So we use fly predators in our barn and have little or no issue with flies, the problem for me comes when i ride out, once we get on to neighbours land or if we are staying at friends these flies drive my boy mad. They land on his nose and eyes while we ride and she goes crazy shaking his head, this isn' t too surprising given that he got bitten in the gap between his ear and eye by a real big one and it swelled up beyond words which was not comfy for him, he rubbed it raw and got an infection which was hard to clear.  
I bought a "net relief mask" which was meant to keep the flies away but one of the got under it and made the whole situation worse. Fly spray doesnt seem to help so I am getting to the stage of riding only in the fields on my own land.

Have you tried anything that works? Any ideas at all?