Just like with humans, good health care is of top importance. This includes timely worming and lice and mite control along with vaccinations. While it is soothing to watch a flock of free range hens scratching in your backyard, free ranging has its own set of health problems. There are many more opportunities for predators to snatch your birds and for parasites like worms, mites, lice, certain insects, slugs and snails to infect your flock with all manner of diseases and life threatening internal parasites.