FAIRIES OF THE NIGHT
Glow worms in the Blue Mountains
STUMBLING IN THE DARK, I follow the leak of light from the headlamps of those ahead, creeping through a rugged gorge bordering Wollemi National Park (in Berambing, 10 minutes from Bilpin, New South Wales) searching for glow worms. It’s an exhilarating experience.
Jochen Spencer, founder of the Blue Mountains Glow Worm Tour, reveals the rarity of simply walking about in the bush at night is a highlight for many on his tours. In fact, the glow worms we’re about to see were discovered by a tourist on a drunken nighttime ramble.
The air, as we descend into the ancient canyon, is iron cold and stinks of rotting vegetation. A stream rattles in the dark and a haze of moonshine watches beyond the gloom of trees. While I’m negotiating a slippery rock, trying not to think about snakes, the headlights of the tour group (restricted to an intimate troop of eight) float into the distance, and I’m swallowed in a heart-pounding darkness.
Another twist and turn down the dark, wet, stony descent, and I’m standing in a natural sandstone amphitheatre staring at a sea of sparkling blue-green lights. It’s like walking into an enchanted forest.
According to David Merritt, associate professor at the School of Biological Sciences, University of Queensland, the glow worm isn’t technically a worm, but the bioluminescent larvae of a type of fungus gnat of the genus Arachnocampa (spider-worm). Cultural misunderstanding has led to Arachnocampa being confused with fireflies. (The latter, a type of beetle, is also called glow worm in Britain, Europe and the United States, says Merritt.) Special cells in the posterior of the insect’s gut produce light emitted through transparent skin. Reflector cells, in their respiration tubes, enhance the display; they’re the only insects known to produce bioluminescence in this way.
The genus is unique to Australia and New Zealand, in that eight of the nine known species of Arachnocampa are found only in Australia; one in New Zealand, he says.
Merritt, who has been studying glow worms for more than 18 years, explains that their tiny size (about a centimetre), hidden habitats, and the fact forest glow worms ‘switch off ’ in daylight, is why few of us have ever seen them.
Within Australia, glow worms live in dense rainforest patches and dark caves in Queensland as far as the Wet Tropics, and down to New South Wales, Victoria and Tasmania. “If you just plonked
yourself in the middle of a rainforest, you wouldn’t see any,” says Merritt. “But if you walked till you found a stream, one that’s got steep banks with tree ferns and that sort of thing, wander down there and get totally wet, you’ll probably see glow worms.” They thrive in cold, dark, wet, sheltered environments with persistent humidity, he says. “You often see them concentrated around waterfalls and in caves with a stream.”
It’s unknown how many glow worms exist in Australia. “Who goes blundering through the rainforest in the night?” Merritt says. “Even park rangers don’t know they’ve got glow worms.” He estimates there are probably thousands of colonies. “People who do canyoning see them all the time. They’re probably more widespread than we know.”
According to Spencer, the Berambing glow worm colony hosts about 10,000 individuals and extends all the way into the canyon. Climbing up on the viewing platform, we’re able to get close enough to view the vertical string-like fishing webs they cast to snare prey such as mosquitoes and midges, lured to their fatal light. “No other tour in Australia lets you get so close to glow worms,” Spencer says.
We’re told to switch off our torches, camera flashes and phones, and whisper – the highly sensitive glow worms extinguish their lights in response to sound and light. This affects their ability to catch prey, and such tourist impacts have reduced some glow worm colonies.
While glow worms peak over the summer period, they can be seen all-year round, he says. “They spend about one year in the larval stage and only live about four days as an adult to reproduce.” The less alluring adult gnat looks like a mosquito.
The glow worms aren’t the only thing lighting up the night in the canyon. In December, visitors are likely to be rewarded with Blue Mountains fireflies. “There are about 30 species of firefly in Australia,” Spencer reveals. “A lot of people don’t know they exist here.” At other times of the year, it’s possible to spot native ghost fungi and bioluminescent bacteria, other treasures Spencer has discovered from spending lots of time in the canyon in the dark. “The bacteria are a really dull, milky-blue colour and the mushrooms are a yellowy-green,” he says.
Spencer plans to cultivate and incorporate them into his tours. May the light and beauty of his hidden, nocturnal kingdom never go out.