Glow-worm display spectacular
One evening recently a group of boy scouts visiting Nicols Creek was privileged to see the 17m high waterfall illuminated misty white by the light of myriads of glow-worms occupying the surrounding walls.
Nicols Creek is a shady bush streamlet that formerly entered the water of Leith just above Woodhaugh, Dunedin.
The water is very pure and is piped at the lower end and connected to the Dunedin water supply.
A short way into the valley the streamlet drops over four large waterfalls. The first is pretty and quite spectacular – a sheer drop over a high moss-green wall of rock surrounded by native forest.
After dark there is a spectacular and beautiful display of glow-worms on the walls of the first gorge. Glow-worms also occur in fewer numbers within sight of the falls. (The large numbers present during our recent visit was unusual).
Last century, this waterfall was one of New Zealand’s better-known scenic attractions. Today it is virtually forgotten. This is a good thing in some ways because it has enabled the native vegetation to revert to almost its former condition.
The light in the glow-worm Arachnocampa luminosa, is produced in the tail of a legless fly larva. The larva lives inside a flexible tube to which are suspended 20 to 40 threads strung with sticky globules that resemble a string of beads. These are “fishing lines”. Small flying insects such as gnats, attracted to the glow-worm’s light, bump into the hanging threads and get caught.
When it feels the tug, the glow-worm glides along its tube to the relevant line and quickly draws it in. It eats the insect rapidly.
Glow-worm eggs are small and spherical. The larva emits a bright light immediately after it hatches from the egg. It finds a place to build a tubular nest, then lets down sticky fishing lines. After about nine months when it is 30mm long, it changes into a pupa. The pupal period lasts from 12 to 13 days. All stages except the egg can glow.
– Nature file, Otago Museum, Anthony Harris, 16/5/1994. Newspaper cutting.