FUNGUS GNAT

also called mushroom fly any member of the insect families Mycetophilidae and Sciaridae (order Diptera), small mosquito-like flies with maggots (larvae) that feed on fungi. In Sciaridae, the dark-winged fungus gnat family, the eyes of the adults almost touch and the wings are usually dusky. The creamy-white or gray larvae of the genus Sciara may travel in armies, migrating in snakelike lines 1 cm (0.4 inch) deep in search of food or when ready to enter a resting stage (pupa). Some species of Sciara and some mycetophilids attack mushroom beds, sometimes completely destroying them; S. tritici damages the roots of wheat. The family Mycetophilidae contains a few injurious species. The wingless adult female Pnyxia scabiei bores into potato tubers and causes scabs. Platyura larvae are predatory, feeding on small insects and worms that are killed by oxalic acid secreted on the loose, slimy webs that the larvae secrete. Larvae of several species are luminous: Arachnocampa luminosa lights caves in New Zealand. It spins webs with hanging sticky strands to catch flying insects for food.