Non-toxic fly spray?

[only_me]

As horse is currently confined to his yard courtesy of the shitland, he has started to rub his tail from all the flys/midges. He's never rubbed tail before as normally lives out so can escape from them.
I caught him under a thick metal chain scratching his shoulders as well (bearing in mind he's 17h...) just swaying backwards and forwards - he wasn't stuck, he was having a good itch & when finished he calmly extracted himself

Normally I use power phaser, as I find it the most effective fly spray, but think it's quite chemically from the smell & don't want to risk it on the cuts/stitches.
Any ideas on a just as effective fly spray that is non-harmful?

 

[Sleipnir]

Neem oil! You can mix it with coconut oil if you find the smell to be too vile, but it's really good against flies.

 

[only_me]

Is neem oil hard to get off the skin? Need it to be more of a spray I think