If you are exploring to find the best pesticide for gnats in houseplants, here are 10 of them. I provide you with a list of the chemical, homemade, and natural insecticides that can work well as a gnat killer for indoor plants.
I also will show you how to use them and tell you pro tips that will enhance their efficiency. After reading this article you can choose your best pesticide for gnats in houseplants.
Fungus gnats are common tiny bugs on houseplants, and their larvae live in wet rich soil and feed on roots. If you don’t get rid of them immediately, they will kill your lovely indoor plant. so, don’t waste time, and let’s start our journey in the world of insecticides that can kill them.
A: Natural Pesticides for Gnats in Houseplants
Do you know what is a Natural pesticide? When an insecticide is derived from natural substances, we call it a natural pesticide. The natural substances can be plant extracts, minerals, microbes, or other organic materials.
They interfere with pest biology or behavior such as:
- Disrupting the insect’s life cycle.
- Deterring feeding.
- Physically damage the pest.
Below, you can see a list of the natural pesticides for gnats in houseplants. I will tell you how to use them in the next parts of this article, here only find their names.
Neem oil is a natural pesticide derived from the neem tree.
- Bacillus thuringiensis (Bt):
Bt is a natural pesticide consisting of a bacterium that produces toxins harmful to certain insects.
- Beneficial Nematodes:
Beneficial nematodes are natural predators of soil-dwelling pests, including fungus gnat larvae.
- Azadirachtin:
Azadirachtin is a natural insect growth regulator derived from neem seeds.
- Spinosad:
Spinosad is a natural pesticide derived from soil bacteria.
- Diatomaceous Earth:
Diatomaceous earth is a natural and physical pesticide made from the fossilized remains of diatoms.
- Insecticidal Soap:
Insecticidal soap is a natural pesticide made from potassium salts of fatty acids.
B: Homemade Spray for Fungus Gnats in indoor plants
In this article, I will provide you with two of the best DIY (Do It Yourself) insecticide sprays that can kill the fungus gnats too. below I only mention their names, however, I will discuss them in detail in the final part of this article.
- Neem Oil:
Neem oil can be mixed with water and a small amount of mild soap for use as a homemade pesticide spray.
- Insecticidal Soap:
Homemade insecticidal soaps can be created using ingredients like liquid dish soap and water. Care should be taken to avoid using soaps that contain harsh chemicals.
C: Chemical Fungus Gnat Insecticides in House plants
We call an insecticide a Chemical pesticide when it is a synthetic or man-made substance. Hence, they are manufactured in laboratories and target specific biochemical pathways or systems within the pests for example their nervous system, growth, or reproduction. In the following, you can find a list of the chemical pesticides for gnats in houseplants. I will discuss them in detail in the next parts.
- Pyrethrin:
Pyrethrin is a chemical pesticide derived from chrysanthemum flowers that usually is combined with piperonyl butoxide or other synthetic adjuvants.
- Imidacloprid:
Imidacloprid is a synthetic chemical pesticide that belongs to the neonicotinoid class.
- Permethrin:
Permethrin is a synthetic chemical pesticide and belongs to the pyrethroid class.
What is the Best Pesticide for Gnats in Houseplants?
If you ask me, as a general rule the best insecticide for use in houseplants is a homemade natural pesticide such as neem oil. But sometimes we have to use other options. Various factors can have an impact on our decision, for example, the severity of infestation, how much our indoor plant is expensive or rare, and our budget.
Sometimes you should buy a natural pesticide such as beneficial nematodes that work well in controlling fungus gnats. In some situations, the only way is by applying a powerful chemical insecticide such as Pyrethrin or even Imidacloprid.
In the following, you can find an instruction for using the above Pesticides for Gnats in Houseplants. keep reading.
How to Use Fungus Gnat Insecticides in House Plants?
In previous parts, you find various types of gnat killers for indoor plants. Now come on to tell you how to use them and pro tips for improving their efficiency. After reading this part you can decide which one is the best for your house conditions.
1- Neem Oil:
Neem oil is a homemade spray for fungus gnats that disrupts their life cycle and acts as a repellent.
- Action: Acts as a growth regulator and repellent.
- Effect: Effective against both larvae and adults.
How To Use Neem Oil to Get Rid of Fungus Gnats?
- Mix neem oil with water according to the product instructions.
- Apply the solution to the soil, thoroughly wetting the top layer.
- You can also pure it in a bottle and spray it on foliage for adults.
- Treat affected plants every 7-14 days especially if fungus gnats persist or reappear.
Pro Tip: Apply neem oil as a preventive measure or at the first sign of fungus gnats. Ensure thorough coverage of both the soil and plant foliage.
2- Pyrethrin:
Pyrethrin is derived from Chrysanthemum flowers and is effective against a variety of insects, including fungus gnats.
Action: Contact insecticide affecting the nervous system.
Effect: Effective against adult fungus gnats.
How To Use Pyrethrin to Get Rid of Fungus Gnats?
- Mix pyrethrin with water as directed on the product label.
- Spray the solution directly onto the adult fungus gnats.
- Repeat the application as needed, following label instructions.
Pro Tip: Use pyrethrin during the early stages of fungus gnat infestation for maximum effectiveness. Apply in the evening when adult gnats are most active.
3– Bacillus thuringiensis (Bt):
Bt is a bacterium that produces toxins harmful to certain insects, including fungus gnat larvae. It’s considered safe for humans and pets.
Action: Produces toxins harmful to larvae.
Effect: Primarily affects fungus gnat larvae.
How To Use Bacillus thuringiensis (Bt) to Get Rid of Fungus Gnats?
- Mix Bt with water following the product instructions.
- Apply the solution to the soil where fungus gnat larvae are present.
- Repeat as necessary (every 7-14 days), adhering to label guidelines. Monitor the infestation and adjust the frequency accordingly.
Pro Tip: Treat the soil with Bt when larvae are present. Reapply after heavy rainfall, as it may wash away the bacteria.
4- Beneficial Nematodes:
Certain species of beneficial nematodes, like Steinernema feltiae, can be applied to the soil to control fungus gnat larvae.
Action: Parasitize and kill larvae in the soil.
Effect: Primarily affects fungus gnat larvae.
How To Use Beneficial Nematodes to Get Rid of Fungus Gnats?
- Mix beneficial nematodes with water as instructed.
- Water the soil with the nematode solution, targeting areas with larvae.
- Apply during the evening or on cloudy days.
- Repeat applications every 2-4 weeks as recommended on the product label. Repeat applications may be necessary for ongoing control.
Pro Tip: Keep the soil consistently moist for a few days after applying beneficial nematodes to enhance their effectiveness. Apply during the evening or on cloudy days to protect them from sunlight. If you need to know more about the Nematodes for fungus gnats in houseplants, read my previous article.
5- Azadirachtin:
Azadirachtin is an insect growth regulator derived from neem seeds. It disrupts the growth and development of fungus gnats.
Action: Insect growth regulator.
Effect: Effective against both larvae and adults.
How To Use Azadirachtin to Get Rid of Fungus Gnats?
- Mix azadirachtin according to the product label.
- Apply the solution to the soil or pure it into a bottle and spray on foliage.
- Treat affected plants every 7-14 days. Regular applications may be necessary to disrupt the life cycle of fungus gnats.
Pro Tip: Combine azadirachtin treatment with other control methods for a comprehensive approach. Repeat applications regularly to disrupt the life cycle.
6- Spinosad:
Spinosad is an organic pesticide derived from bacteria. It’s effective against fungus gnats and is considered safe for use on ornamental plants.
Action: Disrupts the nervous system.
Effect: Effective against both larvae and adults.
How To Use Spinosad to Get Rid of Fungus Gnats?
- Dilute spinosad with water according to the instructions.
- Spray the solution on affected plants, ensuring good coverage.
- Repeat the application if necessary, following label guidelines. Monitor the infestation level to determine the need for additional treatments.
Pro Tip: Rotate spinosad with other pesticides to prevent the development of resistance. Apply in the early morning or late evening to minimize the impact on beneficial insects.
7- Diatomaceous Earth:
While not a traditional pesticide, diatomaceous earth can be used as a physical barrier. It is a powder that damages the exoskeleton of insects, including fungus gnats.
Action: Physical barrier, damages the exoskeleton.
Effect: Primarily affects adult fungus gnats.
How To Use Diatomaceous Earth to Get Rid of Fungus Gnats?
- Apply a thin layer of diatomaceous earth on the soil surface.
- Reapply after watering or rainfall. Depending on the severity of the infestation, repeat every 7-14 days.
- Use caution to avoid inhaling the dust.
Pro Tip: Reapply diatomaceous earth after watering or rain, as moisture reduces its effectiveness. Use food-grade diatomaceous earth for safety. You can find more tips about using it in houseplants in my article about tiny silver bugs in houseplants.
8- Insecticidal Soap:
Insecticidal soaps, based on potassium salts of fatty acids, can be effective against fungus gnats. They disrupt the cell membranes of insects.
Action: Disrupts cell membranes.
Effect: Primarily affects adult fungus gnats.
How To Use Insecticidal Soap to Get Rid of Fungus Gnats?
- Mix insecticidal soap with water following the recommended ratio:
2.5 tablespoons of liquid Horticulture soap + 2.5 tablespoons of vegetable oil + one gallon of warm water.
- Spray the solution directly on adult fungus gnats.
- Apply every 7-10 days or as needed. Regular applications may be necessary, especially if fungus gnat populations persist.
Pro Tip: Ensure thorough coverage, especially on the undersides of leaves where adult fungus gnats may hide. Use in conjunction with other control methods for a more comprehensive approach.
9- Imidacloprid:
Imidacloprid is a systemic insecticide that can be applied to the soil. It is absorbed by the plant and can control fungus gnat larvae that feed on the plant sap.
Action: Systemic insecticide affecting the nervous system.
Effect: Primarily affects fungus gnat larvae through the plant’s vascular system.
How To Use Imidacloprid to Get Rid of Fungus Gnats?
- Apply imidacloprid as a soil drench according to the label instructions.
- Water the treated plants as directed.
- Repeat as necessary, adhering to label guidelines. Typically, every 4-8 weeks. Monitor plant health and adjust the frequency as needed.
Pro Tip: Apply imidacloprid as a soil drench when fungus gnats are in the larval stage. Monitor treated plants for any signs of stress or adverse reactions.
10- Permethrin:
Permethrin is a synthetic pyrethroid that is effective against a variety of insects, including fungus gnats.
Action: Synthetic pyrethroid affecting the nervous system.
Effect: Effective against adult fungus gnats.
How To Use Permethrin to Get Rid of Fungus Gnats?
- Mix permethrin with water according to the product label.
- Spray the solution on affected plants, targeting adult fungus gnats.
- Follow the recommended frequency of application. Adjust the frequency based on the severity of the infestation.
Pro Tip: Apply permethrin in the evening to minimize exposure to pollinators. Use caution with edible plants, and follow the recommended pre-harvest interval.
The General Tips for Using Insecticides in Houseplants
- Always follow the instructions on the pesticide label carefully
- Get help from non-chemical methods for controlling fungus gnats too, such as allowing the topsoil to dry out between watering. I discussed these ways in my previous article about small black gnats in houseplants.
- various factors have impacts on the effectiveness of every pesticide, for example, the specific product, its concentration, and the stage of the fungus gnat life cycle.
- Before the widespread application of every pesticide, perform a spot test on a small part of the plant.
- Study the integrated pest management (IPM) strategies to enhance the effectiveness of your pest control efforts.
- After applying a pesticide, monitor its effectiveness and adjust your approach.
Conclusion
I told you about various types of pesticides for gnats in houseplants including, natural, chemical, and homemade sprays. I showed you how to use them and pro tips to improve your efforts for controlling fungus gnats.
Do you think which one is the best insecticide for fungus gnat killing? Why? please share your ideas and experiences with our readers below this page.
Elahe Rabiei
Hi, I’m Elaheh. My Academic major is plant protection, and houseplants are my expertise. As a houseplant lover, my house is full of indoor plants and it is my passion to take care of them. Hence, I’m here to share my knowledge and experience about growing healthy houseplants. I am also a plant protection advisor, so feel free to ask me any questions you may have.