The average pollen grain is 25 microns wide, much smaller than the smallest filter a non-commercial beekeeper will have. Filters designed for straining honey for hobby beekeepers come in three sizes, 200 microns, 400 microns and 600 microns. These numbers represent the size of the tiny holes in each filter.
During January and February, southern honeybees work the trees over to collect pollen for the next generation of bees. They work proficiently, flying from tree to tree, gathering what they need. Some bees aren't as profecient as others... Check out this slow-motion video of our backyard hives to see it for yourself.