Foil nuisance sciarid £ies!
Chemical-free ways to rid pot plants of them
Small sciarid flies, or fungus gnats, are attracted to moist compost and can be a nuisance when they invade your greenhouse or indoor pot plants. Hovering around the compost, the flies breed all year, laying their eggs on the surface. Their white larvae feed predominantly on dead and decaying organic matter but will attack young plant roots, which can seriously damage weak plants or seedlings.
The good news, though, is that they’re very easily controlled. ● Put up sticky traps Hang a yellow sticky fly trap near affected plants and, provided it’s close to the compost, the sciarid flies will be attracted to the yellow traps. Available from garden centres or Marshalls for £3.99 for a pack of five (tel: 0844 557 6700; www.marshallsseeds.co.uk). ● Put gravel on the compost surface
Only use sterilised compost, then cover the top of your pots with gravel, or small pebbles, to prevent flies from laying their eggs in the compost. ● Let compost dry between waterings The microscopic fungi and algae, on which the larvae feed, thrive in damp compost, so let pots dry out between waterings. ● Introduce biological control Grow sticky carnivorous sundew (drosera) plants nearby to trap the fungus gnats or water the nematode Steinernema feltiae on to indoor plants to control eggs and larvae. Sciarid Fly Nematodes cost £10.99 (treats 15 sq m compost) from Nematodes Direct (tel: 0808 901 2055; www.nematodesdirect.co.uk).