4 Incredible glowworm facts you won’t know

Date: 7 May 2024

If you’re planning a road trip around New Zealand, you’ve probably noticed that there are things called glowworm caves. Depending on where you’re from, glowworms may seem like a strange concept, but they’re fascinating creatures that can create the most magical environments. Glowworms can even provide the perfect lighting for a romantic date. So before you go off to find them, learn a little about them first with these 4 glowworm facts we reckon you won’t know, but will blow your mind!

1. Glowworms are not actually worms

They’re larvae of fungus gnats, an insect that looks like a mosquito. There are two types of fungus gnats – those that feed on fungi like mushrooms, and those that are carnivorous and feed on other smaller insects. The glowworms in New Zealand and Australia are the larvae of the carnivorous fungus gnats, and our NZ glowworms even eat each other in some cases!

2. Glowworms are bioluminescent

This means they produce and emit light naturally from an organ near their tails that is like a human kidney. The bioluminescence is created through a reaction of an enzyme called luciferase and a variety of other chemicals that cause this natural, blue-green glow. The chemicals and enzymes from their bodies are reacting with oxygen in the air to create light. There is a sac surrounding the light organ that provides oxygen and helps concentrate the reflection of the light.

Beyond being pretty to look at, the bioluminescent glow is also used to attract prey. Smaller insects and flies are drawn to the light and fly towards it, and the glowworms have their dinner sorted!

3. Glowworms prey on smaller insects such as mayflies, midges, moths, and flies

While glowworms are rather small, about the size of a matchstick, to capture their food, they have to build a network of silk threads that hang vertically from their habitat that are covered in a sticky mucus. Their prey are drawn to their glowing bioluminescent light and fly towards it, into the sticky silk maze, where they get stuck for glowworms to eat – similar to how spiders capture their prey in webs.

Adult glowworm flies (fungus gnats) never get caught in these sticky webs because they aren’t attracted to the light; plus, they are strong enough to pull away from the threads.

An up close shot of glowworms hanging from the cave, shining bright blue in the darkness

4. The species of glowworm that can be found in New Zealand is called Arachnocampa luminosa.

They most commonly live in caves, forests and other sheltered, damp areas. The most popular glowworm caves in New Zealand are in Te Anau and Waitomo. In a cave environment, the bioluminescent glowing can happen during both day and night due to the darkness. The dark habitats are also ideal for glowworms to thrive because of little wind and dampness enough for prey to be present. There are hundreds of glowworms in the Te Anau caves that collectively glitter like stars to create a magical and unforgettable experience.

This species of glowworm, the Arachnocampa luminosa, can only be found in New Zealand and parts of Australia. Glowworms in other parts of the world refer to beetles, rather than larvae, making our glowworms unique. Don’t miss this special opportunity to see the best of nature.