Among the colorful arrivals during fall on the Coast are the monarch butterflies winging their way south for the winter.
These beautiful, Halloween-colored creatures travel across the Gulf of Mexico heading for their retreat in the oyamel trees of Michoacan.
Some of these remarkable lepidopterans will fly from Canada to their rating grounds; a distance of over 5000 kilometers. To give you an idea of just how far that is, a human adult would have to travel 450,000 kilometers or 11 times around the earth. You would do the vast majority of the trek without food or water.
The reason for this annual migration is obvious. They can’t survive the winter in most of North America. How they manage to navigate has been a matter of conjecture for over 100 years. It could be an instinctual orientation to the sun or stars. Perhaps an alignment along the Earth’s magnetic field or a combination of factors. We just don’t know. Whatever it is, they manage to do it year after year.
Once the monarch arrives deep in the mountains of Michoacan, they cloak the trunks of fir trees and hang on the limbs in clusters of tens of thousands. Estimates of upward of 250 million monarchs over-winter there. Entomologists didn’t discover this until 1975. Of course, the local residents were well aware of the phenomenon.
Their arrival coincides with Dia de los Metros (the Day of the Dead) in early November. The people of the region believe that they are the returning spirits of dead children. Their departure marks the time for local farmers to plant. The government of Mexico has set up numerous sanctuaries for the Mariposas monarchs in 1986. Since, these “holy groves” have become popular for excursions from Mexico City with up to 20,000 visitors arriving on holiday weekends.
Just as amazing as their flight to Mexico is their return trip. In late February or early March, as the days grow warmer and longer, monarchs leave their mountain hideaway and begin their arduous return. During their stay in Mexico the monarchs do not eat. They take in water and that’s all. The ones that survive the return trip north will die within a few weeks of their arrival on the Coast after laying their eggs on milkweed plants. It will take three or four generations for them to reach Canada.
Because of deforestation of their resting sites in Mexico, pollution and significant reduction in their most plants, monarchs are under serious threat. If you want to attract monarchs and other flutter bus to your home, grow some brightly-colored flowers for the nectar and pollen they need.
When the monarchs come back in the spring, they’re going to be looking for milkweeds on which they can lay their eggs. Milkweeds are readily available at most garden centers and are very easy to grow. They need no special care and can even survive our normal summer droughts.
Enjoy the flight of these extraordinary creatures for the next couple of weeks. They’ll be gone before you know it. Vuela seguro, mariposas.
Tim Lockley, a specialist in entomology, is retired from a 30-year career as a research scientist for the U.S. Department of Agriculture. For answers to individual questions, please send a stamped, self-addressed envelope to Tim Lockley, c/o Sun Herald, P.O. Box 4567, Biloxi MS 39535.