Easy Methods to Get Rid of Fungus Gnats on Houseplants

Fungus gnats are small dark short-lived insects about 1/8  inch long, adults move rapidly over plants and usually congregate under benches or dark corners. these fruit-flying pests primarily affect indoor plants. The larvae of the fungus gnat feed on algae, plant roots, fungi, and plant stems. The adults do not bite or feed, fungus gnats are attracted to moisture and matter in compost, they typically infest soil, potting mix, and other sources of organic decomposition.

How do Fungus Gnats get Indoors?

The three main ways fungus gnats get indoors our either flying in through an open window with no screen or through an open door, a plant, or soil that is brought indoors that has the eggs or the larvae of fungus gnats. These tiny insects also make their home in the soil in greenhouses. Although fungus gnats are short-lived they can reproduce very quickly which can become a challenge

Signs that You may have a Fungus Gnat Issue

The most obvious sign that your indoor plant has a fungus gnat issue is by physically seeing them because these gnats are weak flyers can be seen either hovering around houseplants or running on the soil surface. Once the larvae hatch they begin to feed on the plant’s root hair where the damage is done.  Other signs of a fungus gnat infestation are the houseplant’s loss of vigor, sudden wilting, yellowing of the leaves, and poor growth.

How to Prevent Fungus Gnats Outdoors

To discourage fungus gnats from outdoor potted plants and soil that may be brought inside or from your outdoor garden and landscape area here is what to do.

• Improve Drainage: One of your first lines of defense is to discourage fungus gnats by improving soil drainage, ensure that your outdoor potted plants have good potting soil that drains well, Do not overwater plants, and allow the top few inches of soil to dry before another water application.
• Cover Garbage: Ensure that trash cans are always clean and covered.
• Eliminate Excess Water: Don’t allow standing water in your garden area, if your soil is poorly drained then add compost or other soil amendments and aerate the soil also.
• Remove Food Sources: Clean up grass clippings, fallen leaves, and other garden debris, where larvae feed. 
• Fix Leaky Pipes: Remember the adult fungus gnat looks for moist conditions to lay their eggs, a broken pipe or irrigation line that’s leaking constitenly will keep the soil moist and will attract the adult so make sure to repair water pipes.
• Turning Compost and Mulch: Routinely turn mulch and compost so that areas that are soggy will dry.
• Add a Top Layer of Gravel or Sand: Because the female lays her eggs in the top few inches of soil adding a layer of decorative stones sand or gravel to the soil surface will help to keep the soil dry. This acts as a barrier and will discourage the female from laying eggs.
• Using a Cover: Soils and compost that are not in use should be covered with landscape fabric to protect from moisture during days when it rains.
• Exterior Lighting: Bright outdoor lights at night will attract insects, use bulbs with low-voltage bug lights that are less attractive to flying insects.

How to Control Fungus Gnats Outdoors

If you discover that you have an infestation of fungus gnats outdoors here is how to bring control.

• Sticky Traps: Sticky traps will capture the adult fungus gant while funnel traps draw them in to drown.
• BTi and nematodes: This approach is effective in controlling the fungus gnat population, apply Bacillus thuringiensis israelensis (BTi) or beneficial nematodes to damp areas. This will kill the larvae and provide ongoing protection.
• Insecticides: Insecticides applied to the soil will eliminate the fungus gnat larvae. Before using insecticides read and follow the manufacturer’s directions for the best results.
• Foggers: Fogging will kill the adults but the effects are not long-lasting.
• Natural Predators: Fungus gnats have natural predators for example Parasitic wasps, mites and other predator insects once introduced into your garden will feed on the (fungus gnat) adult.

Natural Repellents to Control Fungus Gnats Outdoors

• Torches and Citronella candles: The scent that emanates from torches and candles is offensive to gnats and will keep them at bay.
• Outdoor Fans: Outdoor floor and ceiling fans circulate air making it difficult for gants to hang around.
• Essential oils: Lemongrass, eucalyptus, pine, etc… add them to carrier oils for diffusers, these homemade repellents are effective for fungus gnat control.
• Plants: Many plant species will keep fungus gnats at bay for example crushing the leaves of mint, marigold, basil lavender, etc… will activate the oil that will repel gnats.

How to Control Fungus Gnats Indoors

If you have a fungus gnat infestation indoors here is how to bring control.

•  Overwatering: Avoid overwatering indoor plants.
• Hydrogen Peroxide: Make a solution by mixing 1 part hydrogen peroxide and 4 parts water, then pour the mixture into the pot, and completely saturate the soil. This solution will kill the eggs and the larvae.
• Sticky Traps: The use of sticky traps will capture the adult fungus gnat.
• Proper Drainage: Ensure that indoor plants have proper drainage, allowing the soil to dry between watering will discourage the presence of fungus gnats.
• Apple Cider Vinegar: Use a small cup with 1 inch of apple cider vinegar and cover it tightly with plastic wrap poke small holes around the top of the wrap. The gnats will be able to enter the holes, but will not be able to exit.

Conclusion

Fungus gnats are common on indoor plants while the adults will not harm indoor plants the larvae are the culprit that does the damage, the good news is these pests can be controlled by following this guide. The presence of the adult may raise concern but these indoor pests are short-lived and putting these methods to work will work for you as their population is reduced and total control is brought about. If you have issues with these pests then contact us and let us help you put a plan in place that will bring total elimination.