Thousands of Monarch Butterflies Wintering in Southern California and Mexico from November to February where they will make thier journey back up into the United States and Canada. Most monarchs live about four weeks but the fifth generation born around Sept/Oct live for about six months(also sometimes referred to as Super Monarchs because of the long life compared to the normal life span) and these are the butterflies that leave in early fall to go to the wintering grounds to mate and wait for warmer climate in the upper United States and Canada. They are also known as the Milkweed Butterfly for they only lay their eggs on the milkweed plant..This plant is poisonous and the toxins they ingest make them unapealing to eat by predators... The Viceroy Butterfly takes advantage of this and mimics the appearance of the Monarch to keep predators from eating it..As they look very similar except for a small black line across the bottom of their wings..The reason they cluster like this in the trees is to regulate heat so they stay warm. They can not fly in tempertures of 55 degrees and lower. Most of the Monarchs travel down to Mexico but there are three main areas in Southern California where large numbers of the wintering butterflies can be viewed. Pismo Beach(just south of San Luis Obisbo)/Pacific Grove(Monterey) and Morro Beach