Home Remedies for Gnats in Plants

Houseplants may be affected by a variety of insects that come indoors. Fungus gnats are common pests of houseplants and occur in areas where algae, fungi, and decaying vegetation are abundant. Although fungus gnats are not harmful to humans, they can become a nuisance when present in large numbers. Natural remedies can help reduce and eliminate fungus gnat infestations in young plants grown indoors.

Identification Of A Fungus Gnat Infestation

Adult fungus gnats are black small flies that resemble tiny mosquitoes and measure 1/16 to 1/8 inch in length. These type of gnats have transparent wings and long legs, with some species having Y-shaped wing veins. Adult fungus gnats are not strong fliers and usually hover near infested indoor plants.

The larval stage of fungus gnats live in the soil of infested houseplants, where they feed on decaying plant tissue and fungi on the soil surface. Larvae have shiny, black head capsules and a long, white, or clear body. These pests feed on the plant roots hairs of infested plants, algae, fungi, and mold. Adult fungus gnats are often a nuisance for homeowners because they swarm when infested houseplants are moved or bumped. These gnats may be seen hovering directly over infested plants or in sunny windows near infested plants.

Natural Methods to Rid Gnats in Plants

Fungus gnats thrive in soils that have excess moisture. Homeowners who have fungus gnat infestations should reduce the amount of water their houseplant receives. The larvae of fungus gnats live in the top 1 to 2 inches of soil. 

Allowing the potting soil to dry completely between watering times will kill many of the larvae before they pupate into adult fungus gnats. Houseplants typically require less water during the winter months, so adjust your watering schedule according. Failure to reduce the amount of water provided to houseplants during the winter can result in fungus gnat infestations and fungal diseases.

Traps The Effective Way For Your Fungus Gnat Problem

Swarming adult fungus gnats are bothersome to homeowners. Since adult gnats are attracted to light, placing yellow sticky traps on the windowsill near infested plants will help capture fungus gnats and reduce infestations. Adult gnats are drawn to the yellow-colored cards and become trapped, which can help reduce egg-laying.

Beneficial Nematodes Are A Good Idea

Nematodes are a form of biological control that can eliminate fungus gnat larvae, preventing them from pupating into adult gnats. Steinernema feltiae are insect-reducing nematodes that are applied as a soil drench. Apply right after planting, and repeat every two or three weeks to prevent fungus gnat infestations. Nematodes are most effective in keeping fungus gnat populations low but are not an effective means of reducing severe infestations.

How To Kill Gnats’ Eggs In Your Houseplants

Fungus gnats lay eggs within the first two to three inches of plant soil. Generally, gardeners will notice tiny insects of these houseplant pests that resemble mosquitoes flying around their houseplants, indicating fungus gnats. When the eggs hatch, larvae eat away at the houseplant’s root system, which causes a host of health problems.

Houseplants infested with fungus gnats display symptoms such as leaf yellowing, wilting, stunted growth, and defoliation. Left untreated, houseplants may die. Treating fungus gnats using both cultural and chemical methods kills eggs.

Tilt the houseplant on its side and twist off the container. Dump the dirt from the container into a trash bag. Secure the bag and throw it away. Pour the new potting medium into the container.

Shake the potted plants gently to remove some of the old potting medium containing gnat population eggs from the root system. Create a hole inside the fresh potting medium that is twice the size of the root ball of the houseplant and at the same depth it was planted. Place the plant inside the potting medium and pack soil around the base.

Apply a soil drench to the container. Use a soil drench that contains Bacillus thuringiensissubsp. israelensis. The insecticide kills fungus gnat larvae by infecting them with a bacteria that causes them to starve. Re-apply as necessary.

Spray the new houseplant with a pesticide to kill adult fungus gnats. The pesticide should contain an active ingredient such as bifenthrin, cyfluthrin, permethrin, or lambdacyhalothrin. Apply the pesticide to the foliage of the houseplants.

Place yellow sticky cards around the houseplant. Sticky cards draw adult fungus gnats and trap them, reducing infestations and giving gardeners a clue when a new infestation has occurred.

Tips & Warnings Of An Effective Treatment

Reduce the amount of water for houseplants because excessive watering encourages fungal gnat infestations. Water houseplants when the surface of the soil has dried out.

Place pesticide-treated houseplants in an area away from children and pets.

Homemade Remedy For Fungus & Gnats

Fungus gnats are small black insects that attack growing seedlings and if the infestation is severe can cause damage to the seedling. The experienced gardener will start their plants from seeds, which is a very rewarding experience, and watch them sprout and grow as opposed to buying the developed plant and sticking it in the ground.

Home Remedy And Natural Methods

The fungus gnat will search out moist soil to lay eggs and when the eggs hatch the larvae will nibble on the roots of the plants. Fungus gnats are more annoying than harmful, and plants that are well established may not be affected but new seedlings and smaller plants can be damaged if the infestation of the gnats is large enough. Fungus gnats are drawn to moisture and if the soil appears to be too moist, skip watering until the soil drys out. Gnats will not be drawn to dry soil and will look for another place to lay their eggs.

To trap the adult population of gnats, sit a few dishes of water around your seedlings with vinegar and a few drops of dish soap. The vinegar will attract the gnats and the dish soap will weigh them down, drowning the little pests. 

You can also take a bright yellow piece of paper as the gnats are drawn to this color and smear it with petroleum jelly. Attach the paper to a Popsicle stick and stick it close to your plant or hang it in the area where the gnats are most actively flying around. When they bump into the jelly they will get stuck and die.

You can also sprinkle cinnamon over your seedlings as this is a natural fungicide. Other home remedies you can use to kill larvae on your plants are 1/4 cup of rubbing alcohol mixed with 1 cup of water and 1/2 tsp. of dish soap. Put these ingredients in a spray bottle and spray your plants liberally. You can also dilute 2 tbs. of Cheyenne pepper in 1 cup of water and spray your plants.

After spraying plants, wait several hours, then take a clean sponge or cloth and wipe your leaves to remove dead larvae and gnats. Keep a pan of hot soapy water on hand, rinsing the leaves as you go, and be careful you do not spread the pests to other plants while washing the leaves.