I have no idea what it is! A wart? It is definitely skin, not a bug - I went back out to check again and take this photo. She is molting right now and I dusted her for lice yesterday because I found one under her wing. When looking her over today I discovered this strange little bump on her lower back above her tail base. She has always been very healthy and a great layer and doesn't act any differently. Should I be worried? Thankyou for helping! BTW - thanks to everyone hear for the great tips on treating lice! I am a fairly new chicken owner and I learn so many things here.