Foraging bees comb pollen from anthers into moistened pellets packed onto their hind-leg "corbiculae" (pollen baskets). Beekeepers can intercept a share of these loads with a pollen trap — a mesh screen at the hive entrance that scrapes some pellets off returning foragers into a collecting tray below, while letting the rest of each bee's pollen through to feed the colony.
Well-designed pollen traps typically intercept 20–60% of incoming loads without harming the colony, since foragers simply make more trips to compensate. Frozen pollen keeps its protein and vitamin content far longer than pollen left at room temperature, which is why serious pollen banks live in a freezer, not a cupboard.
Foraging bees load pollen onto their hind legs at a meadow of flowers, fly it back through a pollen trap at the hive entrance, and a share of each load is knocked into a tray, packed into jars, and aged on a pollen-bank shelf.
A pollen trap intercepts only part of what returning foragers carry; the rest still feeds the colony. Banked pollen is a perishable stock whose freshness decays at a rate set by how it's stored, and a dearth period draws the bank back down.
Set the trap efficiency and forager count to change how fast pollen accumulates, choose a storage method to see how quickly jars dull with age, speed up simulated time, and toggle a dearth period to watch the bank feed the colony.
Freezing pollen at -18°C preserves its protein and vitamin content far longer than storing it at room temperature, which is why a serious pollen bank lives in a chest freezer, not a kitchen cupboard.