Definitely put 1:1 sugar syrup on. They just wont go up into the feeder when it gets cold. As soon as it warms up during the day bees will go up and feed. 1:1 sugar syrup has a low freezing temperature and 2:1 even lower. I think you're using a hive top feeder so add 1 tbsp. of apple cider vinegar per gallon of sugar syrup if you want to keep the syrup from getting moldy and fuzzy(even though it doesnt harm the bees).We will have below freezing temps again next week. Should I put syrup out anyway? The farthest out forecast says 30-33 overnight lows a week out.