The monarch is a member of the brushfoot family. There are around 5000 different species of brushfoots in the world with over 200 of them living in North America. The brushfoot family got its name because their front legs are shortened and covered with hair giving them the appearance of a small brush.
Monarchs larvae, or caterpillars, only eat plants from the milkweed family, particularly common milkweed. Ingesting the toxic sap from the milkweed makes both larvae and butterfly unpalatable to many predators, an exception to this is the dragonhunter dragonfly.
Here in the north monarchs typically have two broods per year. The second brood will migrate south in the fall down into the mountains of central Mexico, monarchs on the west coast usually migrate to southern California. When they reach their destination they will hibernate in mass groups until spring when they will awaken and mate and die. Eventually their offspring will make it back north.