How is bee pollen collected?

Beekeepers put a device called the "pollen trap" over the entrance of the hive. It consists of a series of wire mesh screens that the bees crawl through to get into the hive. The pollen trap does not hurt the bees at all, but it does knock about half of the granules out of the sacks, or corbiculae, from the bees legs, where they fall into a tray that the beekeeper empties periodically. Collecting bee pollen is actually beneficial to the hive, because bees over-collect pollen.