Fungus gnats are completely harmless to plants but detrimental to our sanity. The only way to contain this issue is via nematodes. A biological pesticide that is healthier for your soil, plants and the environment.
The best way to combat these critters is to first understand their life cycle. Fruit flies start in the soil. Once the soil is hydrated the fruit fly eggs will hatch.
Gnat Free Potting Soil
https://gardeningincanada.net/testing-soil-microbes/That means step one to fruit fly prevention is choosing a good quality potting soil or going with a soilless approach. A good quality potting soil will not be void of fruit fly eggs but it will have less. In fact, we don’t want a “sterile” soil because this means we will not have the microbes needed to do basic processes, such as nutrient cycling. Try reusing potting soil that you have inoculated with nematodes or beneficial microbes.
Go Soilless– LECA
The other option is to go soil-less. This would involve trying a semi hydroponic setup with LECA or something such as sphagnum Moss with bark. Many tropical indoor plants actually thrive off of this setup. The reason for this is that many tropical plants are epiphytes. Meaning they naturally grow on the bark and moss of large trees.
A soilless setup will help bring them more in line with their natural habitat. The perfect mix of air, moisture and nutrients for their unique roots. This is the perfect solution for anyone who dislikes fruit flys and is a notorious over-watering plant parent.
Kill The Adult Fungus Gnats
Once the fruit flies have decided to set up shop in the house the first step is sticky traps. The goal is to catch all the adult bugs that could potentially lay eggs. Regardless of what treatment you choose this is an absolute must.
Take Out The Fungus Gnat Eggs
The second and ultimately the only solution you should use after that is something called nematodes. It’s less scary than it sounds I promise. Nematodes are microscopic critters that have been doing the heavy lifting in soils for millions of years.
Nematodes will simply eat all the fungus gnats’ eggs while you sleep. Within a few days, you will have no more fungus gnats and nematodes with a belly full of food. This method is considered a biological control method and is going to be the way of the future.
Why Pesticides & Mosquito Dunks Should Be The Last Resort
When we use things such as mosquito dunks (which work) or we try homemade soap and alcohol mixtures we do more harm than good. While on the surface everything seems fine on a microscopic level it looks like an extinction.
Homemade pesticides organic or otherwise are unbiased when it comes to taking out the problem. Things such as beneficial soil microbes involved in nutrient cycling, mites that keep leaves pest free & even tiny structures on the plants themselves such as the stomata can be harmed.
When we damage any portion of the natural organic systems within the soil and surrounding area of the plant we are setting back our progress. To avoid this try nematodes and sticky traps.
Does Hydrogen Peroxide Remove Fungus Gnats?
Hydrogen peroxide can help to serialize a soil and this includes the gnat eggs that reside in it. However, a sterile soil is also a soil that does not effectively nutrient cycle. There are better solutions than hydrogen peroxide for fungus gnats such as nematodes and BT.
Keep in mind hydrogen peroxide we get from the pharmacy has stabilizers such as silver. Silver can be toxic to plants even in low quantities. This means that plants continuously treated with hydrogen peroxide can suffer over time.
Homemade Sprays For Fungus Gnat Control?
Homemade sprays for fungus gnats will only control the adult gnats. This means the soil and all the larva in that soil are going to show up within a matter of time. The best way to treat fungus gnats is not with a homemade spray but rather by treating the source which is the soil.
Fungus Gnats & Cinnamon
Cinnamon can be used to treat some soil issues as it is an anti-bacterial and anti-fungal. However, cinnamon is not effective at treating fungus gnats. This is because fungus gnat larva is an insect and not a bacteria or fungi. Keep in mind cinnamon in all use cases needs to be fresh and authentic to even work.
In summary, ensure you are taking care of your soil and plants with the use of biological deterrents such as nematodes. These are friendly for both children and pets. They have no smell and you will hardly know they exist.