The Life Cycle of a Glow Worm
The spherical eggs (0.75mm in diameter) are usually deposited directly onto the cave wall. Upon hatching, the cylindrical larva immediately begins to glow. When they first emerge they are usually between 3 and 5 millimeters long, and will grow to between 30 and 40mm across several months. The larvae may move around on the surface of the cave or bank before selecting a site to begin producing its silk nest.[2] Most larvae emerge during the spring.[9]
The larva spins a nest out of silk on the ceiling of the cave and then hangs down up to 30 silk threads along which it regularly places small sticky droplets.[10] Their prey largely include other small Diptera (especially midges)[9] although glowworm living on banks may also trap spiders and other non-flying invertebrates.[10] When prey is entangled in a snare, the larva pulls it up by ingesting the snare and starts feeding on the prey alive.[5]
After five larval instars,[9] the larva will suspend itself on a long thread and pupates over up to 24 hours. The pupal phase lasts about two weeks. During this time, the pupa continue to glow although males eventually lose their glow. The adults which eventually emerge are poor fliers.[2]Adults usually emerge during the winter and tend to live for up to 76 hours in the case of females and up to 96 hours in the case of males.[9]Females usually lay over 100 eggs and eggs usually hatch after about 20 days.[2]
Sources of mortality for glowworms include predation by cave harvestmen (including the short-legged harvestmen, Hendea myersi cavernicola, and the long-legged harvestmen, Megalopsalis tumida), parasitic fungi (Tolypocladium sp.), and possibly cannibalism when adults become entangled in other larvae's silk threads although evidence is mixed.[9][10]
Why do they glow?
The larvae of this species glow to attract prey into their threads
This glow is produced as a result a luciferase enzyme acting upon a small molecule of luciferin.[12] It occurs in modified excretory organs known as Malpighian tubules in the abdomen.[13] The luciferase enzyme in this species shares similarities with the protein that occurs in fireflies. However, the luciferin that the enzyme acts upon is entirely different to that of fireflies and, indeed, other currently known bioluminescent systems.[12]
Where Can I See the Glow Worms?
Hokitika Glow Worm Dell
Hokitika has the cutest little glow worm dell only a minutes walk from the highway. See the fairy-like lights at night. It is free and children just love it!
The Hokitika Glow Worm Dell is located right on the highway at the northern entrance to the town. There is a small parking area at the entrance with some interpretation boards for you to read. The dell is up a short bush walk that is suitable for strollers. This activity is a real favourite of all our guests, especially the children and best of all, it is FREE!
You can learn all about the glow worms of New Zealand
here: https://teara.govt.nz/en/glow-worms/page-1
When Should I Go?
The best time to view the glow worms is after dark. You will not see them glowing during the day time. The later you go, the less people there will be. It gets very busy during the busy summer tourist season. Be aware that not all visitors are considerate of others. Sometimes there are those that shine their torches in others eyes, are noisy and do not keep left while walking on the path. Also some try to use flash photography to capture an image of the glow - this does not work.
My Top Tips For An Enjoyable Visit.
Take a small torch or use the light on your cellphone. Keep it pointed down away from others.
Use low light camera settings - no flash!
Keep left going up and down the path. Hold the hand rail.
Hold your children's hands, don't let them run ahead for their safety and the enjoyment of others.
Do NOT touch the glow worms.
Visit after the sun has gone down. The later the better - less people.
Take care pulling into and out of the car park. ALWAYS use your indicator so other vehicles know which way you are going.