Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Hexapoda
Class: Insecta
Subclass: Pterygota
Infraclass: Neoptera
Superorder: Endopterygota
Order: Diptera
Suborder: Nematocera
Infraorder: Bibionomorpha
Superfamily: Sciaroidea
Family: Mycetophilidae
Common name: Fungus gnats, Predatory Fungus Gnats.

Mycetophilidae is a family of very small flies (Some of larger ones can grow up to 0.7cm) which look a lot like mosquitoes, forming the bulk of those species known as fungus gnats. There are approximately 3000 described species in 150 genera but the true number of species is undoubtedly much higher. They are generally found in the damp habitats favoured by their host fungi and sometimes form dense swarms.
Their bodies are brown or grey or yellowish, depending on the species. They all have one pair of clear wings and a hairy thorax. Adults of this family can usually be separated from other small flies by the strongly humped thorax but identification within the family between genera and species generally requires a close study of microscopic features. The terrestrial larvae usually feed on fungi, especially the spores and hyphae, but some species have been recorded on mosses and liverworts. The larvae of some species, while still being associated with fungi, are at least partly predatory. Adults do not bite or feed.
Around a dozen mycetophilid species are unique among flies in displaying bioluminescence. In some species, this is restricted to the larval stage but in others, this feature is retained by the pupae and adults.

A 4mm body length gnat.
Fungus Gnats Family Mycetophilidae -001.JPG

Fungus Gnats Family Mycetophilidae .JPG

Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0