Glowworms are a must-see when you come to New Zealand. They are such a beautiful sight on their own, and tours like the Footwhistle Glowworm Tour take you deep into otherwise unseen parts of the country. Unlike many other Glowworm tours, at Caveworld you can get up close and personal with these unique and fascinating insects. So what exactly are you looking at?
1. What are Glowworms?
The Glowworms that you will see in your tour of the Footwhistle cave are a species of gnat called Arachnocampa luminosa which are only found in New Zealand and Australia. The adult Arachnocampa are a type of flying gnat, and what you come to see are the larve form. These maggot-looking larvae cluster together and although they are most spectacular in caves, glowworms are also quite common outside – they can be found wherever conditions are damp, food is in good supply and there is an overhanging wall. It is not uncommon to find them on trees and cliffs overhanging rivers in many parts of the country, although these are not always easy to access.
2. What makes Glowworms glow?
The New Zealand glowworm is one of many creatures that naturally produce light in a process called bioluminescence. This is similar to the other glowing life that comes to mind including deep-sea fish mushrooms and plankton.
The light is the result of a chemical reaction that involves several components that react with oxygen to create the famous blue light. While the lights that you will see in the cave come from the larvae, the gnats do glow as well – though not as brightly.
3. Why do Glowworms glow?
The glowworms’ light is part of their hunting behaviour. Because they live in such dark places including Footwhistle Cave, insects are drawn to the glowing light. The glowworms spin sticky threads that hang from the roof of the cave and trap any flying insects that get too close to the light. Glowworms are carnivorous, meaning they only eat other insects, and their appealing glow and clever traps makes them very successful hunters! If a glowworm is hungry its light will shine a little brighter and is even more effective.
4. Why do Glowworms live in caves?
Glowworms love caves because they are perfect hunting-grounds. Because their method of catching prey needs dark and sheltered areas, caves like Footwhistle are perfect. The natural darkness of being underground means that the glowworms can hunt around the clock, and protection from wind and rain keeps the sticky silken traps from breaking or becoming tangled. Glowworms also require a lot of insects to eat, and the streams and still water found in caves offer a perfect breeding ground for these.