Nectar is the second resource which bees require for survival. Nectar is the essential carbohydrate source which bees use to fuel all their activity and reproduction. Nectar which is later transformed into honey is what the bees use to survive the long winter months and periods of dearth.
In early spring the bee colonies are coming out of a period of dormancy and are looking for new sources of pollen and nectar. Early spring is a risky time for bee colonies as they are increasing their daily caloric requirements but do not yet have a nectar flow to harvest. Dandelions are the first sign of a nectar flow in the Denver area and bees are quick to harvest the resource.
Maybe we should think twice before removing this valuable source of nectar. We should most certainly stop using herbicides to destroy these nectar sources.