How do I get rid of fungus gnats in houseplant soil?

Fungus gnats breed in constantly moist organic soil. Allow the top 2 inches to dry, remove fallen debris on the surface, and top-dress with a thin layer of sand to discourage egg laying.

Yellow sticky traps catch adults; Bacillus thuringiensis var. israelensis (BTI) or nematodes target larvae. Avoid over-fertilizing, which keeps soil wet longer.