Fruit Flies in polytunnel

[Mark_Riga]

I've got 2 nectarine trees in a polytunnel and a lot of the fruit is being damaged before it ripens. I think the culprit is fruit flies. I had to pick about 3kg of fruit that was going to rot but was still not quite ripe. I have just put a fig in there as well now and was wondering if anyone has a good way of preventing the pests from getting in a polytunnel in the first place or dealing with them when they appear? I've put fleece round some of the branches and some traps up but I think too late for this year.
The nectarines I picked were very nice in a pudding but not how I envisaged eating them.

[ameno]

Fruit flies aren't interested in whole, undamaged tree fruit. They will only go after damaged or rotting fruit. So if you have fruit flies eating your fruit, then there must be something else damaging the skin first to allow them entry. Perhaps they are splitting due to erratic watering? Or maybe wasps are eating them?

I've never had fruit fly problems with fruit, but I have had problems with them in the house before, and in my experience the only way to get rid of them is to cut them off at the source. That is, to remove or cover all potential food sources.

Maybe you could try tying a plastic bag around each individual fruit once they begin to ripen?

[Mark_Riga]

I think I need to check whether this, the Spotted wing drosophila, is arround.

https://www.rhs.org.uk/Advice/Profile?PID=852

[Jungle Jane]

Someone else had fruit fly problem on their cherry,they can overwinter close to the fruit,do you think they overwinter in the pots. There’s nematodes for fruit fly but I don’t know how well they work.