Diptera: Sciaridae, Excechia nugatoria.
The Fungus Gnats are tiny pests that belong to a family of flies called Fungivoridae and Sciaridae. Most species are black in color and very small (less than 1/16 inch) in size, although a few species may reach 1/4 inch long. Key identifying characteristics include long legs and long thin wings. Adult Fungus Gnats prefer to lay their eggs in moist potting soil, which is why buildings containing potted plants or atriums. Soon after the eggs are laid, the larvae emerge to feed on fungus growing in damp potting soil.