It’s that time of year again. Across the country, wildlife from the humblest to the most grand is all a bustle, shoring up their stores for the harsh economy of the months ahead: chubby, sleepy-eyed bears lumber about, squirrels frantically stuff acorns into soon-forgotten divots and knotholes, and birds answer the silent call of centralized flock and flight—remarkable to be sure, and yet perhaps not the most impressive of fall’s preparations. For among these more conspicuous displays flit and flutter the unsung heroes of the season: thousands of delicate, black and gold beauties, barely more than the size of a playing card, flex their delicate wings in preparation for the journey of a lifetime—the monarch butterfly’s three-thousand mile annual migration from their summer homes in the North to the warmer latitudes of the South.
Remarkably, this final stage of the monarch butterfly’s life is not so much an isolated feat but a denouement, a spectacular finale to a full season of spectacularly unlikely life-stages: each phase of the monarch’s life-cycle is more impressive than the next. It begins each year in May, when the first monarchs return to their Northern homes to search out among nature’s great variety the one plant that will sustain their progeny: the humble milkweed. Once the plant has been discovered, the female will deposit a delicate strand of over 1,000 single, cream-colored eggs along the underside of the plant’s leaves, often leaving behind a string of eggs that cumulatively bear a mass that equals her own.
From these eggs will emerge larvae, or caterpillars, the happy stage in a monarch’s life in which its only duty is to eat. Taking advantage of its convenient placement on the milkweed, the caterpillar will relentlessly munch its way up the stalk, blithely chomping in a spiral path so as to miss the oozing sap that would entrap it. Within two weeks, the caterpillar will have increased its size by 2000 times, grown tentacles (which bear the charming moniker “stinkhorns”), and changed from standard-issue larvae-green to brilliant bands of black, white, and yellow. The caterpillar will molt five times to accommodate its rather admirable weight-gain, leaving its shed layers behind until, as if on cue, it attaches its bottom to the milkweed stalk with silk, hangs upside down, and encases itself in the blue-green chrysalis of its final molt.
For ten days, the cocoon will hang from the plant, stoic and silent and utterly boring to the outside observer, but within the tightly wrapped chrysalis, a mind-boggling transformation takes place. What went in as a horned and tentacled banded caterpillar will emerge a fully-formed monarch butterfly. When it breaks free of its encasement, the monarch will spend the afternoon expanding and contracting its wings, pumping fluid through the inside and drying off the outside of its delicate new appendages before flitting off to start the process all over again.
With the first three generations of a year’s monarchs, each follows much the same process as the one before, the egg, larvae, pupa, and adult stages passing in a relatively consistent lifespan of two to six weeks. The fourth generation, however, takes a spectacular divergence from the pattern of its parents; it will live anywhere from six to eight months, long enough to traverse the hundreds—sometimes thousands—of miles that lie between its birthplace and the safe warmth of southern California and Mexico. Once it arrives, our monarch will pass the winter in thick clusters of its kind, then make its way back across the miles to its home where it mates, lays eggs, and dies.
This fourth and final generation of the year’s monarchs are due each fall, emerging from their eggs throughout September and October, utterly unaware that the weight of their species’ survival rests on what will someday be miraculously transformed into their trademark golden wings. From humble grub to stunning butterfly, across thousands of miles and back again, the journey of the monarch reigns supreme, a course that certainly earns it the right to be called the king of the butterflies.