I worm by birds every 6 months as a preventative measure. I give them wazine in their water, then I wait about a week and do the pour on ivermectin. My chickens free range so they get into all kinds of stuff. When it comes to parasites I tend to err on the side of caution and avoid "natural" remedies because truth is...they usually don't work. I have found this routine works well and my birds never have worms or parasites.