Sugar syrup is usually made in two different ratios depending on the time of the year. Light syrup or spring syrup is 1 part sugar to 1 part water by either weight or volume. Heavy syrup or fall syrup is made from 2 parts sugar to one part water.
The rationale behind these sugar syrup ratios is that light syrup is similar to nectar. The availability of nectar stimulates the production of brood in the spring, and light syrup tends to do the same thing. With a ready supply of nectar or light syrup, the workers will build comb and the queen will lay eggs. Some people advocate the use of 1 part sugar to 2 parts water to stimulate brood rearing, although this isn’t as common as it used to be.
Fall syrup resembles honey and bees tend to store it for winter. It is used in the fall if the beekeeper feels there is not enough honey stored in the hive to make it through the winter. One gallon of heavy syrup (2:1) may increase colony reserves by about 7 pounds.
Plain white sugar is best for bees
It is important to use just plain white granulated sugar, not brown sugar, molasses, sorghum, or fruit juices as these all have impurities that can cause dysentery in bees. Confectioner’s sugar has corn starch in it, which is also not good. Some older recipes recommend the use of cream of tartar (tartaric acid) to keep fall syrup from crystallizing, but this practice has been largely abandoned because it, too, may be bad for bees. Bee dysentery is not a disease caused by a pathogen but a condition caused by poor quality food. It appears as spots of feces around the hive entrance, or inside the hive, and is easily confused with Nosema, which is caused by a pathogen.
The source of the plain white sugar doesn’t really matter. Refined table sugar (sucrose) is a disaccharide derived from glucose and fructose, and has the molecular formula C12H22O11. It is the same whether it came from cane or beets.
In the spring, discontinue syrup when the hive is strong and the nectar is flowing, when the bees lose interest in syrup, or when you install a honey super. In the fall when the weather gets cold enough, the bees will simply stop taking the syrup. When that happens, remove the remaining syrup to prevent fermentation or moisture build-up in the hive.