Just bought some bulk Phaser from Hyperdrug, and also the cream version with the sponge, for his face. I've also bought some Tri-tec 14 but not used it yet.
I make my own up with Neem Oil and T Tree Oil and water (and a squirt of WU Liquid as an emulsifier for the Neem).
The best by far that my horse puts on is 'mud/soil' from the amount of rolling he does when he first goes out!! LOL I swear this is 'his' way of protecting himself from the biting critters!