Fat Bees are the ones that get the queen through winter.
The time is here to make sure the mite levels are below the treatment threshold by August 15. It's critical for the successful rearing of Fat Bees which are required for overwintering success.
Brood rearing stops in the fall. The emerging worker bees have no brood to feed so they store it for winter. Thus becoming 'Fat Bees'.
Be sure to check your hives for mites and treat if necessary. It takes time and effort, but makes the difference between being a beekeeper and a boxkeeper.
Enjoy your bees and the honey they produce.
Gerard