The monarch butterfly, scientific name Danaus plexippus, is a large, orange-and-black butterfly, common to much of North America. It is famous for its annual migrations to and from wintering grounds in Mexico and California, see National Geographic, vol. 150, no. 2, August 1976.
The monarch starts life as an egg laid by the adult female on a leaf of the common milkweed plant, Asclepias syriaca. It is about the size of the head of a pin. When the egg hatches 3 to 12 days later, the tiny yellow-, white-, and black-striped worm-like larva, or caterpillar, has eight pairs of stubby legs for crawling about, and mouth parts designed for chewing leaves, which it does, voraciously. But only the leaves of the milkweed; no other plant will do. Now the milkweed has a white, sticky sap that is highly toxic to other animals, but does not affect the caterpillar at all, except to make his body, in turn, highly toxic to predators like birds that might like to eat the caterpillar for breakfast. And the birds, being no bird-brains, know to leave him alone.
As the caterpillar eats and eats, it grows. Soon it gets too large for its skin, so the skin splits and out crawls the caterpillar with a new and larger skin with room to grow. For about two weeks this is what the caterpillar does: eats leaves, grows, sheds its skin, eats more leaves, grows more, sheds its skin. It will do this five times.
Finally it stops eating, finds a protected spot, hangs upside-down, spins a silk attachment, and sheds its skin one more time. But this time what emerges from the old skin is not a larger caterpillar, but a compact package with no legs and no eyes, and no visible body parts, called a pupa, encased in a chrysalis. It is not multi-colored like the caterpillar, but is bright green with golden-yellow spots.
No further movement is observed, but inside there is much movement. The heart still beats, but the rest of the internal organs resemble green jelly, as the entire mass reshapes itself into a completely different creature. The green color darkens, turns brown. To an uninformed observer, the package may appear dead. But gradually the color modifies as the chrysalis turns clear, and orange and black areas can be seen, the colors of the adult butterfly.
Finally, after about two weeks, the chrysalis splits open, and an adult butterfly emerges. It has six long legs, a mouth that is a long coiled-tube proboscis used for reaching into flowers to drink nectar, and two pairs of shriveled wings that rapidly expand as fluid from the body is pumped into their veins. As they expand, the butterfly slowly fans them back and forth with newly-acquired flight muscles until they are dry, so that the fully-extended wings are stiff, ready for flight.
Soon the butterfly flits off into the sky, and may be found in someone's flower garden, drinking nectar with its uncoiled proboscis, or flying overhead looking for a mate to start the whole cycle all over again.
Your assignment as an evolutionist, should you accept, is to explain HOW the above transformation could POSSIBLY have developed by accident, by a collection of genetic mistakes, with NO PURPOSE, NO INTELLIGENCE involved, guided only by survival of the fittest, as some primitive creature without wings gradually evolved into a flying butterfly.
Which stages of the above process, called complete metamorphosis, can you put off for a while because those accidents haven't occurred yet? If even one enzyme is missing, how does the egg-to-larva-to-pupa-to-adult transformation happen? It must all be present and functional, in the right timing and sequence, or the creature dies. It all works, or none of it works.
But don't give me some "just-so" story; I want scientifically-feasible explanations that a geneticist wouldn't laugh at as ridiculous. And don't call it "Nature's miracle", unless you are willing to acknowledge intelligent, creative design in the god you call Nature. ...This article will NOT self-destruct.
"Mission Impossible: the Monarch Butterfly"