While Arachnocampa luminosa may sound like the name of an intricate spell, it’s actually an insect that produces an enchanting effect completely on its own.

Better known as “glowworms”, these gnat larvae produce a distinctive blue-green light that illuminates New Zealand’s subterranean Waitomo glowworm caves. The tiny, star-like dots attract unsuspecting flies, mosquitoes and snails to their sticky, silk string nests, which stretch up to 40cm from the cave ceiling. Prey is fooled into thinking they are still under the night sky, a trick that is not hard to believe when looking up at the millions of luminescent creatures shimmering against a pitch black background. 

The caves were formed more than 30 million years ago on the North Island of New Zealand and were first explored in 1887 by a Maori chief and an English surveyor. The two built a raft of flax to float down the underground stream and discovered the “Glowworm Grotto” when they noticed bright lights reflecting on the water. (The insect’s Maori name is titiwai, meaning “reflected over water”.) By 1889, Maori Chief Tane Tinorau and his wife started leading tourists through the caves. New Zealand’s government took over the operation in 1906, but it was returned to Tinorau’s descendents in 1989.

Today, visitors can see the glowworms perform their magic, just as they did more than 100 years ago, on a 45-minute boat tour down the Waitomo River, through 250m of underground caverns.