Effective Methods for Eliminating Fungus Gnats from Your Houseplants

Are you struggling with fungus gnats infesting your houseplants? These annoying pests can be a real nuisance, but there are effective ways to get rid of them.

In this article, we will explore various methods to eliminate fungus gnats from your plants. Whether you prefer organic solutions or other methods, we have got you covered.

By understanding the life cycle of fungus gnats and the conditions that promote their growth, you can take the necessary steps to control and eliminate them.

Understanding the Fungus Gnat Life Cycle

Before diving into the methods of eradication, it is crucial to comprehend the life cycle of fungus gnats. According to Cornell University, this life cycle consists of four stages: adult, egg, larva, and pupa.

The adult female fungus gnats lay up to 200 eggs on the surface of the potting mix, which take around 3-6 days to hatch.

The larvae then feed on the potting mix for about 2 weeks before pupating for 3-7 days. Finally, the adult fungus gnats emerge and restart the cycle.

It’s important to note that the temperature at which your houseplants are growing significantly affects the length of the life cycle. Lower temperatures can prolong the cycle.

Optimal temperatures for fungus gnat development range from 70-75°F (21-24°C). Understanding their life cycle allows you to target all stages of the gnats effectively.

Step 1: Control Your Cultural Conditions

Creating the right cultural conditions is the first step in eliminating fungus gnats from your plants. Factors such as temperature, media type, and potting mix moisture can influence the prevalence of these pests.


Fungus gnats thrive in temperatures ranging from 70-75°F (21-24°C). While you may not have complete control over the temperature, it’s worth noting that adjusting it can impact the development of fungus gnats.

Media Type

Fungus gnats are attracted to potting mixes that contain organic materials like compost, blood meal, and kelp.

These materials provide a favorable environment for the growth of fungi and other microbes, which serve as a food source for the larvae.

While organic mixes can be beneficial for plant growth, they may also attract fungus gnats.

Potting Mix Moisture

Fungus gnats prefer moist potting mix, particularly in the top inch or so. To manage the proliferation of fungus gnat larvae, allow the top portion of the potting mix to dry out before watering again.

By creating drier conditions, you make it less hospitable for the eggs and larvae, reducing the number of gnats that reach adulthood.

Step 2: Capture Adult Fungus Gnats With Traps

While controlling the moisture of your potting mix, it is essential to trap the adult fungus gnats. Sticky yellow traps are highly effective in capturing these weak-flying pests.

The yellow color attracts them, and once they land on the traps, they become stuck and unable to fly away. This method prevents the adults from laying eggs in your potting mix and continuing the life cycle.

You can find a variety of sticky yellow traps available, including ones that can be hung or inserted into the potting mix.

Place the traps strategically near your plants to maximize capture. However, it’s important to note that trapping alone will not completely eliminate the fungus gnat problem.

Step 3: Treat Potting Mix to Kill the Larvae

To ensure the complete eradication of fungus gnats, it is necessary to treat the potting mix and eliminate the larvae. Two effective methods for killing the larvae are biological control and systemic insecticides.

Biological Control

If you prefer a more natural approach, Mosquito Bits can be an excellent option. Mosquito Bits are corn cob granules coated with BTI bacteria (Bacillus thuringiensis subspecies israelensis).

When the larvae consume these granules, the BTI bacteria kill them. Mosquito Bits are non-toxic to humans and pets when used properly.

To treat fungus gnats with Mosquito Bits, sprinkle them on the surface of the potting mix, ensuring a complete layer covering. Water your plants as usual, releasing the BTI into the mix.

The larvae will feed on it and eventually die. Repeat this process weekly for at least three weeks, or even a month for better results.

Systemic Control

Another option is using a systemic insecticide, such as Bonide Systemic Houseplant Insecticide. These insecticides are not available everywhere and may not be allowed in certain countries. However, they are highly effective in killing fungus gnat larvae.

Apply the systemic insecticide to the potting mix as directed on the label and water it in. The insecticide will be absorbed by the plant, protecting it from not only fungus gnats but also other pests.

The protection can last up to eight weeks. Combining systemic insecticides with other treatments can provide even better results.

Fungus Gnat Treatment Summary

To effectively control and eliminate fungus gnats from your houseplants, follow these three steps simultaneously:

  1. Control your cultural conditions by adjusting temperature, being mindful of the media type, and allowing the top inch of the potting mix to dry out before watering again.
  2. Capture adult fungus gnats with sticky traps to prevent them from laying eggs and continuing the life cycle.
  3. Treat the potting mix using biological control methods like Mosquito Bits or systemic insecticides like Bonide Systemic Houseplant Insecticide to kill the larvae.

By diligently following these steps for three to four weeks, you can successfully minimize and eliminate fungus gnat infestations. Remember to be persistent in your pest control efforts and monitor your plants regularly.

If you’ve experienced fungus gnat infestations before, share your story in the comments below. For more information on treating other pests like scale insects or spider mites, check out our related articles:

Don’t forget to share this article on social media to help others combat fungus gnats.

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