Come Fly With Me - Monarch butterflies (Danaus Plexippus) in the Oyamel forest at the El Capulin sanctuary in Mexico city. The butterfly makes an annual 4,500 km migration from Canada?s Great Lakes region to Mexico. Scientists say that ancestors of the monarchs were tropical butterflies that could not survive long periods of cold weather. They never evolved the ability to tolerate winter and had to move to warmer locations. Most other temperate insects can withstand the freezing winter by entering a state called dispause.