Maybe you could give the heap a good mix then cover the surface with a good layer of paper and leave it for a few weeks to settle down. Don't open the lid for a bit and maybe the flies will die off without getting any new food or access to the existing (as it's covered). Don't give up, when you get it going it's dead easy so you're on the harder bit.

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Some of us live in the past, always talking about back then. Some of us live in the future, always planning what we are going to do. And, then there are those, who neither look behind or ahead, but just enjoy the moment of right now.

Which one are you and is it how you want to be?