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How to recognize fungus gnats

Fungus gnats, or soil flies, belong to a separate family (Sciaridae) inside the mosquito group. Fungus gnats are very common and sometimes become pests in young plants or mushroom growings. Adult fungus gnats usually stand out as ‘dancing’ black flies hovering over the potting soil. Contaminations usually occur through fresh potting soil, which houses larvae or eggs. Fungus gnat larvae eat plant roots. 

The different fungus gnat species are difficult to distinguish. Adult insects are 1-5 mm long, black-gray mosquitos with long legs. Fungus gnats have translucent wings with a characteristic U pattern. The larvae reach 5-12 mm in size and have a remarkable black head and no legs. Their body is white translucent. Pupae are 2-5 mm long and start white but turn yellow or brown.  

Sciarid fly fungus gnat biological control
Fungus gnat side view
Biological control Sciarid fly fungus gnat
Fungus gnat from above

Fungus gnat damage

Larvae of fungus gnats consume rotting plant material and roots of young plants. They prefer humid conditions and can cause large damage in plant nurseries. In addition, larvae can spread mites, nematodes, viruses and fungal spores which take advantage of the feeding damage to enter the plant. The death of (young) plants is usually very local, because larvae are not very mobile. 

Sciarid fly fungus gnat male and female
Male and female fungus gnat

Fungus gnat life cycle

  • life cycle 3-4 weeks, mostly underground
  • egg: 2-4 days
  • larval stage: 2-2.5 weeks
  • pupal stage: 3-4 days
  • adult stage: about 7 days

Fungus gnat host plants

  • no preference for certain plant species
  • moist, humus-rich environment
  • for instance plant nurseries in greenhouses

How to control fungus gnats

There are three products available which can be used to control fungus gnats. The product ENTONEM contains nematodes which enter and consume fungus gnat larvae. ENTONEM can easily be used in many situations to treat the soil before or during growing young plants. ENTOMITE-M and MACRO-MITE are predatory mites that specialize in hunting larvae of many soil-dwelling insects. 

YELLOW STICKY TRAPS can be hung to monitor and partially catch fungus gnats.  

ENTONEM - Steinernema feltiae, Nematodes against fungus gnats
ENTONEM: Nematodes effective against fungus gnats

Our products against fungus gnats


Effective against
- Fungus gnats
- Beetle larvae
- Thrips pupae

HORIVER gele vangplaten


Effective against
- Whiteflies, aphids, thrips and fungus gnats


Effective against
- Fungus gnats
- Several thrips
- European pepper moth


Effective against
- Fungus gnats
- Several thrips
- European pepper moth