How to Get Rid of Gnats in Indoor Plants Naturally
Yikes! Wondering where those fly-like pests in your house are coming from? Do a few fly away every time you water or mist a certain plant? It’s likely fungus gnats. While the name sounds gross, these non-biting bugs aren’t that bad when compared to their common houseplant pest counterparts. Fungus gnats are a low concern as long as the problem is treated quickly and efficiently to prevent infestation. These pesky insects are fairly easy to get rid of with these 4 natural, at-home steps below.
What are fungus gnats?
These particular gnats are tiny and dark with a short life span. But don’t let that deter you from getting rid of them quickly as these insects reproduce and multiply rapidly (with up to 200 eggs each!). So it’s best to act as soon as you spot them.
Where do they come from?
Before we jump into how to eliminate fungus gnats, it’s important to understand where they live so that we can properly treat a plant without harming it in the process. These pesky gnats can originate from a few different sources-- they could simply fly in from outside or transfer from one plant to another. Although often confused as fruit flies, fungus gnats do not come from drains or feed on sugary produce. These gnats instead are attracted to fungus, decaying organic matter, like moist soil. They lay eggs in the damp soil which hatch into larva and feed on the soil and often the roots of the plant. At the adult stage, the gnats fly and hover around the top layer of the soil to feed. They can also venture off into other areas of the home looking for moisture (and perhaps another damp plant’s soil to call home).
How do we eradicate them?
Step 1: Dry Out Soil
Since fungus gnats thrive on moisture, the first and easiest step is to allow the soil of the plant to dry out between waterings. An overwatered plant, especially one with standing water, provides a prime location for gnats to live and reproduce.
Step 2: Replace Soil
If allowing the soil to dry out a bit doesn’t seem to work, the next step is to replace the top layer of soil (about two inches deep) with fresh, sterile potting soil. There’s also the option to replace a thin layer of soil with sand (from a garden center) which will help cut down the gnat population while also further drying out the soil.
The new layer of soil (or sand) will remove eggs, larva, pupa, and some gnats, deterring new hatchlings and new growth. Even though you have fresh soil, still remember to go lightly with watering-- because without moisture, the gnats will be unable to survive.
Step 3: Natural Insecticidal Spray
If you have a bigger infestation of fungus gnats or the above steps didn’t show some results within 2 weeks, try the trusty ole soapy water mixture. This go-to remedy works for many plant pests as a natural insecticidal spray. Simply mix a liquid soap (we prefer Dr. Bronner’s castile soap) with water in a spray bottle at a ratio of 1 tablespoon soap per 1-quart water. Spray the soil to saturate the top layer. (Tip: It’s always best to test an area first to make sure the soapy mixture is compatible with your plant).
Step 4: Sticky Tape Trap
Another option is to try sticky tape, a popular and effective mechanism of ridding of the adult gnats quickly. Pictured above is a sticky wand which works well, but sheets of a similar yellow adhesive are believed to work best. The weak-flyers are attracted to the color yellow and fly right onto the tape where they’re trapped indefinitely. If the gnats did lay eggs, you will need to keep a sheet of tape up for about a month (while also keeping the soil mostly dry) to eliminate the entire colony.
Of note: An adult fungus gnat typically only lives for about a week, but its total life span (from egg stage) lasts around a month. Keep this lifecycle in mind when ridding your plant and home from fungus gnats, as it may take a full month to see complete results.
The only true harm that fungus gnats pose is to the plant roots which larvae enjoy feeding on. If there are enough larvae, this harm to the root system can cause irreversible damage, killing your plant. Although a nuisance, fungus gnats are harmless to humans and animals as they cannot bite and carry no known human diseases.
Prevention of fungus gnats:
The bottom line is to remember to care for your plants properly to ensure health and longevity. To avoid pesky little fungus gnats, don’t overwater your plants. It may be helpful to water from the bottom tray so that the top layer of soil isn’t saturated. BUT don’t leave the plant pan sitting with water-- it could become a breeding ground for insects!
We’ve found that a combination of all of the methods above works best (aka quickest) to eliminate these gnats. Persistence is key as it may take some time to completely eradicate fungus gnats. Simple, easy, affordable, and natural, you will safely and effectively be living pest-free in no time (well, ok, maybe 1-4 weeks)!