The caterpillars are falling down, crawling down, even as you read this, inching their way down the plant stems toward the autumn ground, to wrap themselves like origami inside their tiny leaf sleeping bags and wait for spring.

We think of autumn as the end of the line for butterflies, after the summer spent surfing heat and light. But autumn is the beginning of the butterfly dream time, of the strange insect journey to what they will become.

If art is strangeness married to beauty, as a poet friend once said, then butterflies may be nature's supreme work of art. In summer, they are light and beauty, blameless muses of insipid lyric and saccharine song. But the real life of a butterfly is beautiful in a truer sense -- hard, brief, incandescent as a sunset, beset by creepy predators, captive of a cycle of constant and violent change. Only one one-thousandth of the eggs laid by a female butterfly survive to adulthood.

And strangest of all: The butterfly is twice born. The first time, from the egg. The second, in the last half of its life, from the hard shell, the chrysalis, which it enters as a caterpillar and emerges from 10 days later, drenched with dark fluids, with jewel-like wings covered in iridescent scales that undulate in flight like the fins of a fish and give them enormous propulsive power. The ancient Greeks called the butterfly psyche, the same word they used for "soul." Except for the ugly duckling, there is no more powerful fable of metamorphosis.

Which may help explain why the United States is eight years into an unprecedented passion for butterflies, similar to the craze for bird-watching that erupted at the end of the last century.

Ten years ago, there were exactly two live butterfly exhibits in the entire country. Now there are dozens and dozens, and more opening all the time. There are butterfly houses, butterfly breeders to supply them and dozens of new butterfly clubs devoted to butterfly watching and conservation. There's even a huge butterfly controversy, over the business of selling live specimens for release at weddings and parties.

The cycle is beguiling: brilliant flight, and then the tattering of wings, and death. Broken wings on rock, and creek bank, and car windshield. The closer you get to butterflies, the less sentimental they seem. Less lyric opera than Greek tragedy.

Or maybe it's allegory. Butterflies are always leaving their old selves behind. They are harmless, and beautiful, all parable and possibility, wrenching and twisting and waking, finally, to a brief, spectacular flight toward something ecstatic, something closer to the sun.

Imagine it. One day you wake up and your old skin has fallen off and you have become someone, something, else, barely recognizable even to yourself. It could be. There certainly seems to be more to this butterfly thing than binoculars and field guides. Because the thing about butterflies is, once people get interested, they seem to become enraptured. Rapt.

Which is how I come to be in the middle of a meadow in the middle of the summer, last in a line of intent and sweaty people who are picking their way down the hillside and waving large white butterfly nets.

It's hot out here. Butterfly flight time is midday, and butterflying is not for the weak. From where I stand, sun-stupid and hallucinating, we're starting to look like one giant insect with wiggling, waist-high antennae.

We're somewhere outside Thurmont, Md., about an hour and a half northwest of Washington, me and about 18 members of the Washington Area Butterfly Club. Our quarry is the Baltimore checkerspot, a little dark brown butterfly with 21/2-inch

orange-and-white spotted wings that resemble the Maryland state flag. It happens to be the official state insect. It also happens to be vanishing.

"Okay, let's fan out and look out for puddles of water," says Dick Smith, the group's leader, an electrical engineer at the Applied Physics Lab at Johns Hopkins University who is also a self-taught expert on butterflies and an award-winning conservationist for work on behalf the region's fragile butterfly populations.

"The turtlehead's in the boot, down there," he says, pointing to the watery pocket at the bottom of the meadow.

Butterfly species have evolved to require one particular plant as a host for their eggs. This meadow is dotted with milkweed and spice bush, as well as purple thistle, pink daisies, cinnamon and shy fern, hay grass, clumps of sedge and pale green orchids and primrose, but the Baltimore checkerspot's one and only happens to be the turtlehead plant, a shy, wild snapdragon that deer find delectable and that needs a constant bath of water around its feet in order to grow.

We scatter like beads on a snapped string. I thrash through the tall weeds and fall in directly behind Smith, who, despite the heat, is wearing heavy bluejeans against ticks and chiggers, a long-sleeved cotton shirt and a faded cap held up by two extremely sunburned ears. I follow the ears, and we make our way downhill.

Once upon a time, the Baltimore checkerspot was common throughout the Washington area. Records from as recently as the 1930s show there were large colonies of them in Rock Creek Park, and all over Prince George's and Montgomery counties.

There are still a lot of them in other places (the Baltimore's range extends as far north as Massachusetts), but they have almost disappeared in this area, and the decline seems to be accelerating. No one is exactly sure why -- butterfly populations have considerable wax and wane under normal conditions -- but the drop in Baltimore numbers has been deemed worrying.

This matters more than it might seem, and for more than mere aesthetic or moral reasons. After bees, butterflies are the planet's most important pollinators of crops and wild plants. And more important, butterflies are bellwethers for the overall health of the environment -- the above-ground equivalent of canaries in the mine shaft.

The news so far this morning up here in Thurmont is not good. In 1997, same month, same site, club members counted at least 35 specimens. This year, the count is zero.

Swish swish, brush brush, the nets flash back and forth. It's only for show. Netting butterflies for collection has mostly gone the way of big game hunting. The nets are for flushing the butterflies out of the grass. They can't hear, but the sight of the large white nets is startling.

There are butterflies in every stage of development here -- adults on the wing, eggs no larger than a period on this page dotting leaves, comma-size caterpillars and their older siblings, smooth and striped. (Generally, butterfly caterpillars are smooth, moth caterpillars furry. Another handy rule for sorting the two: Butterflies have tiny clubs at the tips of their antennae; moths don't.)

This "meadow" is actually a long swath of power-line cut -- a wide clearing between two borders of forest where the power company has removed the trees. In the usual environmental equation, these cuts qualify as a man-made desecration of the wilderness. But they turn out to be excellent butterfly habitat -- full of weeds, wildflowers and plenty of sun, the butterfly's nonnegotiable requirements.

As we descend, water begins to ooze around our feet, flowing around the outcroppings of warm gray rock. At least a dozen species of butterfly -- painted lady, spicebush swallowtail, silver-spotted skipper, great spangled fritillary -- are putting on a talent show. Each species has a distinctive flight pattern. Clusters of males are "hilltopping," congregating at a high spot, looking for females. Others are "puddling," lighting on mud flats to suck up the salt and minerals they need to make sperm. Still others are perched on plant tops for long minutes, collecting the solar heat they need to make their wings work. (When the sun goes behind a cloud, butterflies are temporarily grounded.)

It's a hard life. Butterflies are eaten by birds, smashed by cars and, perhaps most dreadfully, preyed upon by parasitic wasps who perch on the back of a defenseless adult or caterpillar, lay eggs under the creature's skin, leaving their offspring to hatch and eat their host from within.

The nature show is dazzling, but so far bereft of Baltimore checkerspots. At the bottom of the meadow, we find out why.

"Yeah, you can see the deer have eaten the heads right off these," says Smith. So many deer have ambled here for food recently that they've worn a path in the grass. The plant tops are gone, and with them, most likely, the egg clusters that would be most of next year's Baltimore checkerspot colony.

Someone suggests -- only half joking -- that the club's next conservation campaign should be to reintroduce the mountain lion in Maryland state parks.

Actually, the club's got another plan, the brainchild and passion of club co-founder Pat Durkin. The idea is to establish new plantings of turtlehead at several sites around the Washington suburbs and hope the Baltimore checkerspots will find them. This has worked with several other butterfly species.

So far, though, the project -- now in its fourth year -- has been unlucky. The first year, someone stole the first batch of turtlehead seedlings off Durkin's back porch. The rest were planted at Kenilworth Aquatic Gardens but were eaten by deer. Ditto the second year, at Little Bennett Regional Park, in Montgomery County. The third year the plants succumbed to fungus before they could be put in the ground.

Durkin, a nature writer by trade, is a determined soul, the builder of several community butterfly gardens in trash-strewn alleys and vacant lots in her Logan Circle neighborhood. The gardens attracted two score butterfly species, as well as homeowners and street people who learned a lot about butterflies and even more about each other before the gardens were razed to make way for town houses.

Now, she's got three dozen more turtlehead seedlings ready to go. All that's needed is a place to plant them. It has to be wet. It has to be safe from hungry deer. And it has to be near Washington.

Soon enough, we're talking turtlehead in a farm kitchen in northern Montgomery County. Pat Durkin sits across the table from our host, Jay W. McRoberts, a commercial butterfly farmer and conservationist.

The two, both members of the Washington Area Butterfly Club, are having a mild disagreement at the moment -- a bit of an antenna-basher -- about the best next step to help the Baltimore checkerspot.

These are butterfly people, so there isn't a lot of shoe pounding going on or anything. Still, as I pet the cat and listen, I'm thinking that in its quiet way, the debate lays out the thorny questions that can crop up when something fragile gets popular. It reminds me of a song lyric. Not a song about butterflies, per se, but fitting, maybe. You know the one. About how you always hurt the one you love.

McRoberts, a retired orthopedic surgeon and hands-on tree farmer with the calluses to prove it, has volunteered to plant the turtlehead seedlings on his 330-acre property. He's even offered to build an eight-foot fence around the plants to protect against deer. "Whatever it takes, that's what I'll do," he says.

But he has another idea. This one's less passive. He wants to go up to Thurmont and net a couple of pregnant female Baltimore checkerspots. The idea is to bring the females back to his farm, let them lay eggs on turtlehead plants inside his flight houses, and hand-raise the caterpillars in customized Rubbermaid boxes, the way he does the 15 other species he husbands.

It's a win-win deal, McRoberts says enthusiastically. Maryland gets a new and protected stand of turtlehead, and if the colony takes root, he gets some Baltimore checkerspots to sell to eager exhibitors, including Montgomery County's own Brookside Gardens park.

Durkin, initially in favor, has checked with some naturalists and now has reservations about removing even one egg from the struggling Thurmont colony.

"Well, I don't want to do it now," she says. "Anyway, they're just at the end of their flying season. You might get larvae, but you won't get pregnant females."

"I don't particularly want adults," McRoberts says. "I'd far sooner have the larvae any day."

"Well, it's a pretty fragile population right now, you know," she tries. "We only found four adults up there this year."

All the more reason to help them, he counters.

She's been unable to reach the University of Maryland entomologist they need to talk to, she says. "I called him yesterday. He wasn't in."

"Well, maybe he's in today," McRoberts offers.

Keep in mind that 10 years ago, this scene would not have existed. Back then, butterflies were still largely the esoteric province of bug scientists and highbrow Russian novelists.

That was then. Now we have butterfly exhibits opening in city museums, amusement parks, even hospitals. There are dozens of books devoted to how to plant a butterfly garden, and enough people breeding butterflies commercially that they have their own professional association. We have butterflies as metaphor, as motif, as therapy, hobby, window to the world, midlife crisis and even career change.

Butterfly gardening and butterfly houses have their roots in 19th-century England. Much of the new burst of activity in this country dates to the mid-1980s, when '70s-era environmental concerns began to dovetail with the gardening passion of an aging population. Things really took off in the early 1990s, when a molecular biologist named Jeffrey Glassberg published a field guide that helped revolutionize and popularize the study of butterflies by showing people how to examine them without killing them.

The book -- Butterflies Through Binoculars -- was designed for those who wanted to use high-powered binoculars and close-up camera lenses instead of pins and nets. The obscure ranks of lepidopterists were joined by legions of hobbyists who called themselves "butterfliers," drawn to study butterflies out of a love for natural history.

Glassberg also founded the North American Butterfly Association, to organize these butterfliers and to create a constituency for conservation. The association has 23 chapters around the country, with 10 more in formation. That doesn't even include many active but unaffiliated groups, such as the Washington Area Butterfly Club, which convened with three members three years ago and now has more than 90.

McRoberts is both a creature and beneficiary of this development. He supplies live butterflies and chrysalises -- thousands of them each year -- to butterfly exhibits from Brookside Gardens to Hershey Park, Pa., to Chicago.

He's done this with the meticulousness of a surgeon and the zeal of a completist. He has a quarter-acre butterfly garden, four mesh-covered butterfly flight houses, and a part-time intern who spends long afternoons feeding leaf sprigs to thousands of butterfly caterpillars and using a tiny paintbrush to move them around during cage-cleaning.

His butterfly operation -- well run and the only one of its kind within 500 miles, he says proudly -- has become a field-trip destination for Montgomery County elementary school science teachers, students from the U.S. Department of Agriculture nature studies program and butterfly counters from the Washington club. It's a place where on a given day in the right season, you might see more than half of the 50 species native to Maryland.

Around the country, most scientists and conservationists agree that nearly all of this interest and activity has been good for butterflies. The more people know about butterflies, the hope is, the more likely they'll be to speak out the next time a developer wants to bulldoze a rare butterfly habitat. And the less likely they'll be to shower their yards with insecticides. And by creating a market for tropical butterflies, the butterfly exhibits help preserve habitats in less developed but butterfly-rich countries around the world.

There is one dark cloud in this clear blue sky. That is the practice called butterfly release, the business of shipping farm-bred live butterflies to people who want to release them at weddings and fund-raisers and other social occasions. McRoberts this year began selling butterflies for release; it's a sideline, he says, only about 5 percent of his business. While Glassberg's group and many entomologists are enthusiastic about butterly exhibits, they condemn the practice of release. They argue that it will weaken native butterfly populations, interfere with scientific study and spread disease. (The butterfly is the best studied of all insects, but there is still a lot that is not known. Our understanding of butterfly diseases is only just beginning.)

Even the relatively simple matter of capture and relocation of a few Baltimores is fraught with dilemmas.

Durkin and some prominent local naturalists think moving the Baltimores would be a mistake. But Dick Smith, leader of the Thurmont count, thinks it's a good idea. Most likely, some compromise will be found to satisfy everyone.

A few weeks later, in mid-August, the thinking is that some larvae can safely be taken from Thurmont down to McRoberts's farm for raising, and the resulting colony used to reestablish the population in other locations.

And soon enough the move is forced upon them. When Durkin returns to the meadow, she finds that the watery bottom has been severely degraded by all-terrain-vehicle traffic. An area the size of a basketball court, including the turtlehead bed, has been worn to bare dirt and water-filled ruts a foot deep. There have been further inroads by deer. Only one cluster of Baltimore checkerspot larvae remains. On the basis of what Durkin calls "imminent danger," it is decided to take the nascent colony back to the McRoberts farm to raise the Baltimores for next year.

And that's the seductive thing about butterflies, she says. It's not like trying to save the snow leopard, where all you can do is mail checks to some distant environmental organization, "and even then it probably won't work."

"With butterflies, you can do some planting, and you can really make a difference."

There are plenty of theories about why the world has gone wild for butterflies just lately. Butterflies are beautiful. Butterflies are harmless. Butterflies are a natural extension of the 1990s interest in gardening and native plants. No, it's more a panic reaction to the growing signs that mankind is global-warming the planet into oblivion.

All true, doubtless. But maybe what it really comes down to is Janet Bruner, a suburban mom, sitting in her Arlington living room one July morning, wiping her brow after a brief tour of her modest backyard butterfly garden. She apologizes for the weeds -- "It's really getting out of control" -- and attempts to subdue her humidity-crazed hair.

On the porch, she shows the glass tank where she's raising red admiral caterpillars. Sometimes they chew so loud you can hear them crunching from all the way inside the house. The caterpillars are a project for her kids, really, but kids are kids, and a lot of the work falls to her.

And that's okay. She remembers exactly how -- and when -- the butterfly thing hit her. It was recently, although she thinks it's connected to her childhood in Kensington, near Rock Creek Park. There weren't a lot of organized activities for kids back then -- no diving camp, no soccer team. All they had was the woods -- for building forts, and chasing butterflies.

She grew up, traded butterflies for school, and boys, and then came marriage and kids and jobs and mortgages, and all the things we acquire to make life worth living but can wind up calcifying around us and cutting us off, until we can barely remember why we wanted them.

So there was this moment. She was at a local park with the kids, and she saw a brochure for butterfly gardening. She signed up for a class called Butterflies 101. "It just knocked me out -- I didn't know there were people who went out and did these things, that you could go out and find caterpillars," she says. And she took another class, this one in a wetland park, Huntley Meadows, in south Alexandria. She remembers it very clearly. She had the baby in the stroller. She and the baby and all of these birds and fish and frogs and turtles and tadpoles, and hundreds of butterflies.

She took another class. It was as if she had stumbled, at long last, into her tribe, her long-lost tribe, the people as fascinated with the natural world as she was, who longed for a connection to it the way she did. There are people she can call in early March, she says, the one day of the year spotted salamanders will be making their mass migration down the hillsides to the ponds, and say, "Hey, you want to go look for spotted salamanders?"

And these people will say yes. And they will go and do it, go crouch in the cold rain to witness this weird wonder of nature and feel happy and grateful at having seen it, having found it amid all of life's near misses and lost connections and tangled threads.

Life can change, just like that. You can think you are lost and that everything is over, and wake up one day and be found.

That's what butterflies do, in a way, and they do it late in their lives. After four or five preparatory molts, when they've gotten about as big as your thumb, the caterpillars wrap themselves up inside the hard chrysalis, and then they literally reconstitute themselves. They melt down into some weird primordial goo and then reform as angular, wrinkly blobs that one dawn slide suddenly from the container like a letter from an envelope. They hang upside down a day or so and pump their wings full of juice, and then take off as butterflies, to mate and find nectar.

What a wild idea. That you can hunker down and think things through and change the shape of your very skin. And then you can hang there awhile, all upside-down, and take a deep breath, and fly.

Mary Battiata is a Magazine staff writer.