How To Get Rid of Gnats in Houseplants

If you own houseplants, odds are you've dealt with houseplant pests of some kind at one point or another. And if you haven't, well, don't get too comfortable because it is likely to happen sooner than later. Today we are going to focus on fungus gnats in houseplants and how to get rid of them.

What Are Different Types of Gnats in Houseplants?

There are several different types of flying bugs that you could find in your houseplants, some being more harmful than others. To help you know exactly what you are dealing with, here are the four most common winged houseplant pests you may find around your home.

1. Fungus Gnats

Fungus gnats are potentially the most common houseplant pest to find in your home. They are tiny black insects that are usually found buzzing around your houseplants. They are usually pretty harmless, though fungus gnat larvae do feed on the roots of houseplants, so large populations that are not controlled can become harmful to young or weak houseplants. Fungus gnats have a very short lifespan, though they multiply rapidly and easily spread from plant to plant. They love laying their eggs in moist soil, so it is most common to see them around your tropical plants or around plants with moist soil. If a houseplant is heavily infested with fungus gnats, you may be able to spot some of the small, white, and slightly translucent larvae crawling around through the soil. If this is the case, you will want to repot and treat your plant right away to keep the larvae from doing any damage.

2. Fruit Flies

Fruit flies are similar in size to fungus gnats, though they are slightly more round in shape and have a red-ish color to them. Fruit flies are not generally considered a houseplant pest because they are not usually attracted to houseplants. Regardless, they can sometimes be mistaken for fungus gnats if you aren't familiar with the differences, which is why we are mentioning them here. Fruit flies are most often seen hanging out in your kitchen around any fresh fruit you may have sitting out on the counter, near your trash bin, and the like. You will likely not see them hovering around your houseplants or crawling through the soil of your potted plants, but they can multiply quickly and become a real nuisance in your home if not handled right away. Set out apple cider vinegar and wash any fruit you bring home thoroughly to help keep any fruit fly populations at bay.

3. Whiteflies

As the name suggests, these are tiny little flies that are white in color. They are similar in size to fungus gnats and fruit flies, though they cause more damage. They like to live on the undersides of leaves and lay their eggs here. It is here that adult whitelies and their larvae will feed on the leaves of your plant. Unmanaged populations can be detrimental to your houseplants as they will feed on the foliage of your houseplants until there is nothing left to feed on and the plant dies. This houseplant pest can also spread easily since they are winged insects, making it all the more important to catch them early and treat any plants immediately.

4. Aphids

Aphids are most often found on outdoor plants, though it is not uncommon to see them indoors on your houseplants too. Adult aphids also have wings and are similar in size to the above-mentioned houseplant pests, though they can vary in color. Many are light green and blend in with the leaves of your plant, making them easy to miss. They also hang out on the bottom sides of leaves and feed on the leaves of your plant until the leaves shrivel up and die. Aphids can cause a lot of damage and can spread easily from plant to plant if not noticed early on and treated right away.

What Causes Gnats in Houseplants?

Now that we know what fungus gnats are, how to spot them, and the differences between fungus gnats and other houseplant pests, let's talk about how your plants can get infested with fungus gnats. To help you avoid getting them in the first place, we are going to talk about where they come from and what to look for to make sure you do not accidentally bring them into your home.

Infested Soil From the Store

It is very common for soil that you buy at the store to be infested with fungus gnats. Bagged soil is often stored outside where fungus gnats can easily get into the soil to lay their eggs. Even if you buy bagged soil that appears to have been stored indoors, that bag of soil was likely outdoors at one point and easily could have become infested with fungus gnats. It is all too easy to repot a plant with soil that was just bought from the store and unknowingly bring fungus gnat larvae into your home to infest all your other plants.

Our Recommendation: We recommend that no matter where you get your potting soil from, you check it before you use it to repot your plants. If you grab a bag at the store and notice little black gnats flying around the bag, choose a different bag. When you get home, open the bag and see if you can spot any gnats flying around on the inside of the bag. If the soil mix seems really moist, leave it outside in the sun to dry out. Fungus gnat larvae cannot survive in extremely dry conditions, so if there are any gnats in the soil, this will likely kill them off or drive them to search for a different, more moist home.

Bringing Home An Infested Plant

When you buy a new plant, that plant could very easily already be infested with fungus gnats, regardless of whether you get your plants from department stores or local garden centers. While it is easier to get pests from department stores than it is from local garden centers that do regular pest prevention, there is no way to prevent 100% of all pests at all times when hundreds of plants are kept in an indoor space at one time. Plants can easily become infested when they are transported from suppliers to retailers or pests can get in from outside, and it is difficult, if not impossible to prevent them entirely.

Our Recommendation: We always recommend that you check a plant thoroughly before you purchase it. Check the soil, check the undersides of leaves, check along the stems, and if you notice any pests at all, you may want to let an employee know so the plant can be quarantines and then choose a different plant. It is also never a bad idea to treat a newly purchased plant for pests immediately after bringing it home, regardless of whether or not pests appear to be present. Taking this precautionary measure can save you much time, energy, money, frustration, and heartbreak in the event that the plant was infested and you just didn't realize it.

Putting Your Plants Outside During the Summer Months

Some people like to put their houseplants outdoors during the warm summer months. While this can help them grow strong and healthy with the additional warmth and sunlight, it also leaves them much more exposed to any pest that may come along. Then when the weather starts to cool down and plants are brought inside for the winter, any houseplant pests that may have made a home on your houseplant or in the soil are brought indoors as well.

Our Recommendation: If you are a person who likes to put your plants outside on nice days or for extended periods of time, we always recommend quarantining that plant when you bring it back indoors and treating it for pests even if none are visible at the moment. Keeping the plant away from any other plants for two weeks will help to keep any pests that could be hiding in the foliage of your plant from spreading before you notice them. If you choose to treat your plants as a preventative measure, this quarantine time will also give the pest control products of your choice time to work.

Bugs Getting Inside Your Home

It is actually easier than you would think for a fungus gnat or any other houseplant pest for that matter to get into your home. Whether they find their way in through a window or sneak in when you open the front door, they are not shy and will come right in and make themselves at home.

Our Recommendation: Unfortunately, there is not much you can do to keep bugs from getting inside your home. Fortunately though, this is probably one of the least common ways to get pests in your houseplants. Making sure your screens are in good condition and trying not to leave any doors open unnecessarily will be the best way to keep unwanted pests from entering your home and infesting your plants.

Do Fungus Gnats Harm Houseplants?

Fungus gnats are often more of an annoyance than they are a real threat. They do feed on the roots of your houseplants, but fungus gnat populations do not usually get large enough to do real damage to your plants. If you do begin to notice fungus gnats in your home though, you will want to do something about it sooner than later though so the population of gnats does not get out of control. Large populations of fungus gnats can have negative effects on young or weak plants, so just be sure to not let a small population grow to a full-blown infestation.

5 Ways To Get Rid of Gnats in Houseplants

If you are wondering how to get rid of gnats in houseplants, the answer is usually a two-part process. There are adult fungus gnats that fly around, and then there are fungus gnat larvae that live in the soil of our houseplants until they become adult gnats. It will be important to kill the larvae in the soil so they do not become adults, and it is equally important to kill the adults so they cannot lay more eggs. Here are some ways to get rid of both the larvae and adult gnats in houseplants.

1. Use Mosquito Bits to Kill Fungus Gnat Larvae

Mosquito Bits is a product that can be used to kill the larvae of fungus gnats. It works on mosquito larvae and fungus gnat larvae alike. This biological larvae control is fast-acting, killing larvae in minutes, and is also not toxic to humans or pets. You can dissolve the granules in water and use this "tea" to water any infested plants, or you can sprinkle the granules over the soil. Granules can also be mixed into your potting mix prior to planting as a preventative measure. Learn more about Mosquito Bits and purchase online today!

2. Use Sticky Traps to Kill Adults Fungus Gnats

Sticky Traps are great for catching adult fungus gnats. There are a number of different types of sticky traps, though they usually consist of a stake with a sticky surface attached that gets placed at the base of an infested plant. The sticky parts of the traps are often yellow, which is a color intended to attract the fungus gnats. The gnats will fly around and land on the sticky trap, getting stuck and dying there. This may not capture all adult fungus gnats, but it will get as many of them as possible and will help you avoid having to run around the house trying to smack them out of the air like a crazy person!

3. Use Vinegar to Kill Adult Fungus Gnats

Adult fungus gnats are also attracted to vinegar, so placing a small cup of apple cider vinegar at the base of a plant or near a group of infested plants can attract them to the vinegar. They will attempt to land and drink the vinegar and will end up drowning in the liquid. This technique may not be quite as effective as using sticky traps, as not every adult gnat may choose to land in the vinegar, but it will at least help to diminish the adult population.

4. Apply a Top Layer of Gravel or Decorative Rocks

Adding a top layer of gravel or decorative rocks can act as a deterrent, as adult fungus gnats may not find the top layer as an appealing place to lay their eggs. While this may work better as a preventative measure, it is something that you can try to discourage the spread of fungus gnats to your other plants.

5. Allow the Soil to Dry Out

As we said above, fungus gnats need a nice, moist environment to lay their eggs in. Soil that remains moist will be particularly attractive to fungus gnats. If you notice a lot of gnats hanging out around one plant, try to avoid watering that plant and let the soil dry out as much as you can without causing harm to the houseplant. This may help to deter any adults from laying more eggs in the soil by making it an inhospitable environment.

How To Get Rid of Fungus Gnats in Houseplants

If you have more questions or have tried all of the above-mentioned tactics for getting rid of fungus gnats to no avail, let us know. We are happy to answer all questions and are here to help you with any houseplant pest problems you may be having. If you want to learn more about houseplant pests, we have several very helpful videos on our YouTube channel detailing different types of pests and how to treat your houseplants! Check out that video below and feel free to contact us any time with questions.