If you've noticed tiny, dark insects flying around your houseplants, you likely have fungus gnats. These tiny flies can be a nuisance indoors and may also damage your plants.
Fungus gnats lay their eggs in moist soil and their larvae feed on plant roots and decaying organic matter. Because of this, the key to managing fungus gnats is to let the soil dry out in between watering and don't overwater plants. Water plants from the bottom using saucers under pots. This keeps the top of the soil dry, discouraging fungus gnats.
Sticky traps can be placed in pots or near plants to catch fungus gnat adults. This is also a great way to monitor for fungus gnats. Pesticides, including several biological pesticides like Bacillus thuringiensis subspecies israelensis (Bti), are available to control fungus gnats. However, the best way to control fungus gnats is by simply adjusting watering practices.
To learn more about fungus gnats and their management, visit Pest Notes: Fungus Gnats.
This article first appeared in the UC Integrated Pest Management Program's Pests in the Urban Landscape blog.