Bees getting ready for winter.
The hives are now heavily propolized (sealed with propolis, natures own sealant) to keep cold winter winds out of the gaps of the hives. Propolis is made from plant parts and bee saliva and pasted over every gap and crack and crevice. There are over 60lbs of honey now stored in each hive. This is the amount needed to get through an average mid-Atlantic winter. (They replenished that which I took during extraction in June, when I fed them sugar water from August through September.) The bees are now clustering in each hive around their respective queen, once the temperature falls below 45F. We hope they cluster under the honey stores so as they can move up in the hive through the winter where there is always honey readily available for to them to eat. It supplies the energy for them to vibrate and keep the hive warm at around 90F all winter long. The queen remains warmest in the center of the cluster. On warmer winter days (above 58F), they will break cluster and take cleansing flights (as pictured above), coming out of the hives to get rid of metabolites that have built up inside their bodies. Metabolism is much slower in winter bees and at cooler temperatures, so they do not become poisoned by their own metabolites building up; but they do need to take these flights to cleanse themselves, or this might ultimately occur. (Winter bees have a different longevity and metabolism from summer bees, allowing for this to work.)