to Deal With Annoying Fungus Gnats
Fungus gnats are tiny flying insects that can be a problem for houseplants and greenhouse plants. Not only are fungus gnats annoying as they fly around, but they can also do some serious damage to plants.
It is the larvae of the fungus gnats that do the most damage. The adults live about a week, but during that time they lay hundreds of eggs in the soil of your potted plants. They are particularly attracted to damp soil that is rich in organic matter. Fungus gnat eggs hatch in four to six days, and for about the next two weeks the larvae feed on plant roots and root hairs in the soil. This can weaken the plants, stunting their growth and causing sudden wilting or yellowing of the leaves. In severe infestations plants may drop their leaves and new growth can be disfigured.
If you see fungus gnats flying around your plants, you can be sure that there are also larvae feeding on the roots of your plants. To monitor the fungus gnat population, use yellow sticky traps placed horizontally near the plants. Yellow sticky traps are available at many garden centers. Adult fungus gnats have poor flying skills, and as they flit about they will become stuck to the yellow sticky traps. The yellow sticky traps should be used only to monitor the population and should not be considered a means of controlling the population. They will not trap the larvae which are the real culprits.
If you suspect a plant is infested with fungus gnat larvae, you can tip the plant out of its pot and use a magnifying glass to examine the top inch or two of its soil. If fungus gnat larvae are present, you should be able to see the whitish or clear thread-like larvae near the soil surface.
Fungus gnats can also be easily controlled with a simple product you may already have at home. Fungus gnat larvae will die on contact with hydrogen peroxide. Be sure to use the ordinary 3% solution hydrogen peroxide with no added ingredients. First, allow the soil to dry out for a few days so the top two inches of soil is dry. This is where the larvae of fungus gnats reside, and they cannot survive in dry soil. During times of drought, the larvae will actually suspend their development, but once the soil is moist again, they will resume growing and eating.
Once the top layer of soil is dry, mix one part hydrogen peroxide with four parts water. Using this solution, water your plants as you normally would. The fungus gnat larvae will die on contact with the hydrogen peroxide, but the solution will not hurt your plants so long as it is mixed correctly. It would take an awful lot of hydrogen peroxide to harm the plants. When the hydrogen peroxide is watered in it will fizz a bit, but in a very short time it will naturally break down into nothing more than oxygen and water molecules which the plant will love.
by Michael J. McGroarty