Fungus Gnats

Adult fungus gnats are tiny, measuring no more than 1/8" in length. Fungus gnats have a very short lifespan. The adult female fungus gnat will lay up to 300 eggs in damp soil then in about a week or so, the adult male and female will die.

During their life span, fungus gnats carry plant disease from one host plant to another, creating big problems for home gardeners.


So... What are Fungus Gnats?

Adult fungus gnats are tiny, measuring no more than 1/8" in length. They have medium gray to black bodies with clear or light grayish wings.

Fungus gnat larvae have whitish bodies and reach about 1/4" maximum length. Eggs are somewhat round in shape and are either clear or light in color, making them difficult to see.

Fungus gnats can be annoying to gardeners, homeowners with indoor plants, and greenhouse staff.


Reproduction Patterns of Fungus Gnats

Fungus gnats have a very short lifespan even though they do go through four stages of development. The adult female fungus gnat will lay up to 300 eggs in damp soil then in about a week or so, the adult male and female will die.

After the eggs hatch in about 5 days, the larvae will emerge and feed on the plants and organic matter. At the end of two weeks of feeding, the larva will pupate for 5 days or so before emerging as an adult who is ready to mate and lay eggs.

This continual cycle can result in large numbers of fungus gnats during an infestation.

Fungus Gnat's Habitat

Fungus gnats prefer dark, damp areas found in organic material and soil. They appear to favor African violets, poinsettias and cyclamens as well as bedding and foliage plants.


Symptoms of Fungus Gnat Damage

Adult fungus gnats may be seen flying around lighted areas. Symptoms of infestation of the fungus gnat adult and larvae in plants include poor growth, wilting, yellowed leaves and falling leaves.


Results of a Fungus Gnat Infestation

The most common problem with fungus gnats is that they carry plant diseases from one plant to another. Plant diseases may even be transported from one garden to another through fungus gnats.

The larvae can cause serious injury to a plant's roots, interfering with the plant's growth or causing the death of the plant.


Natural & Organic Controls


Safer® Brand Yard and Garden Insect Killer can help control an infestation of fungus gnats if they are spotted on your plants.

Sticky traps such as Safer® Brand Sticky Stakes are also an excellent method of controlling fungus gnats.


Insecticidal Soap (Potassium Salts of Fatty Acids) & Pyrethrin products such as Safer® Brand Yard and Garden Insect Killer - are the equivalent of a 1-2 knock down punch. Fungus gnats are tough bugs to kill. The soap will penetrate their shell enough to weaken and dehydrate the insect and allow the pyrethrin to absorb in to the insect and do its job.

Pyrethrin is a nerve agent and will paralyze and kill the insect on contact. Keep in mind this soap is not like dish detergent, it's a base from a blend of plant sources and pyrethrin oils and comes from the chrysanthemum flower.

Safer® Brand Sticky Stakes attract and trap fungus gnats in indoor houseplants when placed directly above the plant or directly into the soil at the base of the plant.


Spray Safer® Brand Yard and Garden Insect Killer as a contact killer. Use in accordance with directions on the product label.

Safer® Brand offers a variety of fungus gnat control products to help control and eliminate this garden pest and revive your plants. Please check out our fungus gnat control products for more details about how they work and how, when, and where they should be applied.

If you are concerned about a plant or unsure of how it will react to these solutions, test an inconspicuous area and wait 24 hours before full coverage. As a general rule, much like watering, do not use any liquid insecticides in the peak of the day or when temperatures exceed 90°F.

Place the Safer® Brand Sticky Stakes as soon as you see the first signs of fungus gnats.


Natural Predators


Fungus gnats have a predator that actually is named for the tiny pest. Fungus Gnat Predators (Hypoaspis aculeifer) look particularly for fungus gnats as well as other garden pests.


Fungus Gnat Predators (Hypoaspis aculeifer) pierce the larvae and feed on their contents. Both adult and nymph fungus gnat predators will prey on the fungus gnat. These beneficial predators are usually sold commercially in shaker containers and spread over the soil. They will dig into the soil where they will dwell and females will lay their eggs.

Use caution when introducing predators in conjunction with insecticides. Spray an organic insecticide first. Then introduce the predatory species to kill the rest of the infestation. Otherwise the insecticides may also kill these beneficial insects or arachnids.


If using commercially produced Fungus Gnat Predators, be sure to read and follow all instructions that accompany the product to find out when to disperse the mites on the plants. They should be applied before fungus gnat populations become established or when populations are low.

Safer® Brand leads the alternative lawn and garden products industry, offering many solutions that are compliant with organic gardening standards. Safer® Brand recognizes this growing demand by consumers and offers a wide variety of products for lawns, gardens, landscapes, flowers, houseplants, insects and more!