Monarch Migration

Of all nature’s global migrations, there is none more amazing than that of the monarch butterflies. Their story spans three countries and covers more than 5,000 miles, round trip. It is the single longest migration of any insect heading for warm climates.

Similar to birds that head south for warmer climates in autumn and winter, the monarch butterfly migration begins in Canada and the northern and eastern United States. Depending on weather conditions, the migration starts in early October, but if cold weather conditions come early, so too will the migration. Watching the monarch migration on a sunny autumn day is a glorious sight and one of nature’s great displays of art.

Interestingly, this migration is determined by the Rocky Mountains. Monarchs that are born east of the Rockies head south to central Mexico’s oyamel fir trees while those born west of the Rockies make the eucalyptus trees of southern California their winter home.

The monarch’s life cycle is a unique event in the sense that there are four stages to each life cycle and also four generations within a year. The life cycles are the egg, caterpillar ( larvae), the chrysalis (pupa), and the butterfly in its adult stage.

The four generations begins with the fourth generation of butterflies that have hibernated during the winter. Coming out of hibernation they seek a mate for the migration north and east in search of a place to lay eggs. This is the beginning of the first stage and first generation of the monarch’s new year.

By March and April the eggs have been laid on milkweed plants. The eggs hatch in about four days and then baby caterpillar begins its diet of milkweed plants.This plant is crucial to the monarch while in it’s larvae stage, as this is the only plant it will eat during this period. In two weeks the caterpillar is full-grown and attaches itself to a leaf or stem to begin the chrysalis transformation known as metamorphosis. This stage lasts about ten days and then the butterfly emerges. The new life of this first generation butterfly lasts for two to six weeks and then dies after laying eggs for the second generation.

This amazing process repeats itself for the second and third generations. The second generation is born in May and June, the third generation in July and August, each dying two to six weeks after becoming a butterfly.

The fourth generation of monarchs has a story to tell, and they tell it well with an astounding accomplishment. Born in September and October through the same process as the first, second, and third generations, this group is given a lease on life in the form of six to eight months (note the three previous generations only have a two to six week life) so that it can participate in the great monarch butterfly migration to the warmer climates of California and Mexico. The cycle is complete upon their arrival to their respective winter hibernation homes. Of interest is the fact that these fourth generation butterflies will nest in the exact trees that all previous fourth generation butterflies nested in.

The monarch migration is decided by two factors. First, freezing temperatures are lethal to their population. In fact, their winter home in central Mexico has seen massive die-offs due to freezing temperatures. Second, the food plants necessary to support the larval stage do not grow in their winter hibernation sites, making a return migration to traditional feeding grounds the following spring a necessity.

As with much of the natural world’s interaction with the human species, habitat loss is a great concern for the monarchs. Milkweed, the one plant necessary for their survival, continues to suffer the effects of land development, human encroachment, and in recent years, wildfires.

Because of the milkweed loss, a move is underway to help ease some of the stress created on the monarchs. Conservationists are involved in milkweed restoration projects through land protection and education awareness programs. It’s very easy to plant milkweed in your own backyard, combined with other plants that the monarchs use during their life cycle. Theirs is a liquid diet, so flowering plants are a great addition to your own butterfly habitat. Also, if your garden does not have fruit trees, consider feeding the butterflies old fruit. They love the liquid contained in softened fruits. Juts throw the fruit in your garden and you’ll soon see butterflies covering it. Not only will you attract monarchs, but you’ll soon see a variety of butterflies in your garden, assuring you and your garden a great butterfly display.