Rid your home of Fungus Gnats

Updated August 01, 2019
Rid your home of Fungus Gnats

Some of you can relate: You’ve noticed little, annoying insects flying around your indoor and outdoor potted plants or planters and wondering what they are? It could be fungus gnats. They’re tiny flies that are attracted to pots and planters because they like to breed, feed and live in soil that is constantly moist and high in organic materials. Their larvae hatch in just a few days, eventually lead to infestation and ultimately damage to your plants.

Because their ideal temperature to thrive is about 75 degrees, fungus gnats can thrive indoors any time of year. If you grow plants or seedlings indoors on a patio or in a green house, fungus gnats may show up very soon after planting.

Thankfully, controlling fungus gnats is manageable. Things to consider when trying to control these pesky insects:

  • Spraying or fogging synthetic insecticides to control adult fungus gnats is not effective and is a waste of time, money and dangerous to you and the environment. You can use yellow sticky traps if needed.

  • Indoor and outdoor fungus gnat infestations can be partially controlled by letting the soil dry out between watering cycles. Make sure your potted plants are well-drained. Controlling the larvae will eliminate the flying adults.

  • Adding beneficial nematodes, which only feed on certain larvae and do not bother earthworms or cause any danger to plants, humans or pets. Beneficial nematodes are readily available in nurseries. They are sold in a package that is kept in the refrigerator until use.

  • Use Bti products. This insecticide/biologic option is a naturally occurring bacterium that only kills the larvae of mosquitoes, black flies and fungus gnats. Bti is packaged as a dry material and placed into water or on soil. All the nurseries and big box stores carry Bti products. Make sure you read and follow the label application instructions.

For other useful, environmentally friendly pest management tips, visit http://ipm.ucanr.edu.

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