Glowworms are the larval stage in the life of an insect called the fungus gnat. The scientific name of the New Zealand species is Arachnocampa luminosa. Similar glowworms can be found in the south-east of Australia.
The New Zealand glowworm is one of many creatures that naturally produce light (bioluminescence). The light is the result of a chemical reaction that involves several components: luciferin, luciferase, adenosine triphosphate and oxygen. These combine to form a product capable of emitting a blue-green light.
The light is used to attract insects, brought into the cave in the rivers, which the glowworm catches and eats. If a glowworm is hungry its light will shine a little brighter and is even more effective. When the female glowworm reaches the adult stage the light is used to attract males for mating.
The larva is the only stage of the life cycle at which the species eats - as an adult it has no mouth. To feed, the glowworm hangs down dozens of sticky threads which are used to trap any insects which fly towards the light. When an insect is caught in the threads, the glowworm senses the vibrations and hauls in its victim - at the same time chemicals in the thread paralyze the insect.
