Home / Pests
Fungus gnats and sciarid flies
Family Sciaridae
Fungus gnats are the tiny black flies that hover around houseplants and seed trays. The flies are a nuisance, but their larvae feed on roots and seedlings in the compost and can spread root disease.
- Found inHouseplants, seed trays and glasshouses
- Best time to treatAny time of year indoors
The larva: see-through with a black head 
The adult: a tiny black fly 
The damage: seedlings that collapse
Signs
How to tell you have fungus gnats and sciarid flies
- Small black flies around pots, seed trays and windows
- Seedlings and cuttings that collapse or root poorly
- Plants in damp compost that stop growing
- Thin, see-through larvae with a black head in the top layer of compost
How to check
Put a slice of raw potato on the compost surface for a few days, then turn it over. Fungus gnat larvae gather underneath it.
Timing
When to treat
Grubs feedingBest time to treat
Treat as soon as you see the flies, at any time of year, as long as the compost is between 8°C and 28°C. Let the surface dry out a little between waterings to stop new flies laying eggs.
The treatment
Nematodes for fungus gnats and sciarid flies
-
nemaplus - Fungus Gnat Nematodes
Steinernema feltiae, for fungus gnats and thrips larvae in houseplants, propagation and glasshouses.
From €14.95
Delivered across Ireland by tracked courier, packed to stay fresh. Order by 10:00 on Wednesday for delivery the following week. Days can change around bank holidays in Ireland and Germany.
Why biological control
Natural pest control, without the drawbacks
Chemical pesticides can leave residues behind in the garden. Beneficial nematodes work differently. They hunt the pest in the soil, then die back naturally once it is gone.
No chemical residues
Nematodes are living organisms, not chemicals, so there are no chemical residues on lawns, fruit or vegetables.
Safe around people and pets
Safe to use around children, pets and wildlife. You can use the garden as normal after watering them in.
A targeted effect
Each nematode seeks out its target pest in the soil and leaves everything else alone.
Found naturally in soil
Beneficial nematodes already live in healthy soil. We simply add more where the pests are.
Works differently from sprays
Nematodes hunt pests and enter their bodies, a completely different way of working from chemical sprays.
How to apply
Six simple steps
-
Store cold
Fridge at 2–8°C. Never freeze.
-
Pick your time
Evening or a dull day, soil 12°C+.
-
Mix
Stir the pack into a bucket of water.
-
Apply
Water it on. Keep stirring as you go.
-
Water in
Keep soil moist for 2 weeks.
-
See results
Nematodes start working within days of watering in.
Everything you need comes in the pack. Delivered across Ireland, packed to stay fresh.