Dr Adam Hart meets the migratory bee keepers of America as they travel to the annual Almond bloom in California, the largest single pollination event on Earth. Each year, from the end of February to early March, a thousand square miles of almond orchards bloom in unison, turning much of California's Central Valley white. 75 per cent of the world's almonds come from these orchards and to ensure successful pollination, farmers need bees - a lot of bees. Around 1.5 million hives, over 30 billion bees, swarm over the bloom for three weeks a year, before they're packed up and driven on to pastures new, be it Washington Apples, Maine Cranberries or Florida Citrus. Welcome to the extraordinary world of migratory beekeeping. This isn't about the honey, it's about the money. Beset by viral diseases, pesticides, starvation and the ever-present threat of colony collapse disorder or CCD, even a vigilant bee-keeper can expect 20-30 per cent of their hives to die-off in any given year. So why bother? "This is what we do" says John Miller, "I was born to keep bees in a box". Miller's great-grandfather invented migratory beekeeping, which thanks to increasing demands from farmers, can earn even small to medium-sized keepers, millions of dollars just from almonds alone.

Producer: Rami Tzabar