Autumn feeding tops up a colony's winter stores before the last warm days disappear. The sugar-to-water ratio you mix isn't just a recipe detail — a thick 2:1 syrup (2kg sugar : 1L water) behaves like concentrated nectar that bees can invert and cap quickly with little evaporation effort, signalling "store this for winter." A thinner 1:1 syrup behaves more like spring nectar flow, which tends to stimulate brood-rearing and comb-building rather than efficient long-term storage — useful early in the season, less useful once the days are shortening.
UK guidance generally favours 2:1 syrup for autumn because it mimics ripe nectar and needs minimal further evaporation before capping — important once cool, damp autumn air makes it harder for bees to drive off excess moisture and risk of fermentation rises in under-ripened stores.
Mix sugar-to-water ratio, feed type, temperature and feed rate to watch a 3D hive comb fill and cap syrup into winter stores at different speeds and moisture levels.
Thicker 2:1+ syrup needs less water driven off before a cell can be capped, so it converts to sealed stores faster; thin 1:1 syrup behaves more like a spring nectar flow. Fondant sidesteps evaporation entirely but isn't stored in comb.
Set the sugar:water ratio, pick syrup or fondant, adjust ambient temperature and feed rate, then watch the comb cells fill and cap while bees shuttle feed from the feeder. Reset the comb to try another combination.
Below roughly 10°C bees cluster tightly and barely move syrup down from a feeder — which is exactly why UK guidance pushes autumn feeding to be finished while afternoons are still reliably mild.