X2, Judy.
I can verify there is *no such thing* as a "natural" wormer. Garlic, pumpkin seed, grapefruit extract... Nothing will work against worms except a chemical wormer. If anyone tells you differently, they haven't had a chicken die from worms while spoon feeding mashed garlic and pumpkin...
For worms, Valbazen once or twice a year is good. Valbazen gets every worm known to chicken-kind.
For lice and mites, Sevin dust them every once in a while as needed. I also sprinkle it around the coop when I change the bedding, and pour it in their favorite dust bathing spots. :)
MrsB