What should I use as preventitive dewormer for my chickens and also what should I use to prevent lice or mites? I don't eat the chickens so a chemical based product is okay with me. I am a bit skeptical that natural remedies will work. I live in Southern California, so the soil is usually dry and sandy. I think I will probably treat them twice a year because of all the sparrows and lizards in the yard, plus they free range a few hours each day. They are currently healthy, happy and laying so I would like to keep them this way.