What is "fungus gnat"

1. n. minute blackish gregarious flies destructive to mushrooms and seedlings [syn: sciara, sciarid]

2. mosquito-like insect whose larvae feed on fungi or decaying vegetation

Fungus gnats (some times mistakenly identified as drain flies) are small, dark, short-lived gnats, of the families Sciaridae, Diadocidiidae, Ditomyiidae, Keroplatidae, Bolitophilidae, and Mycetophilidae (order Diptera); they are sometimes placed in the superfamily Mycetophilidae.