Bees are by far the most effective pollinators because they feed only on flowers. Flowers attract and reward bees for their pollination service. Bees gather two kinds of foods from flowers: sugar-rich nectar to fuel their flight and protein-rich pollen, or bee bread, to feed their young brood. There are over 4,000 species of bees native to North America. They nest underground, in twigs, debris, dead trees or managed hives.