I too live in East Texas (NE really--Upshur County). I tried the XP 820 fly tags last spring and the flies just disappeared--it was almost scary! They are working this year too, will rotate to whatever the company that makes them recommends next year. I put two tags per cow, one per calf (I put them on the back of the ear). Require a Y Tex tagger. I replaced them after three months last summer and the cows were blissfully fly-free all season long. They sure have made my life easier, had tried all the sprays, rubs, etc.......these tags really work, it's a fairly new chemical I believe. I got mine from Livestock Concepts. And these tags are dry and don't smell, I at first thought there was something wrong with them but that's how they are. You'll love them.