Occurrence and Control of the Giant Phorid Fly Pest on Reishi Mushrooms

Megaselis halterata Wood, synonym common phorid fly, Wolsin phorid fly. Belongs to Diptera, Phoridae.

1. Morphology and habits: adults are active, black to dark brown, body length 2-3 mm, antennae short, with arista. The mesonotum is rather strongly raised. Larvae are maggot-shaped, pale yellow to white, with a pointed front end of the head, the body has 11 incisions, the rear end is obliquely rounded, with 2 papillae, posterior spiracle type. Pupae brown. Eggs white, oval, egg stage about 7 days.

Adults have strong phototaxis, are frequently active above 17°C, and lay eggs on the growing substrate near the mycelium; at 24°C a generation is completed in only 15 days, and they occur in large numbers in spring and summer.

2. Damage situation: the larvae damage the mycelium; generally phorid fly larvae attack close beneath the casing soil and concentrate to feed at the mycelium where small primordia have formed, causing the fruiting bodies to die. When humidity is high and ventilation is poor, the occurrence is severe.

3. Control methods

(1) Install insect netting on doors and windows to prevent adults from flying in to lay eggs, and at the same time do a good job of keeping the site clean and sanitary.

(2) The occurrence period of phorid flies is uneven, and they bore into the soil and substrate to cause damage, so control should focus mainly on killing the adults. Note that the casing soil humidity should not be too high, to reduce mass occurrence of phorid flies.

(3) When occurrence is severe, before removing the bags or after harvesting the reishi, spray 1500-fold diazinon; if damage occurs during the fruiting period, spray with 3000-fold deltamethrin solution.