A network of limestone caves whose ceilings are covered with thousands of Arachnocampa luminosa — glowworms endemic to New Zealand that produce a steady blue-green bioluminescent light, transforming cave ceilings into the night sky.
Arachnocampa luminosa is not a worm. It is the larval stage of a fungus gnat found only in New Zealand. The larvae live on cave ceilings, suspended from the rock by mucus threads. They produce bioluminescence — a steady, blue-green light — that attracts other insects, which fly toward it and become entangled in sticky threads the larvae have hung below themselves. In the Waitomo Caves, thousands of these larvae live on limestone ceilings that formed 30 million years ago. From the flat-bottomed boats that drift silently through the caves with motors off, the ceiling appears to be the night sky. Each larva is a star. In some chambers the density is comparable to a clear night away from city lights. The ceiling is curved like a dome. The water reflects it from below. In the silence and the dark, the disorientation between underground and outside, between ceiling and sky, becomes complete. The Maori who knew these caves called the glowworm Te Toro o te Rangi — the searching light of heaven.