Diatomaceous Earth is a fine powdery substance that is made up of the crushed bodies of a single celled sea creature. It is one of the better natural choices for controlling certain kinds of bugs in the garden - soft bodied bugs, specifically. It will reduce the number of cabbage loopers, and is effective on many other kinds of insects as well. It looks and feels like talc, and is available in several forms. Look for the type intended for animal use, and then you can use it in the garden, and around pets to control worms (sprinkle it on food, and around where they leave their droppings). We used a duster to apply it in the garden, but you can use a large zip bag with a tiny bit cut off the corner. Get the bag full of air, pinch the hole in the corner loosely, and squeeze the bag toward the plant. With a bit of practice you'll be able to use this method as well as a duster.