How to Get Rid of Gnats From House Plants


Fungus gnats (Bradysia sp.) are small insects that resemble fruit flies and are attracted to moist soil. Although adult fungus gnats won't harm your houseplants, the larvae feed on root hairs and can stunt plant growth. The insects develop in potting soil, according to entomologists with Colorado State University, and any plant can become a host.

Step 1

Limit soil moisture by allowing the surface of the soil to dry out prior to watering.

Step 2

Avoid fertilizing with manure, bloodmeal or other organic fertilizers, as these serve to attract fungus gnats.

Step 3

Control the fungus gnat larvae by drenching the soil with the biological insecticide Bacillus thuringiensis, the H-14 strain. Specialists at Colorado State University mention that commercially available pesticides, such as Gnatrol and Knock-Out Gnats, contain this substance.

Things You'll Need

  • Insecticide


  • University of Minnesota: Houseplant Insect Control
  • Colorado State University Extension: Managing Houseplant Pests
  • University of California, Davis: Fungus Gnats, Shore Flies, Moth Flies, and March Flies
Keywords: houseplant fungus gnats, fungus gnats houseplant, control fungus gnats

About this Author

Victoria Hunter, a former broadcaster and real estate agent, has provided audio and written services to both small businesses and large corporations, worldwide. Hunter is a freelance writer specializing in the real estate industry. She devotes her spare time to her other passions: gardening and cooking. Hunter holds a Bachelor of Arts in English/creative writing.