Fungus gnats are small, dark-winged insects commonly found in damp soil, particularly in houseplants and greenhouses. They are about 1/8 inch long and are often mistaken for fruit flies. The larvae feed on organic matter and plant roots, which can harm young plants and seedlings. These pests thrive in moist environments, making overwatered plants a prime target. To control fungus gnats, it's essential to allow the soil to dry out between waterings and use sticky traps to catch adult flies. Reducing humidity and improving drainage can also help prevent infestations.