Without the perception of red, flowers of this shade can blend together with more visible background colors, making it a bit more difficult to discern red flowers. Bees actually take longer to find red flowers. Because the red color is absent, bees rely on the intensity of their green receptors to detect these shades.
Still, there are plenty of red flowers that attract bees – Monarda, for instance, is commonly known as “bee balm” and sprouts large nectar-filled red blossoms that attract bees throughout the spring and summer. Specific flowers have evolved to attract bees with plentiful nectar stores, in return for a cross transfer of pollen.