Wednesday, April 07, 2010


A few days ago, on one of those unnaturally warm days of this unusual spring, I encountered a woolly bear caterpillar humping across the path, just emerged from hibernation. I picked it up, held it in my hand, and pondered for a while the incredible story of its life cycle.

Perhaps I saw this same creature in the fall, trundling along the same path, looking for a cozy place to spend the winter, curled under leaves or logs like a sleeping kitten, snoozing in frozen slumber. Now it wakes, has a bite to eat, then rolls itself into a pupa, using its hairs to make the cocoon, lacing them together with silk. Two weeks later, an Isabella tiger moth emerges, presto-chango, like a magician's trick. A black-and-brown woolly bear goes into the box -- a wave of the wand -- a yellow-winged tiger moth emerges. Somehow, the creature has remade itself, rearranging its molecules, from crawling fuzzball to airborne angel.

In few animals is the transformation so stunning. An insatiable leaf-eating machine becomes a sex-obsessed nectar-sipper. Shape, color, internal organs, mode of transportation -- all changed. It's as if an elephant became a swan, or a rattlesnake became a parakeet.

There are clusters of cells in the larval caterpillar that are destined to become anatomical features of the adult moth, dormant, awaiting a chemical signal that will make them surge into activity. The warmth of spring releases hormones from glands in or near the brain. Previously dormant adult cells begin to multiply. They take their nutrients from superseded larval cells, which are transformed into a kind of nutrient soup for the benefit of the growing adult organs. The woolly bear's six stumpy front feet are turned into the tiger moth's slender legs. Four bright wings develop, as do reproductive organs. Chewing mouth parts become adapted for sucking. In two weeks, the rearrangement of atoms is complete. The chrysalis breaks.

There's no way to think about this without gasping for breath. It's one thing to understand the biology, at least that part of it that we know something about: DNA, hormones, gene expression, and all that. But knowing the biology only makes the metamorphosis all the more breathtaking. Not magic at all, but a fierce, inextinguishable force driving the universe, Dylan Thomas' "green fuse."

Later that day I was in conversation with a good friend, a Catholic priest. He was telling me about celebrating Easter Mass alone, which he considered a rare and happy indulgence. Just himself and the Eucharist, and a fiercely felt "encounter with God."

"You encountered God," I said, a little enviously. "I encountered a caterpillar."