I use it in a spray bottle for flies and it does keep them off for a time. I also rinse my horses off with vinegar. I tried it in their water but they wouldn't drink it so did away with that idea
I've used the mineral block and it does work the only thing I don't like about it is the thought of the chemicals that might be in it. Vinegar is a natural antiseptic so I keep lots of it around my house. I really like the fly predator where you sprinkle female wasp on your pasture, it doesn't hurt animals or humans. I also use skin so soft from avon with part water and part vinegar and the horses smell so nice afterwards.