About 3.5 weeks after a fly lays its eggs new flies appear. Depending on the sex, they live for 10 to 16 days. During this period flies can cause a lot of damage, mainly by carrying spores. Around 150 spores can attach to each leg and with six of them an adult fly can transport 900 spores 24 hours per day. If the fly population is not controlled properly, other hygiene measures will not be effective either. You’re simply fighting a losing battle.
It’s vital that flies are kept under control right from the start. A well-sealed growing room is measure number one. But achieving 100 % tightly closed doors is not always easy. Misters or a curtain of water droplets during filling can also help prevent the entry of flies.
Hang up yellow fly traps in the central aisle near the lamps to catch any flies that manage to enter the room. This will also give you some idea of how large the fly population is. Attach the traps close to the lamps and leave the lights in the middle on – in any case during the preparations. Especially in the spring, it’s advisable to regularly change some or all of the fly traps before filling so you have a better indication of the number of flies present. If the population swells despite these measures, treat the rooms immediately after filling and before cook out.
Jos Hilkens, AdVisie ‘The mushroom cultivation advisors’