Waitomo glowworm caves - New Zealand

Mosquito-sized glow worms, Arachnocampa luminosa

These glowworms are a species of fungus gnat endemic to New Zealand. Both the larval stage and the Imago are luminescent. The species is known to dwell in wet caves, grottoes and sheltered, humid places in forests. Its Māori name is titiwai, meaning "projected over water".

The species' life cycle starts with an egg, which hatches into a larva and then pupates into an adult fly.  At the end of the larva stage it becomes a pupa, hanging down from the roof of the cave on a short, silken thread. The pupa stage lasts about 1 or 2 weeks and it glows intermittently. The male almost stops glowing a few days before emerging, the female's glow increases. The glow from the female is believed to be to attract a mate, and males may be waiting there when she emerges. Adult New Zealand Glowworms do not feed and live only a few days. Both males and females glow, but not as bright as larvae. The sole purpose of the adults is to mate, and for the female to lay eggs. Adult insects are poor fliers and so will often remain in the same area, building a colony of glowworms. The female lays a total of about 130 eggs, in clumps of 40 or 50, and dies soon after laying. The eggs hatch after about 20 days and the cycle repeats.

Larvae glow to attract prey into their threads, perhaps luring them into believing they are outdoors, for the roof of a cave covered with larva can look remarkably like a starry sky at night. A hungry larva glows brighter than one which has just eaten. Prey include midgesmayfliescaddis fliesmosquitosmoths, or even small snailsor millipedes. When prey is entangled in a snare, the larva pulls it up by ingesting the snare and starts feeding.