The monarchs, Danaus plexippus Linnaeus, are among the best known of the world’s butterflies due to their remarkable ability to migrate, wide distribution, and charismatic appearance. The last Pleistocene glaciations in North America instigated migration to Mexico in the east and to the Californian coast and deserts in the west. In the western U.S., the overwintering colonies are smaller and more numerous, while in Mexico, they are few but more spectacular, with billions of butterflies concentrating in one spot.

Adults are strong fliers and can fly for 11 hours straight. In the fall, enough fat is stored in the adults to allow a continuous 1000 km flight without feeding. Some make a journey of a total of 4000 km to reach overwintering sites in the Sierra Madre de Oriente, where they settle inside the coniferous forest of the state of Michoacán. Monarchs also fly across the Gulf of Mexico with overwater flights of 600 km.

Monarchs are not endangered as a species due to many sedentary populations in the south of its range. However, the deforestation around their overwintering sites in Mexico puts the northeastern population of monarch and the remarkable phenomenon of migration in danger. Planting milkweed in your yard and garden helps support the monarch population. View the monarch caterpillar here!

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