This article by Dr Chris Reid, of the Australian Museum, was first published in 2508 District News in June 2018.
I was asked to write about glowworms, because we have them locally in Helensburgh and they are a bit of a tourist thing. Let's say it's a can of worms.
Glowworms aren't worms at all, of course, they are fly maggots. They belong to a group of flies called fungus gnats, whose maggots feed on fungi. However, the maggots of our fungus gnats have gone from vegan to carnivore. To do that they use a light as a lure for small flying insects and produce a mesh of sticky threads to trap them. They don't just live in old railway tunnels, but these provide a perfect environment for them to form large spectacular colonies.
Technically, they are species of Arachnocampa (literally 'spun field'), a genus of eight species found in New Zealand and Australia, all of which have glowing maggots.
Our local species is unique to the area around Sydney – there are other species in Queensland, Victoria, Tasmania and New Zealand. Ours, Arachnocampa richardsae, was named in 1966 after a young scientist, Aola Richards, working as a researcher at the University of New South Wales. She was a keen caver and discovered the glowworms in the famous tunnel at Newnes. Aola went on to have a long career in entomology and continued to study cave-dwelling insects.
The adults are just boring little mosquito-like flies. They have no mouthparts, so they simply mate, lay eggs and die, within a few days. You basically won't see them unless you rear them from a maggot. The naming of species is almost always based on adults, not maggots, so it's important to have examples of the adult in collections. Here at the Australian Museum, we have the original specimen of Arachnocampa richardsae, the one on which the species is based.
Both the glow and the threads are produced from the maggot gut, using the proteins broken down from the insects it feeds on. The threads are apparently a sticky sort of urine.
There are several different teams of researchers studying the glowworms, based in several different countries. These teams might be 'bioprospecting' – looking for naturally occurring chemicals or phenomena that have industrial applications. For example, the generation of light without heat and the production of sticky threads from pee. So our little glowworms might be worth millions of dollars. Or not.
Even so, several basic things in the biology of our species are still unknown. For example: how do the adults avoid being trapped by the sticky threads? Which flying insects do the maggots feed on? When is their peak glowing? What feeds on the maggots? Perhaps local schools could look into this.
Another thing I discovered is that a zoo in Japan has imported our species for a popular glowworm tunnel display. Maybe that could be done here too.
This is just one species of fly. Australia has about 15,000 species. I wonder what the others do?
