In the Waitomo Caves of New Zealand, the ceilings of some chambers look exactly like a starry sky. The “stars” are thousands of tiny glow-worms hanging from the rock, each one producing a soft blue-green light from a chemical reaction in its body.
These glow-worms aren’t really worms. They’re the larvae of a small fly that lives only in New Zealand. They dangle long sticky silk threads down from the ceiling like fishing lines, and use their glow to lure mosquitoes and other insects into the trap.
The caves themselves are limestone, about 30 million years old, carved out by rivers running through soft rock. Visitors drift through them on small boats in total darkness, with only the eerie blue-green glow above their heads for light.
