New Zealand, Waitomo: Glow-in-the-Dark Cave Worms

The only reason we added Waitomo to our itinerary in New Zealand was to see some glowworms. The worms we saw were unique to New Zealand, of the Arachnocampa Luminosa (the Latin translates as "spider-like, light-producing larva") species. That species of glowworms goes through a life cycle of eggs hatching to larvae then pupating to an adult fly. They spend most of their life as larvae, and only the larvae "glow".

The glowworm lifecycle isn't very long. The initial larval stage lasts about 6 to 12 months, depending on food. The larva emerges from the egg only about 3 to 5 millimetres long, and through its life grows about 3 centimetres to the shape and size of a matchstick. The larva spins a nest out of silk on the ceiling of the cave and then hangs down as many as 70 threads of silk (called snares) from around the nest, each up to 30 or 40 cm long and holding droplets of mucus. The larvae can only live in a place out of the wind, to stop their lines being tangled, hence caves, overhangs or deep rainforest are the best place to find them. Note that the silk nest and snares are very similar to a spider's web, so you can start understanding why the Latin classification name had been given.

Seeing the glowworms all over the ceiling of the cave emitting their tiny beams of light was something that neither of us will ever forget

Now that you understand the "spider-like" part of their species name, the "light-producing" phenomenon needs to be explained. The larva glows to attract prey into its sticky threads. The glowworm prey includes midges, mayflies, caddis flies, mosquitoes, moths, or even small snails or millipedes. When prey is caught by a line, the larva pulls it up (at up to about 2 millimetres a second) and devours it. If prey is scarce, the larvae will turn to cannibalism, eating other larvae, pupae or adult flies. The glow is the result of a chemical reaction that involves a waste product, an enzyme that acts upon that waste, energy and oxygen; the reaction occurs in modified excretory organs known as Malpighian tubules in the abdomen.

At the end of the larva stage, it becomes a pupa, hanging down from the roof of the cave. The pupa stage lasts about 1 or 2 weeks and it glows intermittently. The male stops glowing a few days before emerging, the female's glow increases; when the flies emerge from the pupas, the adults look like large mosquitoes. The glow from the female is believed to be to attract a mate, and males may be waiting there when she emerges, ready for action. The adults (of both sexes) have no mouths and, therefore, cannot feed; they live only a short time, around 2-3 days. They glow, but only intermittently, and their sole purpose is to mate, and for the female to lay eggs. Adult insects are poor fliers and so will often remain in the same area, building a colony of glowworms. The female lays a total of about 130 small spherical eggs and dies soon after laying. The larvae hatch after about 20 days and the cycle repeats itself.

To survive, the glowworms require a special habitat: humidity to prevent them from drying out, sheltered surfaces to hang from and suspend their sticky, spider-like feeding lines, calm atmospheres to prevent their lines from tangling, darkness to allow their light to attract food, and a plentiful supply of insects to eat. The caves at Waitomo provide a perfect setting for the glowworms and it was one of the best places in New Zealand to see the unique insects, so we were excited during the drive there from Rotorua. We were so keen on getting to the caves that we woke especially early to complete the long drive to Waitomo, which was near the west coast of the North Island. Many other travellers we had spoken to mentioned that the glowworms were amazing and we had a mental picture in our heads as to what we were going to see that day.

Breakfast in our campervan was a bowl of cereal with milk for each of us, and tea that we made from some tea bags we had nicked (that's the same as stole for the Americans reading this) from the Sofitel Tahiti Resort where we had stayed on the island of Tahiti a few weeks earlier. We didn't really steal the tea bags; they were complimentary in our room. We could understand why the tea was complimentary because it tasted awful, like some kind of chemically processed flowers, something we would have been better off cleaning the toilet with instead of drinking! We dumped that tea out and made a fresh pot using some English Breakfast tea bags that we had nicked a few days earlier from the holiday park where we stayed in Auckland. Those tea bags we did take, as they were lying out in the open on the kitchen counter for the entire world to see.

Along the way, we had to fill Bessie (our beloved campervan) up with petrol, which gave us another excuse to buy a fantastic New Zealand meat pie. We made it a habit that anytime we filled up our vehicle with petrol, we would buy a meat pie to share. The pies only cost a few New Zealand Dollars (around £1, or $2 USD), and they were really tasty. During the drive, we were once again blessed with blue skies as we passed fantastic views of green, rugged, rolling hills dotted with sheep and other animals (mostly cows if there weren't sheep, but sometimes we saw deer). Upon arriving at Waitomo, we pulled into the information centre car park opposite the ticket office, where we would buy our tickets to go on one of the glowworm cave guided tours.

Before buying our tickets, we made lunch. The drive took us around three hours and we were both peckish (that's the same as hungry for the Americans reading this) when we arrived, so we made tortilla wraps filled with lemon and black pepper tuna, cheese and mayonnaise. The food gave us the energy we needed to climb the very steep road leading out of the car park, the same steep road on which Kyle would stall the campervan a few times before finally driving away after our cave tour. When we purchased our tickets, a huge group of (noisy) schoolchildren, who looked to be within the 10-12 age range, came up behind us, and we thought to ourselves that it would be awful if they were on our tour.

As luck would have it, they weren't on our tour. While their teachers were sorting out their entrance tickets, we sat down outside the cave entrance, waiting for our tour guide to take us and about 15 other people inside. During our short wait, we learned some more interesting facts about the area and the caves. Waitomo meant "water entering a hole in the ground" in the Maori language and, over the last 24 million years, the Waitomo landscape has been shaped by faulting, earthquakes and volcanic eruptions. The limestone layers in the region were pushed up from the sea floor, buckled and broken. Cracks and joints separating the huge blocks allowed water to flow between them, gradually dissolving and carving out the caves that exist today. Local Maori people had long known of the existence of the caves in the Waitomo region; however, they chose not to reveal their secret until 1887, when chief Tane Tinorau was persuaded to explore the Waitomo Glowworm Caves by an English surveyor, Fred Mace. Government surveyors later mapped the cave and by 1889 the cave had opened to visitors.

Nowadays, people (that's us!) are able to visit the caves and enjoy many of the great adventure activities on offer like rock climbing, cave tubing or even abseiling down the deep dark shafts (not us! we went for the cheaper option of walking through a cave). However, it is also one of the best places to observe the incredible glowworms, which was the main reason we had come to the region. The other activities did look really fun, but our meagre travel budget for the country meant that we had to pick and choose our activities wisely. Of course, if you read about our Zorb and Shweeb activities in our last journal entry for Rotorua, you would know that we didn't always choose wisely!

Our guide in the cave was a young local man who was very informative and interesting to listen to, even when he cracked a few jokes that sometimes - not always - made the group laugh. The glowworm cave was much smaller compared to the caves we had seen earlier on our travels this year (remember the enormous caves we told you about in Borneo?), but it was still impressive with its many stalactites and stalagmites. At the far end of the cave system, there was a set of steps leading to a pool filled with water from an underground river. Above the fresh water pool, on the low cave ceiling, were several hundred larvae that had put down their snares, or lines, to capture prey and feed on them.

What lay before us then was very interesting, seeing hundreds of short pieces of string hanging from the cave with sticky substances on the lines trapping insects before they are drawn up and then devoured. To avoid human interference with the mystical creatures, we weren't allowed to get close enough to actually see any of the pulling up or devouring activities, but we let our imaginations run wild with the image. After a few minutes observing the glowworms there, our guide took us back through the cave to the other side. There were many other guides with small groups being led around the cave at the same time, so we felt a little bit like herded cattle, as we were only allowed to stay at one location for a certain period of time before moving on somewhere else.

At one of our stops in the cave, in the main chamber, our guide explained the acoustics within the chamber and asked if anybody in our group would like to test them out by singing a song. An older German man ended up being (heavily) pressured by his family into singing something since he was a member of a choir back in his home town. He ended up singing a German song for a couple of minutes whilst we all listened to the acoustics of the cave, not really enjoying the song at all and treating it more as a scientific experiment rather than an enjoyable presentation.

The last part of our tour was definitely the best part. We waited to board a boat that took us through some of the cave passages along the underground river. During the boat journey, we saw the largest concentration of glowworms on the ceiling above us, and the luminous creatures lit up the cave enough to not require any other form of light; it was like looking up at the clearest night sky ever with millions of bright stars above us. There was a silence rule as we rode the boat through the cave, but some of the Chinese tourists on our boat hadn't understood that part of the tour explanation. It was okay, though, because they understood when we turned around and firmly said "Shhhhhhh". We had been separated from the rest of our tour group and put onto a Chinese tour boat because there were a couple of extra spaces, and we felt like we were back on the boat from Guilin to Yangshuo, in China, when we were the only non-Chinese tourists travelling down the Li River with a boat full of over 100 Chinese tourists.

The boat journey along the underground river was controlled by the guides pulling on a rope system using their hands and arms; using powered boats would have scared the glowworms since they like quiet spaces. Plus, it wouldn't have made the journey through the cave as pleasant with a loud motor running. The boat journey was short but we saw what we had gone there to see. The only disappointing thing was that photos were not permitted inside the cave where the glowworms lived, even without a flash. Seeing the glowworms all over the ceiling of the cave emitting their tiny beams of light was something that neither of us will ever forget, another beautiful and incredible thing of nature.

The boat ride ended outside of the cave and we disembarked and headed up a small hill towards the exit, where we walked across the street to the information centre car park. Our overall feeling about the tour was good, but that it was probably more expensive than it should have been, at $39 New Zealand Dollars per ticket (that's around £15, or $30 USD, each). However, we did see the glowworms in the only place in the world where it was possible to do so, and the benefit outweighed the cost that time. When we drove out the car park, once Kyle had gotten the whole clutch-accelerator-brake thing sorted out during Dan's yelling fits at him for stalling the car on a hill and rolling back towards parked vehicles, we went for a coffee at The Black Cafe to relax before driving on to Tongariro National Park, our next stop in the North Island. The reason we chose that cafe was because we were offered free cookies with the purchase of coffees there if we presented our cave entrance ticket; the cookies were delicious!

After spending some quality time at the cafe, we drove from Waitomo to Tongariro. The weather clouded up during the drive and there were dark, heavy clouds blocking our view of the mountains. We anticipated the worst but were very happy with Mother Nature the next morning when we woke up. You need to read the next journal entry when we post it, so you understand how good she was being to us in New Zealand. Even though it was dark when we arrived at the national park, we had driven above the dark and gloomy clouds and could see a snow-capped mountain glistening in the moonlight. It was exciting to see our first snow-capped mountain of many in the country!

The Whakapapa Holiday Park was situated a few metres down the road from the information centre inside Whakapapa Village. We stayed there and had a nice meal of pasta and New Zealand white wine in our campervan before turning in for the night. The holiday park was really nice and surrounded by native New Zealand bush, so we felt like we were truly camping out for the evening.