Second half of October. Made up a stronger sugar syrup (higher sugar to water ratio) and gave hives sugar syrup on Monday Oct 17th, Friday Oct 21st, Wed Oct 26th. At first I noticed that the level of the sugar syrup dropped quickly, and they seemed to be ready for a fill-up by my next visit. But by Wed Oct 26th, the temperature had dropped - frosts overnight for the previous two nights - I noticed that the syrup had only dropped about 1/3rd of the way down since I last filled it the previous Friday. Bees aren't able to move as well when they are cold and the temperature has dropped quite a bit since last week. When the weather is cold, bees can no longer cure any of the honey they have stored in their hive, so there is no longer any point in giving them more sugar syrup when winter starts to set in. Before, in Sept and early Oct they were sucking up the stuff so quickly, it was all I could do to make enough of it. I was still in make-as-much-sugar-syrup-as-possible-and keep-feeding mode when the weather changed and got colder. Now I have all this syrup leftover in my bee-syrup watering can. Hopefully I can manage to empty it by filling their feeders in the next few days because that's a lot of sugar to throw out. Not only that, but they are also slowing down chomping their way through their pollen patties. You don't want those to still be there over the course of the winter because they won't be able to eat them, and they can get horrible and moldy.