Yup, I'm thinking those are maggots. I found those once in a big poop pile in my coop once too. Shortly afterward I cleaned the entire thing top to the bottom. Gross. After that, I started sprinkling diatomaceous earth (DE) on all the coop surfaces. Haven't had a problem with them since. I got it in a 50 lb bag at my feed store for like $15. You just have to make sure you get the food grade kind, NOT the kind that is made for use in pools. I have no idea how it is used in pools, I just know it's bad for the chickens. But then again, I would never use anything that isn't food grade, since I eat the eggs!