The ultimate bait-and-switch artist of the insect world has a secret. When you see that ethereal, blue-green luminescence in a cave, you are not looking at a worm or even a firefly. You are looking at the bioluminescent waste product of a carnivorous fungus gnat larva. It is essentially a hungry maggot with a glowing bottom. The light is produced by a chemical reaction in its excretory organs, the Malpighian tubules, and its sole purpose is to trick other insects into flying towards what they think is the moon or the open sky, only to find themselves entangled in a lethal, sticky trap. The engineering behind a titiwai colony is both elegant and revolting. Each larva builds a nest of silk and mucus on the ceiling and then lets down up to thirty vertical fishing lines. These lines are made of silk and dotted with droplets of incredibly strong, acidic mucus that look like a string of pearls. An unsuspecting moth or midge, drawn to the blue glow, flies into these lines and is instantly snagged. The glowworm then reels in the line by swallowing it, silk, glue, prey and all, digesting the victim while it is still fresh. If a line gets tangled or a neighbour gets too close, they are not above a bit of cannibalism to keep the prime real estate clear. The lifecycle of the glowworm is a masterclass in lopsided evolution. The larval stage, the one that does all the glowing and eating, can last for up to a year. During this time, it is a sedentary predator, focusing entirely on accumulating mass. Once it pupates and emerges as an adult fly, the party is over. The adult Arachnocampa luminosa has no mouthparts. It cannot eat. It exists for only a few days with one singular mission: to find a mate, lay eggs back in the colony, and then die of starvation. It is a frantic, short-lived finale to a year spent in a slow, glowing trance. What makes the New Zealand species so iconic is its sheer scale. In the limestone caves of the King Country, millions of these larvae create a light show so bright it can be used to navigate a boat. They are highly sensitive to their environment. If you shine a torch on them or talk too loudly, they douse their lights, retreating into a protective chemical sulk that can last for hours. They are the un-flies, the creatures that turned a dark, damp cave into a high-stakes art gallery. To see them is to realise that in New Zealand, even the maggots are trying to be stars.