We bought a couple of these oilers a few weeks back to try and control the Flys. I can tell by the looks of the socks they've been using them but haven't actually seen the cattle rubbing yet. I have noticed less Flys on the cattle and they seem to be spread out grazing better. Really hoping these things work. I figure it'll take a few months for all the cows to get used to them. Anyone have any experience with them?