Fungus gnats (Bradysia spp.) are a common houseplant pest. Though they only measure 1/8 inch long, they can become quite a nuisance when present in large swarms. The bugs' entire lifespan centers around your houseplant and your houseplant's soil. Use cultural, manual and chemical controls to get rid of the gnats and preserve your houseplant's health and beauty.
Remove dead leaves and other organic matter on the surface of the pot. Such matter serves as food for the developing gnat larvae.
Decrease the amount of water you provide your houseplants. The gnat eggs and larvae thrive in moist soil. Colorado State University recommends allowing the top 2 inches of the potting soil to dry out between watering sessions to kill the eggs and baby gnats.
Hang yellow sticky traps on the outer branches of your houseplant. These traps attract the gnats, which then get stuck to the trap surfaces and die, according to the University of Minnesota. The university says yellow traps attract not only gnats, but other common houseplant pests like whiteflies and flying aphids.
Move the houseplants to a well-ventilated area like an outdoor porch and spray the plants with an insecticide. The University of Minnesota recommends using an gnat-targeting insecticide formulated with Bacillus thuringiensis. Spray both the plant itself and the soil surface to kill any developing gnats.