In different phases of its life, the body structure of the monarch changes. At the larval, pupal and mature (or imago) stages, the butterfly shows completely different structure, size, color, habitat, behavior and biological systems.
Monarchs have very interesting characteristics that set them apart from other butterfly species. In the space of a year, monarchs have four different generations. The first three generations have an average life span of five to six weeks, but the fourth generation is quite different, in that it sets off on a journey lasting about eight months and stays alive until this journey is complete.
The life of any given monarch starts when the female lays her eggs on a milkweed plant. The tiny caterpillar hatching from each egg feeds on the leaves for a time and each one quickly grows. It sheds its skin five times as it grows during the larval stage. Its skin is shed for the last time as it passes to the pupal stage and becomes a green chrysalis, which hangs on the stem of a leaf by a fine but very strong thread. Within this chrysalis, the insect continues its development before emerging in the form of a brand-new beautiful butterfly. Its wings are crumpled at first, but as hemolymph (the blood-like substance of insects) fills its body and wings, they enlarge, and the monarch is ready for flight.
The journey of migration begins from different centers in Southern Canada and continues south. One group arrives in California and another further south in Mexico. These different monarch groups meet mid-route as though they have received orders from the same headquarters and continue their migration together.
The butterflies do not set off at just any time, but begin their journey at the autumn equinox. After flying for two months, they reach the warm forests in the south, where trees are covered by millions of monarch butterflies. Here the butterflies rest, taking no nourishment for four months, from December to March, surviving on the fat they have accumulated in their bodies, drinking only water.
Flowers that open in the spring are important for monarchs, and after their four months of going without food, they drink nectar, and store the energy they need for returning to North America, and mate at the end of March, just before setting out on the journey. Just at the equinox, when day and night are of equal length, the colony starts flying northward. Completing their journey, they bring forth the next generation to ensure the continuation of their species.
The newly-hatched caterpillars are the first generation of the year and will live for approximately one and a half months, after which come the second and third generations. With the arrival of the fourth generation, the journey begins again. Again, this generation will live six months longer than the others, and in this way the chain will continue.
Why is one generation in four born with the characteristic of living six months longer? Why are these particular longer-lived butterflies hatched just ahead of the winter months? Why do they begin their migration at the equinox, and how can they make this fine calculation? How does a newly emerged monarch know the way, on a route it has never flown?
The answer to all these questions is that monarch butterflies have been created in accordance with a perfect migration plan and conform to it to the last detail. If there had been the smallest flaw in this plan, from the time these insects came into being, monarchs would not have completed their migration. Winter would have killed them, and monarch butterflies would have become extinct.
Of course these insects have been created, and the incredible migration they make each year has been taught to them. The Creator and Ruler of all forms of existence, God, Lord of the Earth and the heavens, is the author of their wonderful creation.