I am so frustrated!! I thought I was treating aggressively and used all the advice I got here. Last week I started seeing poo that I thought might be suspect.....I have become a diligent poo checker after the last tape worm infection. I thought maybe i was just a doomsdayer...but today I have confirmation that there are in fact tapeworms in a couple of the droppings I found. last time, I found LOTS of worm ends and egg sacs in many or most of the droppings by the time I realized it. I have 18 chickens that free range, it is hard for me to tell who has them and who doesn't as well as who lays which egg. 6/24 wormed with Valaben, 1/2cc each 7/3 Valbazen again, same dosage. Not sure I noticed any change 7/13 Zimectin Gold, pea sized amount per chicken. By now there were only a few droppings with segments, but not sure which so I wormed all chickens a third time. I was without eggs for a month. Now i have had them less than a month and I have worms again. What do I do this time, and HOW can I keep this from happening again?? Is there a preventative I can give them?