Migration of the Monarch Butterfly
Monarch butterflies are not able to survive the cold winters of most of the United States so they migrate south and west each autumn to escape the cold weather. The monarch migration usually starts in about October of each year, but can start earlier if the weather turns cold sooner than that.
Monarchs like to hibernate
in the same trees every year.
The monarch butterflies will spend their winter hibernation in Mexico and some parts of Southern California where it is warm all year long. If the monarch lives in the Eastern states, usually east of the Rocky Mountains, it will migrate to Mexico and hibernate in oyamel fir trees. If the monarch butterfly lives west of the Rocky Mountains, then it will hibernate in and around Pacific Grove, California in eucalyptus trees. Monarch butterflies use the very same trees each and every year when they migrate, which seems odd because they arenít the same butterflies that were there last year. These are the new fourth generation of monarch butterflies, so how do they know which trees are the right ones to hibernate in? Monarch butterflies are the only insect that migrates to a warmer climate that is 2,500 miles away each year.
The Monarch butterfly migrates for 2 reasons. They can not withstand freezing weather in the northern and central continental climates in the winter. Also, the larval food plants do not grow in their winter overwintering sites, so the spring generation must fly back north to places where the plants are plentiful. Would you like to help track monarch butterfly migrations? Visit Monarchwatch for lots of information on tracking migrations with a color map.
The monarch overwintering sites are under threat because
of people cutting down their favorite trees to build roads, houses and
farms. What will happen to the monarchs if they do not have their special
trees to spend the winter? There are groups that collect money to save the
important trees and educate people about monarch
conservation. You can learn more about helping