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Hi Stormuk69,
Thank you for your reply! Did you try the fly trap? Can be fun to set it with the help of kids ! Feel free to let me know if you do .
I like your wide-ranged posts! Have a nice day!

It wasn't the Bananas in the end it was the tub of Peaches. They had rotted on the bottom. Fresh from the store as well. I'm sure they must lay eggs in the Fruit and then it hatches as they appeared from nowhere !! We don't tend to get them in the UK very often.