PestmediumMar–Oct

Fungus gnats

Sciaridae

This description was machine-translated.

How to spot it

Fungus gnats are small, black flies from the family Sciaridae whose larvae live in moist potting compost, where they feed on root hairs and young shoots. The adults are noticed above all when watering, when they rise from the surface of the soil in swarms. The actual damage is done by the whitish, black headed larvae: they weaken the roots, which makes seedlings and sensitive house plants such as begonia or fuchsia wilt or keel over suddenly. Seed trays and pots that are kept permanently moist are especially at risk.

Prevention

Let the top few centimetres of the soil dry out between waterings, which takes away the larvae's basis of life. Yellow sticky traps near the pots catch the flying gnats and show an infestation early. A layer of sand or a fine quartz gravel covering on the soil surface makes egg laying harder for the gnats. Use beneficials such as predatory mites or nematodes against the larvae and choose a low peat, well aerated growing medium, which prevents waterlogging and with it a new infestation.