Insects · Diptera · Keroplatidae

Fungus Gnat

Arachnocampa luminosa

Not Evaluated

It has not yet been assessed against the IUCN criteria. See full glossary

A fungus gnat endemic to New Zealand whose larva is bioluminescent and lives on the roof of limestone caves and damp gorges. It hangs dozens of silk lines coated in sticky droplets and emits a blue-green light that draws insects into the trap.

Size

1 cm – 4 cm

Lifespan

1 years

Diet

Carnivore

Feeds mainly on other animals.

Activity

Nocturnal

Active mainly at night.

Social structure

Colony

Lives in large concentrations, often for breeding reasons.

Sighting difficulty

Unknown

Temperate forestCarnivore Nocturnal Colonial Insect Temperate forest

1countries 8parks

Fun facts

GeneralIts larvae light the Waitomo caves blue and hunt with sticky threads of silk.
The larva regulates its glow according to how hungry it is: the longer it goes unfed, the brighter its light.
The adult has no functional mouthparts: it lives barely a few days, solely to breed, and dies without eating.
It is not a firefly but the larva of a fungus gnat, and it is endemic to New Zealand; its genus exists only there and in Australia.
It fishes with lines. It weaves a silk nest on the cave ceiling and hangs up to thirty threads from it, dotted with droplets of sticky mucus. The blue-green light attracts flying insects, which get caught in the threads, and the larva hauls them up by swallowing the thread itself.
The hungrier it is, the brighter it glows: well-fed larvae dim their light and hungry ones intensify it to attract more prey. The most impressive displays in the caves are, in reality, larvae going hungry.
It is territorial and cannibalistic: if two nests end up too close together there are fights, and mature larvae keep about 10 or 15 cm apart.
The adult lives a very short time: about 76 hours for the female and about 96 for the male. It does not eat, has no functional mouthparts, and its only task is to reproduce.
The Waitomo caves came to receive up to half a million visitors a year, and their climate is actively managed: in the 1970s an open entrance turned the cave into a wind tunnel and damaged the colony.