Sciarid flies, commonly known as fungus gnats, are small dark flies often seen around moist growing media in protected crops. While the adults are mostly a nuisance, the larvae feed on plant roots and organic matter in the growing media, which can damage young plants and seedlings. Root feeding can reduce plant vigour and increase the risk of disease.

• Use yellow sticky traps positioned near the crop canopy to monitor adult fly activity
• Inspect the growing media for small translucent larvae with black heads
• Look for signs of reduced plant vigour or poor root development, particularly in young plants
• Monitor regularly in moist growing conditions, where sciarid flies can develop quickly

Regular monitoring helps detect infestations early and prevent populations building in the growing media.

Sciarid fly larvae can be controlled using beneficial nematodes and predatory mites that target the pest in the growing media. Introducing biological controls early and maintaining good monitoring helps reduce larval populations and protect plant root systems.