I seem to remember that bees distinguish blue, green, and yellow the best. Is that correct? Been too many years since I read ABC and XYZ, and I can't recall clearly.
From ABC XYZ of Bee culture:
"The vision of the bees begins with the wave length of light near the orange-red end and continues through the ultra-violet and of the spectrum. The bee has only limited visual ability to see the color red. We are limited somewhat in to the same extent by not being able to see ultra0violet. The human eye can perceive many more distinctive colors in the color spectrum while the bee apparently sees only four; yellow, blue-green, blue and ultraviolet. The color vision of the bee has a distinct relationship to the colors of flowers which benefit from bee pollination."