I did not worm anyone in the flock for almost two years. Then, I did it because I saw a worm in one rooster's poop, no other signs. Once a week, I usually give them chopped pumpkin seeds in their scratch or in oatmeal, which is a natural wormer, but not what you use if you have an actual infestation. No recipe for the pumpkin seeds (and sometimes buttermilk) in the oatmeal, just hulled unsalted ones I get at the grocery store. Chop 'em a little and throw them in there, couple handfuls or so.