Getting Rid Of Fungus Gnats
Fungus gnats are tiny insects, about 1/8 inch long, that resemble very small mosquitoes. They are often first notices around new seedlings, on which they like to prey. Since fungus gnats are so tiny, they are capable of entering a greenhouse or home through even the tiniest of openings.
Therefore, even your indoor plants are not safe from these pests. In addition, their eggs are known to hitch a ride in damp bags of soil bought from stores or in the soil of a plant that may have been outside.
Adult fungus gnats do not really cause much direct damage to plants, though they can be a nuisance to you as they fly about. The larva, however, can cause a great deal of damage to seedlings and other young plants because they feed on their tender roots. Although it is not yet know for certain, most experts also believe they feed on the developing callus of plant cuttings. This results in a delay in new root development.
The overall stress fungus gnats place on a plant causes it to become weaker. This makes it easier for disease pathogens to gain entryway to the plant and cause further damage. The first sign of a fungus gnat larva infestation is usually wilting, which is followed by an overall decline in the plant’s health.
The fungus gnat lays its eggs in the cracks on the surface of soil. The larva hatch within six days after being laid, at which time they begin feeding on the roots of the plant. After feeding for approximately two weeks, they pupate within the soil. In less than a week, they come out of the soil in adult form and start the cycle once more.
Most of the fungus gnats born are females, which helps their population grow quickly. In fact, just one female fungus gnat can lay anywhere from 100 to 300 eggs at a time.
To check your soil for fungus gnats, you can place yellow sticky cards in a standing position on the surface of your soil. This will attract the adult gnats and hold them in place, which will give you an idea of how large your fungus gnat population is.
To draw out the larva, you can place a potato slice on the surface of your soil. When they begin feeding on the potato slices, you can collect them and dispose of them properly. Make sure you do not allow the potato slices to dry up, however, as this will only encourage the larva to return to the roots of your plants. This also helps you determine what stage your population is in and when the larva is feeding. If you choose to use pesticides to get rid of your fungus gnats, it is best to do so at this time.
If you decide to build a greenhouse, be sure to thoroughly clean it out before beginning new seedlings. Things such as weeds and soil on the floor of the greenhouse will attract fungus gnats to the area.
If you are having a real problem with fungus gnats, avoid using potting mixes in your garden that have fresh compost additives. The high microbial activity of these mixes tends to attract fungus gnats. It is also best to use a potting mix that has been well drained, as fungus gnats are attracted to soil that remains moist. For this reason, potting mixes that are left outdoors and allowed to remain wet may also contain the larva of fungus gnats. In addition, the larva enjoys eating any organic material found in your soil.
If everything you have done to prevent fungus gnats has not worked, you can try a few different biological methods for getting rid of them.
A bacteria called Bacillus thuringiensis has proven to be effective in getting rid of fungus gnats while their larva is in the feeding stage. It is important to apply this when the larva are eating because they must eat the bacteria in order to be affected. This bacteria is sold under the brand name of Gnatrol, though it is only active for two days and will need to be reapplied accordingly.
A nematode called Steinernema feltiae is also effective when used to soak the soil of the garden. These worms enter the fungus gnat larva and release a bacterium that is lethal to them.
Both Steinernema feliae and Bacillus thuringiensis are living organisms. Therefore, you probably won’t find them available at your local garden center. Rather, you will probably need to order them from a catalogue. During the seed starting season, you might also find them available in some nurseries.
If you cannot find these biological eradicators, you can purchase a general flying insect spray or a spray created specifically for gnats. Be sure to purchase one containing pyrethrins. These sprays will, however, only kill the adult fungus gnats and you will need to apply multiple applications.