Place one to two inches of bedding in your mealworm bin. Sift out worms and replace the bedding when the bedding turns to powder. If your mealworms pupate into the adult beetle do not change the bedding as it will contain eggs of future worms. Just leave the bedding sit until you can see small mealworms and then sift into new bedding. Add bedding as needed until the mealworms are big enough to see and sift out.