As a newbie to raising chickens, I finally figured out what the little nub is on the base of the tail under the feathers, it's the Preen Glad! I have seen them several times, mainly when I am checking for parasites and dusting. My questions are, is it bad to dust the Preen Gland when treating for parasites, and my other question is some of my hens have what appears to look like small dirt flecks in the feathers around and on the Preen Gland, is this normal or am I seeing mites? I chose to post my question under this Forum since I wasn't sure if I am dealing with parasites or not. I must admit that I have had problems with poultry lice previously, but I know what they look like so I know that is not what I am seeing.