The Monarch Butterfly is easily recognized by their bright orange wings with black and white markings; resembling a stained glass window. When resting or feeding, the underside of the wings are visible displaying a drabber orange color. The males have a black spot on each of their hind wings; scent glands used to attract the female Monarch for mating. They use their antennas to smell flowers and a tube, called a proboscis, to suck water, and nectar from flowers. The Monarch’s wing span is about 3 1/2 to 4 inches. Monarch Caterpillars can be identified by their many yellow, black and white bands around their bodies.
After mating, the adult female seeks out the milkweed plant to deposit her pinhead sized eggs. She can lay 300 to 400 eggs, in the wild, over a period of 2 to 5 weeks. The caterpillar feeds exclusively on the milkweed that provides sustenance and, for protection, a toxin that deters predators from eating them. The adult Monarch retains this toxin. The bright coloration is a warning-signal to would be insect-eaters that the adults are toxic, as well.
The eggs, once laid, will hatch within about 3 to 5 days. The caterpillar, in the larva state, lasts for about 2 weeks when it begins the stage called instar during which time the caterpillar goes through 4 to 5 moltings, shedding its skin, so it can grow in size. After the final instar it will become a chrysalis or pupa by spinning a protective silk cocoon around itself. The caterpillar then begins the remarkable “metamorphosis” where in which it transforms itself into the beautiful butterfly we know, over a 9 to 10 day period. The final stage of the Monarch’s life begins when it emerges from the cocoon. The cocoon hangs upside down; using gravity to help them pump fluid into their soft wings, soon after they are free from the cocoon. Within 3 to 4 hours the wings harden and the butterfly is ready for flight.
In late summer and early fall, Monarchs that were born in southern Canada and the northern United States begin a journey, that none of them have ever experienced before. They begin by gathering at the Texas-Mexico border. The perilous migration can encompass as much as 3,000 miles or more from beginning to end, for the most northern butterfly. This trek brings them to their overwintering home in the mountainous areas in the eastern part of the State of Michoacán and the adjoining State of Mexico, about 100 km northwest of Mexico City, Mexico. Weather permitting, they fly on thermal winds, the same way as migrating birds do. The Monarchs do stop at various locations to rest and feed and if the weather is too windy or rainy, that will throw them off course, they will wait until conditions are favorable, up to a week or more. Many of them will die on the way south, they can be eaten, they can encounter insecticides from farm fumigation, find it difficult to find a hospitable location to feed as the natural wild flowers have been replaced by urbanization, amongst other hazards.