Fungus gnats have another common name of "dark-winged fungus gnats.  They don't bite and are common on over-watered soil. The adult do not feed. Fungus gnats adults are tiny flies one-eighth inch or less in length. They have a dark, slender body and compared to more typical flies such as house flies, fungus gnats have long, dark antennae. The wings are dark, to light gray in color, giving one common and abundant group the The larvae feed on decaying or damaged roots.They do not damage plants and are considered to be only nuisances.To control them, don't over water houseplants. Wash of the tomatoes before you eat them.