One crisp spring evening, just on dark, an older man and a middle-aged woman met on a lonely bush track to inspect a patch of scrub by torchlight. They progressed purposefully, quietly and mostly on their knees. Their interest was restricted to a sparse area measuring about half a house block. Rarely did the torch beams stray to the unimpressive eucalypts, which were grey box.
The air was still; not a single vehicle passed in the hour they peered and prodded. Until recently, when car access was thwarted by three large boulders, this spot - a revegetated goldfield on the outskirts of Castlemaine, in central Victoria - was a Friday-night haunt of parking teenagers. From time to time one of the torches would light upon an empty pre-mixed-drink bottle, a sun-bleached chip packet, bits of glass.
The Friends of Kalimna Park were searching for larvae of the exceedingly rare Eltham Copper Butterfly. Paralucia pyrodiscus lucida, which was discovered in the Castlemaine Botanical Gardens in 1897, was presumed extinct until its rediscovery, 22 years ago, in Eltham, part of Melbourne's northern sprawl. Small colonies have been found near Horsham and Bendigo, but Kalimna Park, where Paralucia was found in 2002, is regarded as giving the species its best chance of long-term survival.
Every October for the past five years, the Friends have volunteered four successive Monday nights to count Paralucia caterpillars, which are small, pale green and nocturnal, as part of a La Trobe University survey. This was the second night of counting for 2008. I'd told Geoff, the Friends' secretary, that I'd be there at a quarter past eight. I figured the group was a social thing, like a book club, only with species instead of books. Maybe there'd be wine afterwards.
"I'll probably be out on my own," Geoff had said. "One or two have said they'll come, but I'm tired of chasing people up." He did sound tired. "If you're there, you're there," he said. "I'll be there."
At five to eight I rang Geoff to say I couldn't find my torch. (Four Corners beckoned, too.) But I only got his message bank, so I had to show up. Also at the appointed spot was Robyn, a retired teacher. Geoff looked as he'd sounded: a little dour, a little sad, with a short grey beard and a kindly face. We made minimal small talk. The air was nippy; Geoff and Robyn were keen to get the job done and go home. I was given a torch and a brief spiel.
In this patch of bush, I was told, lives a plant called Bursaria spinosa, or sweet bursaria. Robyn showed me a specimen: it looked pathetic, even objectionable - you wouldn't venture to call it a shrub. It was a few spindly stems averaging about half a metre in height. Tough, tiny leaves sprouted from the stem in ruffs, interspersed with sharp prickles.
In summer, Paralucia feed on the nectar of the bursaria's white flowers. They lay their eggs near the base of the plant, in the leaf litter, where an ant of the genus Notoncus nests. From the moment an egg hatches into a caterpillar, the ants look after it. They take it into their nesting chambers by day, escort it up the stems at dusk and shepherd it all night as it munches leaflets. It's believed that in exchange for protection from bugs and predators, the caterpillar provides the ants with vital secretions.
Our task was to locate caterpillars as they inched up the stems. We'd identify Bursaria spinosa - there are plenty of scraggly pretenders - then examine each stem from top to bottom for a bristling node of the black and beady ants, because four or five tended to accompany each stem-coloured caterpillar.
I'd hardly started when Geoff pointed out a puny bursaria stalk that had been broken off, possibly by me. "That's unfortunate," he said. It was going to be a long hour. To make it pass, I tried chatting. Geoff mentioned the likelihood of a housing development below the ridge, in a paddock called Happy Valley. I wondered what harm houses and people down there could do. "More dogs," he said. "More kids building cubbyhouses. It all adds up."
We worked quietly for a time. It seemed wrong to speak across the stunted shrubbery in the still night air. By the time I spotted my first caterpillar Geoff and Robyn had found 14, but it still seemed significant. I peered at it so long that it wriggled around to nudge back down the stalk. Evidently it didn't like torchlight, or maybe it figured it was day. The caterpillar's four guardian ants descended with it.
Further up the stalk there was another caterpillar, and another. Geoff came over with his clipboard to note the size and number of the grubs, and the height and ID number of the plant. Some plants bore small metal tags. Those that didn't got a new one.
We chatted during these administrative moments. Geoff, a retired public servant and occasional violinmaker, didn't consider himself to be Kalimna Park's best Friend. That was his partner, Anne. She loved the park, its birds and animals, its fragile orchids, the chocolate lilies, the little orange butterflies - and, being a district nurse, she knew need when she saw it. She tackled the Enemies of Kalimna Park - invasive, bursaria-obliterating weeds such as blackberries, gorse and broom - and revegetated at every opportunity. She even planted bursaria in her garden, and had discovered a second Paralucia colony on the edge of Castlemaine, just a few minutes' walk from my front gate. No one was more dedicated to the park's health than Anne, Geoff said softly.
He moved back to his section. It took me 15 minutes to find another caterpillar, and to find out what happened to Anne. She was run over by a car. "It has been a tough year," Geoff said, peering at leaflets rendered colourless in the glare of his torch. "Still is."
I began looking harder for caterpillars. I started to see a design behind the deceptively casual way the ants crawled all over and around the larva. Under time-lapse photography, I felt sure, the caterpillar would show up as possessing a black outer shield. I liked the way it didn't flinch, the intimacy of it all. The ant would struggle without the caterpillar. The butterfly would vanish without the ant. Both would be lost without sweet bursaria. And their patch of habitat measured just 20 by 20 metres, if that.
I also found myself wanting to find caterpillars so that Geoff would come over and talk. His voice seemed to melt into the scrub, natural as the dry crackle of leaves under our knees. He took care not to part the bursaria stalks as he shone his torch over them, in case the vibrations disturbed a caterpillar and sent it squiggling back down the stalk on an empty stomach.
One day soon the caterpillars would spin themselves into pupae, then wrest themselves free as butterflies. What would the ants do then? Geoff didn't know. He wasn't much into musing. "I'm really carrying this on to honour Anne," he said, without looking up, as he jotted down another caterpillar's particulars. "We did it together, but she was the conservationist, the one who loved nature so much that I couldn't help but be taken along. This was always her thing."
Too soon, the white light of Robyn's rechargeable torch, then mine, began to wane to yellow. The hour had stretched to 70 minutes and 24 caterpillars. We arranged to meet - same time, different colony - the following week, by a bench I knew well. I asked Geoff if he would be coming back here in a few months, to observe the bursts of Paralucia blinking orange in the summer sun. "Of course," he said. "I'll be here quite a bit."
