Fungus gnats are a nuisance that often comes into your home on a new house plant. Thankfully they don’t do much damage beyond being annoying and unsightly. They can harm young plants or seedlings, but for most mature plants having them will only slow their growth and not much else. The good news is that they can be avoided and are pretty easy to get rid of once you learn a little about them.
So what are Fungus Gnats? Fungus gnats are pesky bugs that often invade your houseplants. They look like tiny mosquitos with black heads, clear wings, and thin legs. They are usually sized about 1/8” long. Fruit flies are slightly smaller, rounder, with stubbier legs, and are often more orange rather than black. You will likely find fruit flies coming in from rotting fruit and hovering in your kitchen. If you pull your plant out of its pot, you will likely see the large in the soil as the larvae eat the small roots on a plant and other organic material (think dead leaves). The Fungus Gnats only live for about a week, but in that time, they are proficient (like fruit flies) at reproducing and can lay up to 300 eggs. In nature, they break down organic material. I often see them in my compost bin doing their job. They lay their eggs in the top inch of damp soil and the cycle starts again.
Choose your plan of action to get rid of Fungus Gnats
1. Change your watering schedule
Most people over water rather than underwater their houseplants. Fungus Gnats (and fruit flies) need moisture. Stop watering your plants for a few weeks and let the top of the soil dry out. Only water when the top two inches of the soil is dry. Not only will it stop the gnats, but it will also be healthier for your plant.
In combination with that, choose planters with a drainage hole to prevent water from accumulating in your planter. Also if the plant is in the bathroom, there may be too much humidity. Consider removing your plant to a different room to see if that helps.
2. Prune and clean up your houseplants
Take some time and trim dead leave and remove the organic debris from the soil that the gnats use as food. This also has the added benefit of making your plant look nicer.
3. Use Sticky Traps to kill existing Gnats
This won’t prevent them in the future much, but it might help with the current ick factor used in combination with the other things on this list. You can make your own sticky track using strong double-sided tape and placing it on the inside and outside of your infected plants. You can also buy sticky traps from garden stores or online from Amazon that work well.
4. Create a gnat and fruit fly trap for existing pests
This free version is quick and effective. Take a jar or even a glass that you have. Fill the bottom inch with vinegar (I also like adding a few pieces of fruit to the bottom). take a piece of paper and make a cone with a small hole in the bottom. Both fungus gnats and fruit flys can be captured this way. They go in but can’t figure out how to get out and eventually drown.
5. Dress your plant up with gravel or decorative rocks
Fungus gnats are looking for a moist environment. Combing a reduced watering schedule with decorative rocks can help a lot. Adding up to an inch of rocks on top of your soil keeps a dry layer at the base of the plant where gnats normally lay their eggs. Decorative rocks have the added benefit of dressing up your planter to give it a more finished look. Dressing your plant with rocks also prevents the gnat’s larvae from climbing out of the soil and prevents them from maturing. Make sure to pack it in well. The larvae will die trapped beneath, and you should be pest-free within a day or so.
5. Spray those Gnats
Another quick solution that is great to combine with longer-term preventative measures, is to spray Fungus Gnats. A homemade solution of water and soap can be used to spray on the top layer of soil. For those not inclined to concoct a solution, the same effects can be had by using a Neem oil solution spray that you can purchase online or in your local garden center. This natural treatment is safe to use inside the home and after a few treatments should rid you of those pesky gnats.
