Dish detergent powers grease and dried food off your dishes. In a pinch, it can help get chocolate stains out of clothing. And if you are dealing with irritating tiny gnats flying around your houseplants, you can use dish detergent to kill the adults and start the process of ending the infestation.
Gnats are a common issue in houseplants. They enter your home through windows or hitch a ride on new plants with infected soil. Fungus gnats are the most widespread problem. The winged adults swarm around plants and congregate around windows and lamps. They don’t bite, so they aren’t a danger to your family. Their larvae can be dangerous for plants. They live in the soil of infected plants, feeding on fungal matter. If they can’t find enough fungus, they will eat the roots of your plant. This can cause it to wilt.
Dish detergent kills a variety of insects, including gnats in houseplants. The liquid dishwashing detergent in your kitchen contains surfactants. These compounds allow detergent to penetrate oils and organic matter and lift stains and clear away mess. The surfactants also help detergent to penetrate an insect’s soft body. Once the detergent is inside the gnat, it poisons and kills it.
To use dish detergent to kill gnats, all you need is a plastic spray bottle. Pour a teaspoon or two of detergent into the bottle, then fill it the rest of the way with water. Shake it well to distribute the detergent throughout the entire mixture. Aim the spray at the gnats in your kitchen or those hanging around your windows. You can spray the gnats on your plant directly. After you spray them, wait 10 minutes, then wipe up any liquid and gnat bodies you see.
While dish detergent kills adult gnats, it won’t do anything about the larvae living in the soil. This means even if you kill all the adults, in a week or two you will have a new generation flying around your home. Fungus gnat larvae can be drowned. Fill a large bucket with water. Submerge the infected plant’s pot in the water for five seconds, then pull it out. To avoid mess, this is best performed outdoors. Leave the plant outside until the soil dries. If you don’t see any new gnats around it, bring it back into your home.
- “How to Be Successful With Houseplants From the Plant's Perspective”; Jane Perry; 2007
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