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Need to know
- Fungus gnat larvae feed on fungi and organic matter usually in soil.
- Fungus gnat adults do not bite humans.
- Fungus gnats can breed (lay eggs) anywhere that has moisture and decaying vegetable matter.
- In homes, houseplants are the most common breeding area.
- Managment required locating the breeding area and reducing the moisture.
Description of fungus gnats
Fungus gnats are very common, small, non-biting flies that normally go unnoticed. They are completely harmless, except they are an annoyance by their presence. Fungus gnats are frequently quite plentiful outdoors in fungi, damp soil and decayed vegetable matter. Though fungus gnats occasionally wander in from outdoors, a persistent problem with this nuisance in the house indicates an indoor breeding site. The immature stage of the fungus gnat is a small white maggot that lives in very moist areas high in decaying organic matter.
Life-cylce of fungus gnats
Fugus gnats are able to breed indoors given the right conditions. What does breeding indoors mean? It means means that adult fungus gnatsare mating; the females are finding a good place to lay their eggs with moisture and fungi; the eggs are hatching into larvae are feeding on tiny fungi and decaying organic matter and they grow. Once larvae are full grown they transform into pupa. The pupal stage is where the larvae transforms into the adult. Adult fungus gnats have wings and fly around the house, so this is usually what we human inhabitants of the house notice.
Damage caused by fungus gnats
Fungus gnats in homes do not cause damage. The adults do not bite and are just a nuisance. Larvae feeding on in the soil of houseplants do not harm the plant unless they are present in very large numbers. In high numbers they can feed on the roots of seedlings and young plants and stunt their growth.
Management of fungus gnats
The key to management is to find what the larvae are eating. It is no use trying to kill adult insects unless you can kill all females before they lay eggs. So, although the adults are irritating and what you actually see, you have to do some detective work to find the breeding area. Things like sticky cards can alert you to the presence of fungus gnats, but only kill adults which will not solve the problem.
The breeding area must be constantly moist and have decaying organic matter. This habitat may occur indoors with houseplants or in slow-running drains, moisture-accumulating cracks and crevices, refrigerator drain pans, and other places where fungi and slime accumulate.
Houseplants are by far the most common source of fungus gnats. Reduce watering and allow the soil to dry between waterings will reduce fungus gnat problems. Repotting with fresh soil can also help eliminate fungus gnat issues. If you have seedlings in a tray or drainage trays beneath plants this can be another location where fungus gnat larvae can survive.
Insecticides are not effective at managing fungus gnat infestations in household situations. This includes sprays, granular insecticides that are watered in or dissolved and poured over the soil.
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