Honey is used by bees as a food source, but honey bees are the only bees to naturally make an excess of honey.
Honey bees make an excess of honey because honey is stored in the hive to be used when forage is unavailable or the weather is poor meaning flight time for the bees to gather more honey and pollen is reduced.
Honey bees store an excess of honey through winter because unlike other bee species. In other species only the queen bee survives winter, whereas an entire colony of honey bees will live through winter forming a cluster to stay warm. This means energy is being used up to keep warm and there could be as many as 20,000 bees mouths to feed, thus a store of honey is vital.