Soil Gnats
A common plant pest is the soil gnat (aka fungus gnats). They are very small and look very similar to fruit flys but they are a darker color. They are usually noticed walking on the soil or flying around the infested plant and nearby windows. They like humidity, moisture and rich damp soil. Sometimes they come in from outside or are in the potting soil already, it’s hard to know exactly. The adults are harmless but annoying. The larva feeding in the soil however can damage the roots.
To know how to treat an infested plant, you have to understand a soil gnats life cycle. Their full life cycle is roughly a month long. An adult soil gnat can lay up to 300 eggs in its lifespan and they live about 1 week. 4-6 days after the eggs have been laid, the larvae emerge. They grow for 2 weeks eating organic matter in the soil. Once they have reached maximum size there is a 3-4 day pupal phase. They then emerge as adults and the cycle begins again.
The best pest control is prevention. Always closely inspect the plant before purchasing. Quarantine any new plants for 2-3 weeks once you bring them home. This helps prevent any pests spreading to your other houseplants. Be careful not to overwater, especially during the winter months. Soggy soil is ideal for soil gnat eggs. If you do see pests, treat the infested plant as soon as possible. Let the top 2 inches of soil dry out between waterings. This kills any larva, stops egg development and makes the soil less attractive to egg laying females.
There are many products to treat soil gnats and many that work. I have had success with this natural treatment and it is gentle enough for the plant but very effective at killing the gnats, eggs and larva.
Items Needed:
-3% hydrogen peroxide
-water
-spray bottle
-chopstick or any tool that can aerate the soil
Carefully aerate the soil with the tool.
Prepare the solution. Mix a 1:1 ratio of water and hydrogen peroxide in the spray bottle.
Liberally spray the solution directly to the soil of the infested plant.
Reapply the solution once the soil completely dries out, about once a week.
Continue treating until you no longer see gnats. 2-4 applications should be enough.
Another great method of treatment is to simply discard ALL the infested soil.
Remove the plant from the pot and rinse all the soil off the roots.
Wash the pot with hot water and spray it with the hydrogen peroxide mixture.
Repot the plant in new soil.
Repeat whichever of these treatment plans you choose weekly until the infestation is gone.
There are many other pesticides and treatments if these don’t work but they can be harmful to the plants, animals and people so use them with caution and carefully follow the directions.