How to Remove Fungus Gnats

This post will cover what adult fungus gnats look like, what symptoms to look for, as well as how to get rid of them from the soil surface of your houseplants.

Fungus gnats are houseplant pests that are usually tiny, black flies with long legs and fairly long antenna. They are mostly harmless and they look like mosquitoes. They are usually found in accumulated organic matter, which could be on the surface of the soil or around the base of plants. Adult gnats are about 4-6 mm in length and have slender bodies. They have light grey wings with dark streaks.

Fungus gnat larvae are white and worm-like and are about 3-5 mm long when they reach maturity. They have small blackheads and lack legs. 

Why Fungus Gnats Are Attracted to Your Plants

Fungus gnats are typically attracted to the moisture in your potting mix in your soil. Amazingly enough, a small fungus gnat infestation won’t typically cause damage to your plant. This doesn’t mean you shouldn’t act. Not only can the insects be incredibly annoying, but if their numbers grow, they can cause a lot of damage to your plant roots. 

There are several symptoms of fungus gnats that you can look for on your plants. Noticing these signs will alert you to take quick action to lower the chance of additional fungus gnat populations in your home. Here are a few of the things you can watch out for:

1. Yellowing or Wilting Leaves

   If you notice sudden wilting on your plant or yellowing leaves, it may be that the gnats have begun to hurt your plant. 

2. Weakening Plant

   Large pest populations can cause your plant to weaken. Without proper care, your plant could eventually die.

3. Poor Growth

   Unfortunately, these pesky gnats can cause your plant to experience slower growth. You will need to remove them in order to help your plant thrive. 

Once you have identified the pests on your plant, you will need to try to remove them. It is important to act quickly as this infestation is typically one of the most difficult ones to fight. Here is what you need to do in order to remove the gnats from your plants:

1. STEP 1

   Quarantine any infected plants as soon as you can. You may want to also move neighboring plants to another area in your home in case they are also infected to prevent further spread.

2. STEP 2

   Remove the top inch of soil from the plant and replace it. Make sure that you properly dispose of the soil and don’t reuse it. This will hopefully remove most of the eggs and larvae in your container. Replace it with an inch of sand or gravel, which don’t contain the organic materials the pests need in order to thrive. 

3. STEP 3

   Allow the top part of your soil to dry out. Gnats in the larval stages require moist soil in order to survive. Making sure that the top inch of soil is dry can help minimize the effects. Water the plant from the bottom if possible. 

4. STEP 4

   Create a soap and water mixture by mixing a cup of water with a few drops of dish soap. Carefully spray the top of the soil to help kill any larvae that remain. Repeat the process every couple of days. 

5. STEP 5

   Lay down sticky traps on both the soil and around the plant. As the pesky fungus gnats move around, many of them will get stuck. Replace the sticky traps every few days until the problem goes away. 

When to Destroy/Get Rid of Your Plant

At some point, you may realize that you will need to prune most of your plant in order to get rid of the damage or you can’t seem to get rid of the adult flies no matter what you try, you may need to destroy or get rid of your plant.

If you live in an area where they can live outside, you may be able to set them out on your patio (so long as there are no other plants nearby that they can harm) and introduce one of their predators to feed on them. 

While there is no way to completely prevent some pests from entering your home, there are a few things you can do to help keep your potted plants safe. Try the following to prevent these adult flies from finding and colonizing your home:

1. Quarantine plants as they enter your home

   Regardless if you get your plants online or from local garden centers, you may unknowingly bring home pests. Even if you don’t see fungus gnat adults on it when you purchase it, it could have eggs its damp soil that may hatch at a later date. For this reason, it is a good idea to quarantine your plants for 10 – 14 days after you bring it home to protect your other houseplants.  

2. Water from the bottom of the plant

   These gnats tend to affect the top inches of soil. Whether you have African violets or another plant, it may be a good idea to keep the top part of your soil dry to help prevent another infestation in your indoor garden. 

3. Keep spare potting soil dry

   Many of us keep additional rich soil in our garages or greenhouses. Unfortunately, if the soil gets moist, it can attract these unwanted pests. Instead, find a closed container that you can use to store your extra soil and peat moss. 

4. Don’t overwater your plants

   Not only can overwatering your plants cause root rot, it could also attract these annoying pests. Make sure that your pots have a drainage hole so that the top inch of the soil will dry out a little faster (if it is good for the plant).