Removing Gnats on an Indoor Potted Plant

Gnats can infest potted plants.

If you notice tiny insects flying around your indoor plants, the plants are being attacked by fungus gnats. Fungus gnats are 1/8 inch in size and look like tiny mosquitoes. Fungus gnats often appear because of too much watering. They thrive in moist conditions. Although fungus gnats do not bite humans or pets, these gnats will destroy the roots of your indoor plants if they are not controlled.

Things You'll Need

• Yellow sticky traps
• Bacillus thuringiensissubsp israelensis (BTI)
• Insecticidal spray

Instructions

1. Allow the soil of your indoor plants to dry up a little before you water them again. You need to get rid of the condition that is attracting the gnats.

2. Set some yellow sticky traps from your local hardware store over the soil of your indoor plants. Make sure the sticky side is facing up. When the trap is full, throw it away and replace it with a new trap.

3. Add Bacillus thuringiensissubsp israelensis (BTI) to your potting soil. This is an all-natural insecticide that will get rid of the fungus-gnat larvae before they hatch.

4. Use an insecticidal spray containing the active ingredient permethrin. This will take care of any adults that are still flying around your indoor plants.

Tips & Warnings

• You can determine if fungus gnat larvae are present by setting slices of potatoes over your potting soil. Wait a few days and turn the potato slice over. If there are any gnat larvae, you'll see them.

• Instead of adding BTI to your soil, you can add beneficial nematodes. Nematodes are tiny roundworms that will eat the larvae of your fungus gnats.

• Make sure the gnats do not have an entry point in to your house. That may mean adding some caulk to your doors and windows.

References

• Colorado State University: Fungus Gnats as Houseplant and Indoor Pests
• North Carolina Cooperative Extension: Fungus Gnats Indoors
• University of Minnesota: FAQ: Fungus Gnats