How Rare Is It to See a Glow Worm?

Glow worms are not rare in New Zealand: the Department of Conservation (DOC) describes them as a feature of some cave systems, living wherever it is damp with little or no wind. What is rare is seeing a ceiling of them in total darkness, close enough to make out, without a torch spoiling it. Near Te Anau that view is inside the cave on the lake’s western shore, reached on RealNZ’s Te Anau: Glowworm Caves Guided Tour: 135 minutes from the lakefront, from US$72 a person, checked November 2026.

The calendar above is the Te Anau glow worm cave trip, with 3,176 reviews (checked November 2026). Departure times appear once you pick a date.

What a glow worm actually is

It is not a worm. DOC’s description: New Zealand glow worms, titiwai in Māori, Arachnocampa luminosa, are the larvae of small flies called fungus gnats. Only the larvae feed and only the larvae glow. Each one hangs sticky silk threads from its nest on the ceiling, and the light draws insects into them. A larva grows to about 2.5 cm before it turns into a pupa and then a fly.

Two more details: the light is a chemical reaction that gives off almost no heat, and a brighter glow means a hungrier larva: a well-fed one dims. And the adult fly cannot eat at all; it lives a few days, long enough to mate and lay eggs.

Why a cave makes them look like a night sky

Outside a cave, glow worms live on damp forest banks and overhangs, and the displays there are thinner. In a cave, two things change. There is no daylight, so the glow is all there is, and there is no wind, which the larvae need to keep their threads hanging straight. That is why a grotto can hold enough of them to read as a sky full of small stars. One October 2026 reviewer of the Te Anau trip put it as “pitch black where you can’t even see your hand in front of your face”; a September reviewer wrote that the glowworms “really do look like constellations in the night sky”.

Why there are no photos of your visit

Cameras are not allowed in the Te Anau cave, and photography and video are not permitted, to keep the glow worms visible for everyone: flash affects the larvae and undoes the time your eyes have spent adjusting to the dark. What you take home is what you saw, and the dark is the better for it: nobody’s screen lights up the grotto.

Check dates for the cave

What you see on the Te Anau trip

The cave part runs about 45 minutes, and about 200 metres of the system is open to visitors. Most of that is the walk in: steps, wet paths, rushing water, whirlpools and a roaring underground waterfall, in subdued light. The glow worms are at the end. The group steps into a small boat, talking stops, and the boat drifts into the grotto under the glow. Before or after, the displays at Cavern House show the larvae under light, which one reviewer found useful: “so you know what it actually looks like”.

The trip runs by day and in the evening all year, and since the cave is always dark, the glow worms show on any departure; an evening departure may cross the lake in the dark too.

Who will find it hard

• Children who cannot stay quiet. Part of the trip is silent; younger children are welcome, but it may not suit them. No minimum age is published; it is not suitable for infants.
• Anyone who cannot bend or manage steps. There is significant bending under a rock overhang at the entrance and steps throughout. It is not suitable for wheelchair users or people with mobility impairments.
• Anyone uneasy in the dark. The grotto is fully dark. One reviewer with that worry wrote that there were places to duck but “the space never felt too confined”.

Bring a warm layer for the 8 to 12 °C inside, a waterproof jacket and non-slip shoes. Is the cave rushed? goes through the reviews in more detail.