Harvest castings can be fun and easy. The worms should be in the bedding you started them in for about three months. Dump the contents of the bin on a piece of plastic or paper, and shape the pile into a cone shape. Place a bright light over the pile and all of the worms will burrow. Slowly begin removing the castings making sure the worms are burrowing, and not being removed with the castings. Repeat the procedure until all of the castings are removed, and all of the worms are in a pile. Now you will be able to see how many worms you have, and easily divide them for making new bins. This method is great for the person using bins that can be moved about. The small greenish, or yellowish drops you will see in the castings are worm capsules. Try to harvest these when you see them. They each contain 4 to 20 baby worms.