Why worms, and what's up with their castings? If this is a question you are asking yourself right now, it's a good thing you are reading this, because I'm going to tell you why. First off, the reason I have so many red wigglers living in my compost piles is because I put them there. After realizing that vermiculture wasn't for me or my lifestyle, I set the worms free to eat the food in my compost piles and leave their casting behind, thus enriching the product that much more. Worm castings is just another way of saying worm poop, and as the worms digest the kitchen scraps, their castings (poop), enhance the compost anda create a rich fertilizer for your garden.