Fungus Gnat & Sciarid Fly Nematodes Natural Control for Houseplants, Greenhouses & Seedlings
If you're seeing small, dark flies hovering around your houseplants, seedling trays, or greenhouse compost, you almost certainly have fungus gnats, also known as sciarid flies or compost flies. The adult flies are a nuisance, but the real damage is done out of sight: their larvae live in the top few centimetres of compost and feed on the fine root hairs of plants, causing stunted growth, wilting, and seedling collapse. In heavy infestations, larvae can also spread soil-borne diseases including Pythium, making a bad problem significantly worse.
The pest is particularly common in peat-free composts, which tend to stay wetter near the surface and create ideal breeding conditions. A single female can lay up to 300 eggs, and with a life cycle of just 28 days from egg to adult, populations build quickly, often getting out of hand before gardeners realise the larvae are the root of the problem.
