Fungus gnats often frequent potted plants where they lay their eggs in the soil, dine on the plants' roots as larvae and cause a nuisance as adults.

Caring for outdoor potted plants can kick up a swarm in the form of fungus gnats that commonly develop to maturity in the plants' growing medium. And when your customers bring those plants indoors, the pests can infest the soil of other houseplants.

Moist potting soil is a prime habitation for fungus gnats who lay their eggs there, and as larvae, can damage the plant by eating its roots. After about two to three weeks, the maggots pupate into adults.

Letting the soil dry out between waterings reportedly helps to control them but brings with it inherent dangers to the plant. A more aggressive, yet still natural, approach is to treat the plants with an organic horticultural oil such as Summit® Year-Round® Spray Oil. OMRI listed® and approved for use in certified organic production, the oil blocks the adult gnats', and other insects', breathing holes, which makes them suffocate. It is designed to be mild enough to be used on plant buds and shoots, and sensitive plants. Also there is no known build-up of resistance by the insects to horticultural oil sprays.