, became the first woman to graduate with a PhD in zoology from UWA.

Together the pair became a centre point for the study of zoology in Western Australia — a scene of young and energetic academics.

"One of the images of mum that I have is her looking down the microscope and then drawing a line drawing of the spider — an incredibly accurate drawing on graph paper", Monica Main, one of her daughters recalled.

Barbara Main's line drawings of different spider species. ( Supplied: Monica Main )

While her husband was eventually employed at UWA, and went go on to hold various important administrative roles in government, Dr York Main didn't receive a salary from the university.

"Women were not overly encouraged," she recalled, referring to Professor Harry Waring who was the head of the faculty at the time.

"He would encourage women to do a higher degree but... he didn't like employing women in the department as such, because he took the line that they were going to go and get married and then you'd have to get somebody else to fill that position," she said.

"He encouraged me in a sense to do research, but there was no possibility of me ever getting a formal position."

Scientists Barbara and Bert Main in 1955 ( Supplied: Monica Main )

Number 16

"Half obscured in the mat of litter beneath the jam trees and sheokes were the round, flat, litter doors of trapdoor spiders... "As passing insects disturbed the outer ends of the radial twigs the spiders rushed out, flipping back the light wafer doors, which then stood open, and ran out along the twigs or 'feeling lines' to catch the prey, turning about and returning quickly to the burrow. Barbara York Main, Between Wodgil and Tor, 1967.

Trapdoor spiders are known for not venturing far from home.

Young spiderlings emerge from their mother's burrow when they are around three months old to build their own home, just centimetres away.

The hole the spiders dig is perfectly sealed with a plug-like lid, which hinges on silk. And around the entrance an array of leaves radiates out — each one connected with a filament of silk.

Trapdoor spiders wait in their burrows for prey to come along and touch the leaves around the door, then they pounce. ( ABC: Ann Jones )

When the slightest movement taps any one of those leaves, the message is received by the spider in its burrow — like feeling the footsteps of someone coming towards you on a trampoline.

The first time Dr York Main flipped the lid and shone a torch into the burrow on the North Bungulla Nature Reserve it was 1975.

The trapdoor spider (Gaius villosus) she found — and named Number 16 — was one year old and yet to reproduce.

But, the spider had built herself her home, a place she would never leave until she died 43 years later.

Number 16 lived until she was 43 years old. ( AAP: Curtin University )

And for all but one year of that lifetime, Dr York Main visited the spider's burrow at least twice a year to check on its welfare and track what was happening to its environment.

Leanda Mason now looks after the longitudinal study that Barbara began in the 70s.

"Every year we would come back out here, we'd check on all the spiders and we'd both make a beeline to Number 16 to see if she was still alive," said Dr Mason of Curtin University.

Originally, Barbara had intended a study of 20 years, but Number 16 persisted, breeding every two years or so, becoming a great matriarch of a growing family of spiderlings.

"Barbara's eyes glowed fondly when she talked about her spiders to me, like she recalled an old friend rather than a specimen of study," Dr Mason said.

"It was obvious that the fuel that had sustained her over the decades was how deeply she cared."

Barbara York Main cared deeply for the spiders of Western Australia's wheatbelt. ( ABC: Ann Jones )

Mark Harvey from the terrestrial zoology department at the Western Australian Museum agreed.

"I felt her pain when she visited sites that once contained flourishing populations of her beloved trapdoor, that were now desolate and empty," Dr Harvey said.

"She would cast her arm across the hill recalling that in the 1950s there were dozens of burrows, but somehow the population had since been decimated.

"I never saw her more anguished when she returned to a site to find the spiders gone. It was a dagger to her."

The cycle of life

"The soil still shifted with the wind." Barbara York Main, Between Wodgil and Tor, 1967.

Eventually, Number 16 turned 40 and York Main hit her 80s, still visiting her spiders, still writing.

But, she began to show signs of Alzheimer's and slowly withdrew from her intellectual and field work before moving into a care home.

Dr Mason continues Barbara York Main's work with the spiders. ( ABC: Ann Jones )

In 2016, Dr Mason visited North Bungulla and made a beeline for the burrow of Number 16. Her huge perfect burrow was in disrepair. The lid of the trapdoor was pierced. The world's oldest spider had been killed by a wasp.

For the young scientist, the hardest bit was not necessarily the death of Number 16, it was that she had to tell Dr York Main that her grand old spider had gone.

Vale Barbara York Main

"The day after fire had run riot through the sandplain scrub, nothing moved in the devastated landscape. Nothing stood except the black, charred, leafless sticks of what had been trees." Barbara York Main, Between Wodgil and Tor, 1967.

The reserve at North Bungulla is quiet all day until the winds of the evening make the trees creak in the falling light. Last week, the winds brought news that Barbara York Main had died aged 90.

"Her immense publication record barely scratches the surface of what she learned about the Wheatbelt while she was alive," Dr Mason said.

"I could list the stats but I feel like it doesn't really encompass the fullness of her knowledge. There's so much she wanted to publish on and then she just didn't have time."

Dr Mason intends to continue the North Bungulla study.

Dr York Main's legacy lives on through more than 70 species and genera she described and the 22 species and three genera named after her.

Her children and grandchildren survive her — as do the spiderlings and grand-spiderlings of Number 16 in her beloved and threatened wodgil in the West Australian Wheatbelt.

Dr Barbara Anne York OAM: 1929 - 2019

Number 16: 1974-2018

Hear about Barbara York Main's extraordinary life on Off Track on Radio National at 1.00pm Sunday or tune into the podcast.