How to Kill House Gnats With Pesticides

Gnats are small, two-winged flying insects that typically appear as large groups. They can be a nuisance to humans, and some types of gnats have the ability to bite. Pesticides are not required to get rid of most gnats; removal of waste products and moist organic matter along with proper screening of doors and windows should be enough. However, large infestations of gnats ̵2; particularly certain species like fungus gnats ̵2; may require pesticide treatment to dispose of them.

Things You'll Need

  • Bacillus thuringiensis pesticide
  • Pyrethrin-based pesticide
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Instructions

    • 1

      Locate the source of your gnat problem. Indoors, gnats are normally drawn to rotting organic matter. Fungus gnats will also be drawn to potted plants to lay eggs in the soil. You can tell if you have fungus gnats because they will be near potted plants, range from 1/16- to 1/8-inch in size, have clear or gray-colored wings and hardly fly. Other gnats will vary in color and size, but are normally around 1/16-inch in size and commonly fly in large swarms.

    • 2

      Use pesticides with Bacillus thuringiensis as the active ingredient to control fungus gnats. This pesticide can be found online or at a hardware store. Spray your potted plants with it to kill fungus gnats and larvae on your plants. This type of pesticide is not harmful to your plants, other animals and most beneficial insects. If used properly, the gnats should be killed within a day. This pesticide wears off plants quickly, often in a day or two, meaning multiple sprayings may be required.

    • 3

      Spray a pyrethrin-based pesticide to kill other types of gnats. Also, you may use pyrethrins for fungus gnats if Bacillus thuringiensis is not available. Pyrethrin pesticide can be purchased online or at a hardware store. Pyrethrins have a low toxicity level for humans and pets, but will kill beneficial insects in addition to gnats. Spray indoor or outdoor areas and see results almost immediately.