Bees can only take down and evaporate liquid syrup while it's
warm enough to fly and fan. Below roughly 8°C uptake collapses
to near zero, which is exactly why autumn feeding has a hard
calendar deadline — once night temperatures drop for good,
switch to solid fondant instead.
temp_factor = clamp((T − 8) / 10, 0, 1)
conc_factor = 0.7 + 0.3 × (ratio − 1) // heavy syrup needs less evaporation effort
intake(L/day) = feeder_supply × temp_factor × conc_factor
stores_kg += intake × sugar_fraction × Δdays
capped_kg += (stores_kg − capped_kg) × 0.35 × temp_factor × Δdays
- Outside temperature — drives
temp_factor; below ~8°C the colony stops processing syrup efficiently.
- Syrup ratio — heavy syrup (2:1 sugar:water) is closer to ripe honey and needs less evaporation, so it's taken down and capped faster than light (1:1) syrup.
- Feeder supply — how much syrup is offered per day; the ceiling on how fast stores can grow.
- Entrance reduced — a full, actively-fed hive attracts robber bees from weaker colonies; reducing the entrance cuts robbing pressure and the stores it steals.
UK colonies typically need around 18–20 kg of capped stores
to reach spring — hefting the hive by hand is the traditional
practical check, since a light hive is the clearest sign more
feed is needed before it's too late.