Arachnocampa luminosa is a species of fungus gnat which are, in their larval stage, glowworms. They are found mostly in New Zealand and Australia in caves and grottos, or sheltered places in forests.
The larva spins a nest out of silk on the ceiling of the cave and then hangs down as many as 70 threads of silk from around the nest, each up to 30 or 40 cm long and holding small droplets of mucus that act asa sticky glue. Prey fly into the strands of silk and the larva pulls it up (at up to about 2 millimetres a second) and feeds. In some species, the droplets of mucus on the silk threads are poisonous enhancing the trap’s ability to suppress prey quickly.
The larva glows to attract prey into its 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. Prey include midges, mayflies, caddis flies, mosquitos, moths, or even small snails or millipedes.