The Monarch Butterfly

Monarch Butterfly

The Monarch butterfly has a very large range that extends from Southern Canada south through the United States, Central America, and most of South America. They are also present in Hawaii, Australia, and the Pacific Islands.

When Monarch butterflies come up in conversation, we usually think of the 3,000-mile journey they make between Canada and Mexico east of the Rockies. What people often do not realize is that over a million Monarchs also make a western migration. Monarchs west of the continental divide over-winter along the coast of California. Although the winter roosts are not as large as their Mexican counterparts, these magical places may contain tens of thousands of gorgeous butterflies. Eastern populations winter in Florida, along the coast of Texas, and in Mexico, and return to the north in spring.  Each year the same migration paths are followed. Although, we don't know for certain how far they actually travel in a day, there was one tagged monarch that was recaptured 265 miles away from where it had been released the previous day!

Cluster of Monarchs on Tree

Ordinarily, each adult Monarch butterflies lives only about four to five weeks. But one of the many wonders of the Monarchs, and that which sets them apart from other butterflies, is the annual creation of a unique "Methuselah generation." As autumn approaches in their sites of migratory origin, a very special generation of butterflies is born. Unlike their parents, grandparents, great-grandparents, or even great-great-grandparents—all of whom had ephemeral lives measured only in weeks—this generation will survive seven or eight months. In human terms, given our average life span of 75 years, this would be like having children who lived to be 525 years old! This generation will perform the incredible feat of flying from Canada and the United States to central Mexico—after which they will again migrate to the north.

We breathe air into our lungs. Special red blood cells pick up the oxygen, and the arteries of our circulatory system carry the oxygen to the rest of our body. Unlike people, butterflies don't have lungs. Monarchs breathe through tiny openings on the sides of their bodies called spiracles. (The spiracles are in their cuticle, like our skin). The holes open into a system of tubes in their body (called trachea) that carry the oxygen all over their bodies.

Monarch Butterfly

The monarch butterfly is sometimes called the "milkweed butterfly" because its larvae eat the plant.  In fact, milkweed is the only thing the larvae can eat! The larvae feed on the plant leaves for about two weeks. Interestingly, milkweeds contain poisons. These toxins from the milkweed diet become the Monarch’s defense.  Most predators have learned that the monarch butterfly makes a poisonous snack. After tasting a Monarch, a predator learns to associate the bright warning colors of the adult or caterpillar with an unpleasant meal, and avoid eating them in the future.

Monarch caterpillar

After about two weeks of milkweed diet, the larva develop into caterpillars about 2 inches long. Soon, the caterpillars attach themselves head down to a convenient twig, they shed their outer skin and begin the transformation into a pupa (or chrysalis), a process which is completed in a matter of hours.  

The pupa resembles a waxy, jade vase and becomes increasingly transparent as the process progresses.  The caterpillar completes the miraculous transformation into a beautiful adult butterfly in about two weeks. 

When the butterfly finally emerges from the now transparent chrysalis, it inflates its wings with a pool of blood it has stored in its abdomen.  When this is done, the monarch expels any excess fluid and rests, waiting until its wings stiffen and dry before it flies away—to start the cycle of life all over again!

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