How to Get Rid of Fungus Gnats in Cannabis

If you have a problem with fungus gnats in your cannabis, you’re not alone. These tiny pests are attracted to moist conditions and can quickly become a nuisance. But don’t worry, there are a few things you can do to get rid of them for good!

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Fungus Gnats

Fungus gnats are small, dark-colored insects that are attracted to the roots of plants. They are often found in damp, humid areas and can be a nuisance in homes and greenhouses. Fungus gnats can damage the roots of plants, which can lead to stunted growth or even death.

What are they?

Fungus gnats are small, dark-colored mosquitoes that are often found near areas of standing water. They lay their eggs in damp soil, where the larvae hatch and feed on fungi and other organic matter. These pests can be a nuisance in greenhouses and indoor gardens, as they can fly in through open doors and windows. In addition, the larvae can damage plant roots, which can lead to stunted growth or death. If you think you have a fungus gnat problem, there are several things you can do to get rid of them.

What do they do?

Fungus gnats are small, dark-colored insects that are often found near sources of moisture. The adults are rarely seen, but the larvae can be a serious problem for cannabis growers.

These pests feed on the roots of plants, which can damage the plant and reduce its ability to take up water and nutrients. In severe cases, fungus gnats can kill a plant.

Fungus gnats are also vectors for diseases that can affect both plants and humans. These diseases can be difficult to control and can potentially destroy an entire crop.

Why are they bad for your plants?

Fungus gnats are more than just a nuisance; they can actually damage your plants. The larvae of these insects feed on the roots of seedlings and young plants, which can stunt the plant’s growth or even kill it. In addition, the larvae carries a bacterium called Erwinia carotovora, which can cause plant diseases such as root rot. Even if the larvae don’t kill your plants, they can still spread this bacteria to healthy plants.

Getting Rid of Fungus Gnats

Most cannabis growers will eventually have to deal with fungus gnats. These small flying insects are attracted to the moist soil of potted plants, where they lay their eggs. The larvae then feed on the roots of the plant, which can stunt growth and even kill young plants. In this article, we’ll show you how to get rid of fungus gnats in your cannabis grow operation.


One of the most important ways to prevent and get rid of fungus gnats is to keep a clean grow space. Fungus gnats are attracted to decaying organic matter, so it’s important to remove any dead leaves or stems from your grow space. You should also avoid letting any extra water accumulate on the surface of your grow media or pots. If you see any fungus gnats or their larva in your grow space, be sure to remove them right away.

You can also take measures to prevent fungus gnats from getting into your grow space in the first place. Be sure to inspect any new plants or grow media before bringing them into your space. Fungus gnats can lay their eggs in damp soil, so it’s important to only use sterile, dry grow media. If you start seeing fungus gnats in your grow space, you may need to change your clothes before going into other areas of your home to prevent accidentally spreading them.

Remove all affected plants

If possible, the best solution is to remove all affected plants and start fresh. This will help to ensure that the fungus gnats do not continue to lay eggs in the soil and will also help to prevent any further spread of the infestation. If you cannot remove all of the affected plants, then you will need to take other steps to get rid of the fungus gnats.

Clean all surfaces and equipment

Including countertops, floors, shelves, and grow room tables. Use a safe cleaner such as neem oil to green clean all surfaces in your grow room. Don’t forget to clean your equipment as well. Fungus gnats love to lay their eggs in the tight spaces of equipment like humidifiers and dehumidifiers.

Physical Removal

The first step in getting rid of fungus gnats is to physically remove them from your grow room. This can be done by doing a quick inspection of your plants and removing any larvae or eggs you see. You can also use a small vacuum to remove any adults that are flying around.

Another physical removal method is to use yellow sticky traps. These traps are coated with a sticky substance that will trap and kill any fungus gnats that land on it. You can buy pre-made traps or make your own using yellow construction paper and some adhesive.

Yellow Sticky Traps

One of the most effective ways to get rid of fungus gnats is by using yellow sticky traps. These traps are coated with a special glue that’s designed to trap small insects. You can find them at your local hardware or gardening store, or you can order them online.

To use yellow sticky traps, simply place them around the affected area. Make sure to put them near sources of light, as this will attract more gnats. You should also put them near any plants that have been affected by fungus gnats. Check the traps regularly and dispose of them when they’re full.

Diatomaceous Earth

If you have an infestation of fungus gnats, you can get rid of them by using diatomaceous earth. This is a natural product made from the fossilized shells of algae. It works by puncturing the exoskeleton of the insects, causing them to dehydrate and die. You can find diatomaceous earth at most garden stores or online retailers.

Biological Control

Biological control is using other living organisms to fight your pest problem. For example, you can buy predatory mites that eat fungus gnats or nematodes that feast on the larvae.

Bacillus thuringiensis israelensis, or Bti for short, is a naturally occurring bacterium that’s deadly to dipteran larvae—that’s bugs with two wings, like fungus gnats. Bti comes in dispensaries as powders or pellets that can be mixed with water and sprayed on your plants.

Wetting agents can help Bti work more effectively. You can make your own wetting agent by adding a drop of dish soap to a quart (1 L) of water, or you can buy a product like Saf-T-Side at a grow store. Follow the package directions for how much wetting agent to add per gallon (3.8 L) of water.

Bti Mosquito Dunks

Bti Mosquito Dunks are discs impregnated with a biological larvicide called Bacillus thuringiensis israelensis (Bti). Bti is an insecticide that specifically targets the larvae of gnats, mosquitos, and blackflies. When the larvae ingest Bti, they stop feeding and die within a few days. Because Bti only affects insect larvae, it is harmless to people, pets, and plants.

Bti mosquito dunks can be found in most gardening stores or online. They are easy to use and very effective at getting rid of fungus gnats. To use them, simply place one or two dunks in a container of water and set it near your plants. The larvae will be attracted to the water and will ingest the Bti as they feed.

beneficial nematodes

To get rid of fungus gnats, you can release beneficial nematodes into the soil. Beneficial nematodes are beneficial because they attack and kill pests, but they are harmless to plants, humans, and pets. The most common type of nematode used to get rid of fungus gnats is Steinernema feltiae.

To use nematodes to get rid of fungus gnats, mix the designated amount with water according to the package instructions. Then, using a watering can or similar container, evenly water your plants until the soil is moistened. Make sure to drench the roots so that the nematodes can reach the larvae.

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