Bees store honey for survival during winter. Average winter colony consumes about 15 kg - 20 kg of honey. Throughout the year, it is the 70 kg of honey. Beekeeper removes bees around 20 kg - 70 kg of honey, so the bees before winter zakrmují carbohydrate solution.
You might also wondered why plants produce nectar, the answer is simple - to plant nectar has great importance because it attracts pollinators (bees, bumblebees, wasps, beetles, etc.) who in his body disperse pollen and thus pollinate.