Fungus gnats are very small flies 1/32 to 7/16-inch long, slender to robust, long-legged and mosquito like. They are usually black, brown or yellowish. The dark winged fungus gnat has smoke colored wings, and he other fungus gnats have spots on their wings. The larvae are inconspicuous although they have well-developed heads, 11 to 12 body segments, and a ventral bottom lobe on their last abdominal segment.
The dark winged fungus gnats molt four times as a larva. The other fungus gnats lay their eggs directly on larval food. The eggs hatch in a few days, and the larvae molt five times in six to eight days. They pupate in the ground and the adults emerge in three days.
The larval food consists of moist decaying organic matter and fungi growing in soil. These gnats breed in various settings, such as rotting wood, animal waste, under bark, in over-watered plants and their saucers, and atriums. Flat-roof structures and accumulated droppings in bird cages are potential breeding sites.