By the time John Miller realized just how many of his bees were dying, the almonds were in bloom and there was nothing to be done. It was February 2005, and the hives should have been singing with activity, plump brown honeybees working doggedly to carry pollen from blossom to blossom. Instead they were wandering in drunken circles at the base of the hive doors, wingless, desiccated, sluggish, blasé. Miller is accustomed to death on a large scale. "The insect kingdom enjoys little cell repair," he will often remind you. Even when things are going well, a hive can lose 1,000 bees a day. But the extent of his losses that winter defied even his insect-borne realism. In a matter of weeks, Miller lost almost half of his 13,000 hives — around 300 million bees.

When it happened, Miller was in California's Central Valley, where each February, when the almond trees burst into extravagant pink-and-white bloom, hundreds of beekeepers descend with billions of bees. More than 580,000 acres of almonds flower simultaneously there, and wild pollinators such as bumblebees, beetles, bats and wasps simply cannot transport enough pollen from tree to tree. Instead, almond ranchers depend on traveling beekeepers who, like retirees in Winnebagos, winter in warm places such as California and Florida, and head north to the Dakotas in the summer, where fields of alfalfa and clover produce the most coveted honey.

This annual bee migration isn't just a curiosity; it's the glue that holds much of modern agriculture together. Without the bees' pollination services, California's almond trees — the state's top export crop — would produce 40 pounds of almonds per acre; with the bees, they can generate 2,400 pounds. Honeybees provide the same service for more than 100 other crops, from lettuce to cranberries to oranges to canola, up and down the West Coast.

Miller likes to call the annual pilgrimage of the beekeepers the "native migrant tour," and he likes to call himself the tour's "padrone." He has thinning brown hair and an eternally bemused expression, and he never stands still. He is an observant but rebellious Mormon, and he doesn't look the part of the flannel-and-rubbers-clad beekeeper: His usual uniform includes surf shorts, a baseball cap, running shoes and a race T-shirt. (He has run 25 marathons.) Miller, who is 52, is not the biggest beekeeper in the United States, nor is he the most politically connected — South Dakota's Richard Adee, with his 70,000 hives, wins that distinction.

But Miller does, like the gentle, dark Carniolan bees he tends, have impeccable breeding. His apian pedigree dates back to 1894, when his great-grandfather, a Mormon farmer named Nephi Ephraim Miller, traded a few bushels of oats for seven boxes of bees. Nephi found he had a talent for beekeeping, and in 1907, he traveled from Utah to California to learn more efficient ways to process his swelling supplies of beeswax. While there, he noticed that California bees gathered nectar long after those in Utah had huddled in for winter. It occurred to him that if he shipped his bees somewhere warm in the cold months, he might halve his winter losses and double his honey production. The following winter, the Miller patriarch took to the rails with his apian cargo, following the blossoms from northern Utah to San Bernardino County. Bees have been on the road ever since.

The beekeeping industry tends to progress at a glacial pace — Miller often calls his fellow beekeepers "knuckle-dragging Neanderthals" who "don't play well together and with society in general," stubborn agrarian throwbacks whose business practices run toward the medieval — but there have been a few truly revolutionary advances in the technology and methods of beekeeping. The 1852 Langstroth hive, with its multiple, removable, systematically spaced frames, allowed beekeepers to inspect, move, split and take honey from their hives without destroying the honeycombs or killing thousands of bees in the process. This innovation paved the way for migratory beekeeping, which permitted the harvest of previously inconceivable amounts of honey. Nephi Miller was the first to enlist rail cars for long-distance transport, and in only a few years he produced the first million-pound crop of honey, brought beekeeping into the industrial age and inspired generations of beekeepers to follow suit. He was, in short, the Henry Ford of the apiaries.

Today, some elements of a commercial beekeeper's life remain the same. John Miller's bees ply some of the same fields that hosted his great-grandfather's hives. He sells his honey on a handshake to the same processors his grandfather used and competes with the sons of the same men his father vied against. He spends 300 days a year with his bees and gets stung almost every day, as many as 50 times on a bad day. Just the same, he counts bees among his most reliable companions. "A honeybee only has a 900,000-neuron brain, so if I conduct myself within the framework of the honeybees' limited understanding, they're fine," he said. "I understand bees. I don't understand people very well."

Recently, however, even the simple task of understanding bees has become more difficult. Like much of modern agriculture, beekeeping has changed. Where Nephi used trains and telegraphs to conduct his business, John Miller's tools of the trade are semi-trucks and contracts and spreadsheets and amortization schedules. Where Nephi made his income from honey, most beekeepers now derive all of their profit from pollination fees. Nor could Nephi expect the kind of nationwide, devastating losses that John Miller and his colleagues experienced during the almond bloom of 2005. Thirty years ago, there were nearly 4 million bee colonies in the U.S. Today, fewer than 2.5 million remain, thanks to a reddish-brown parasite so tiny it could stand on the head of a pin, and to a malady so new no one is sure of its origin.