Rotorua: Waitomo Caves and Glow Worms

Although the Maori Cultural Institute was fascinating and an unexpected find, the real reason we came to Rotorua was to see the glow worms!

Beneath the wide Rotorua caldera, beneath all the geysers, boiling mud pools, and thermal pools, and beneath the hills at the rim of the caldera lie the Waitomo caves, an extensive network of limestone caves that started forming millions of years ago when New Zealand rose up out of the sea catching rainwater that then seeped down into the ground dissolving the limestone underneath and forming the caves.

We bought out tickets at the Blackwater Rafting Company. They provide tours of the caves, and for the more adventurous tourist, blackwater rafting on inner tubes with wet suits and helmets. We chose the walking tour.

The entrance to the Waitomo Cave complex.

Tim is standing in front of the actual cave we toured.

This was the entrance to our cave: a gently sloping lighted spiral walkway that reached 80 meters down into the cave.

At the bottom, we found beautiful formations of stalactites and stalagmites--all with a small river running through it.

Even more beautiful were the fan formations, undulating sheets of calcium deposits caused by dripping water.

Some beautifully back-lit fan formations.

And here is what we came to see: glow worms. They appear as tiny blue dots of light on the ceiling of the cave.

The are actually not worms. They are the larval stage of Fungus Gnats, a type of fly that spends its entire life in the caves. The adult female lays her eggs in clusters of 15-20 on the ceiling of the cave. The first larva that hatches eats all the other eggs in its cluster. So they begin their lives as cannibals.

Next the larvae begin to build a personal network of mucus tubes along the stone of the cave ceiling, and they spend the next nine months slithering around inside their collection of tubes dropping long, fine sticky threads (visible in the photo above) down into the air of the cave.

The feces of the larvae contains a bioluminescent chemical that oxidizes in the presence of an enzyme produced by the larva, causing the tails of the larvae to glow in the dark.

Aquatic-borne insects---mosquitoes, may flies, and others--that enter the cave or float into the cave as eggs and hatch there are attracted to the points of light on the cave ceiling. They think they are seeing stars that indicate a way out of the cave. As they fly toward the light, they become entangled in one of the sticky threads the larva has lowered from the ceiling.

Interestingly, the larvae can quickly sense when an insect has been caught, and in which of its many tubes. They quickly hoist up the tube and eat the poor insect alive. They then rapidly repair the tube and wait for the next unlucky flier.

The first worm photo above is from my camera, which doesn't adequately show the "worms." Here are a couple of photos from the Internet that show them better. This one shows a close-up of the glowing larva butts.

And this one shows the sticky thread traps hanging from the ceiling and waiting for hapless flying prey.

After nine months in the larval stage eating and feeding to store energy, the larvae spin themselves into a chrysalis for about 12 days and emerge as the adult Fungus Gnat. These adults have no mouths, so they cannot eat and rely completely on the energy from the food they conceived in the larval stage. The adults mate for 48 hours, after which the male dies. The female lives for 3 more days--just long enough to deposit hundreds of clusters of eggs on the cave ceiling, and then the life cycle starts all over again. All those months of work for a couple of days of crazy gnat-lovemaking, but no romantic dinners at all. Fascinating, but not much fun for the gnats!

At the end of our tour, our guide confessed to a little bit of false advertising. According to her, "Come see the glow worms" sounds much more interesting and attractive than "Come see the cannibalistic, carnivorous, slimy larvae with glowing butts that squeeze out sticky threads!" I would agree!

Onward through the caves we went. This is a vent rising high up through the cave ceiling.

Prior to the arrival of Europeans, the Maori people used the Waitomo cave system for shelter and as a sacred place of burial for their ancestors. Parts of the cave are sill off limits out of respect for the Maori burial sites.

And then we are back out into the daylight for a bit of lunch and a glass of delicious New Zealand sauvignon blanc before we head back to Rotorua.

After a rest, we took the Skyline Gondola from the floor of the caldera up to a peak above Lake Rotorua for dinner.

Cable car waiting for us to board.

A selfie on the way up!

Skyline Restaurant at the top of the gondola.

The restaurant featured an extensive buffet of all kinds of food and desserts. They didn't want me taking photos of their food, but I can tell you the green-lipped mussels in sweet chile-ginger sauce were the best!

I took this photo while we had a cocktail before dinner. Rotorua and the lake below in the setting sun.

And after dinner, a couple of nighttime shots of the city and the lake.

We've thoroughly enjoyed our time in Rotorua New Zealand. Tomorrow we drive back to Auckland to catch an Air New Zealand flight to Queenstown for a peek at the South Island.