Mushroom Cecid Fly

📖 Description

The mushroom cecid fly, Heteropeza pygmaea, is one of the most unusual pests in Indian mushroom cultivation. Unlike sciarid and phorid flies, which reproduce sexually, cecid flies exhibit paedogenesis — larvae themselves reproduce viviparously (giving birth to live daughter larvae) without ever passing through an adult stage. Each paedogenetic larva produces 8–15 daughters, and under favourable conditions (saturated casing, 22–25 °C), a single founder larva can give rise to 50,000+ larvae per m² in just 3–4 weeks. The orange-yellow larvae feed on mushroom mycelium at the casing-compost interface, damaging pin-set and reducing yields by 15–30% in heavy infestations. The larvae are also a major contaminant of harvested mushrooms — they crawl up the stem and lodge between the gills, where they are difficult to wash out and are a frequent cause of consumer complaints and consignment rejection. Paedogenetic reproduction means that even a single infested batch of spawn or compost can seed a full-blown outbreak; larvae can also survive desiccation and mild heat, making them difficult to eradicate from a contaminated house. Adult cecid flies are rarely seen — they are weak fliers, and most reproduction occurs in the larval stage. In India, cecid fly infestations are most commonly reported from the Sonepat and Solan mushroom belts, particularly during the monsoon and post-monsoon (July–October) when humidity is high and casing is harder to keep dry. The single most effective management practice is keeping casing moisture at 60–65% — even one flush of over-wet casing can trigger an outbreak. Annual Indian losses are estimated at ₹15–25 crore.