I just looked it up. It says not to use near children or animals. So where in your barn do you put it?
I had a friend with bad flies and she bought some predator stingless wasps. Almost completely eliminated the trouble!
I don't have fly problems, but the mosquitoes are awful this year - they're eating the goats alive - and us, as well. I finally bought an all natural horse spray. It smells good and it's the first spray I've tried that the goats don't scream and run from. ;-)
I brush the does and spray it on them, then I spray the barn walls before I put in their hay and water. It seems to be helping. Naturally, I can't recall which product it is. I got it at Agway and it was the ONLY all natural product they carried as a repellant.