Insect pests of mushrooms: Phoridae

Area of Expertise:

Adult phorids are slightly smaller (2-3 mm) but more robust flies than sciarids. They are darker in colour with a hump-backed appearance with no obvious differences between male and female flies.


Adult female phlorid
Adult flies tend to remain on the compost surface or in close proximity to the cropping area.  They are very active in the presence of light and have a characteristic rapid, jerky movement.

Phlorid larva
The flight of adult phorids is limited by temperature and they are unable to fly when air temperature is below 12°C.  Therefore, wild populations do not normally invade mushroom production houses between November and March and adults are most abundant in September - October.
Each female can lay up to 50 eggs in close proximity to developing mycelia.  Phorid larvae are off-white, legless maggots without a distinct head capsule (cf sciarid larvae).  The anterior region narrows to a point while the posterior is blunt with small protuberances.  An economic threshold for phorids has not been determined but it is estimated that 50-60 larvae/125g of compost would cause 0.5% total yield loss.

Phlorid pupa
The duration of phorid development is temperature dependent and may vary between 15 days (24-27ºC) to 50 days (16-21ºC).  Larval development accounts for approximately 1/3 of the development time and the remainder is spent in pupation.

Phorid life cycle

  • After mating, adult females are attracted to developing mushroom mycelia in spawned compost.
  • The compost remains attractive to adult females throughout the entire spawn-run period, and is particularly susceptible during the second week.
  • Mycelial development, which occurs following casing, renews attraction to adult females.
  • Each female can lay up to 50 eggs in close proximity to developing mycelia.
  • Duration of the life cycle is temperature dependent and will vary in relation to the environmental conditions associated with cropping periods.
  • Increased air temperatures associated with spawn-run and case-run periods facilitate life cycle completion in 24-26 days.
  • The lower temperatures following breaking and during cropping periods may extend the life cycle to 40-50 days.