Phorids

Mushroom Phorids are about two-three mm in length and are hump-backed with inconspicuous antennae. They are brown-black in colour and when seen on surfaces they tend to scuttle around with a rapid jerky run. These flies are unable to fly when the temperature is below 54°F (12°C) and are therefore unlikely to invade a mushroom unit from November to March. The flies are attracted to the smell of mushroom mycelium and therefore pose a threat as soon as the crop is spawned.

The female can lay 50 eggs close to growing mycelium, and at a temperature of 24°C these eggs will reach the adult stage inside two weeks.

The larvae are white legless maggots with no black head and tend to have a blunt tail region. These larvae feed entirely on growing mycelium although some species can tunnel into mushrooms. Adults are usually annoying to pickers. In addition these flies can spread disease such as Verticillium.

1. Efficient composting and peak heating.

2. Exclusion of adults by filters and tight fitting doors especially during the first three weeks after spawning.

3. Disposal of stems immediately from the growing house, these should be dumped at a distant location. When the bags are emptied they should also be discarded well away from the farm.