The Fall Army Worm (Spodoptera frugipeda) is part of the order of Lepidoptera and are the caterpillar life stage of a moth. They are native to tropical regions of the western hemisphere, from the United States to Argentina. They are regarded as pests and are known to wreak havoc with crops if left to multiply. Their name is derived from their feeding habits. The army worms are some of the most destructive pests to agricultural crop in the world. Once the food supply is exhausted the entire "army" of worms will move to the next available food source.