Bees have two big compound eyes made of numerous small lenses. They are located on the upper part of their head. Bees also have three smaller eyes called ocelli, which have a simpler functioning that resembles the way photocells work.
Even though they cannot see all of the details of an object, bees’ set of eyes enables them to see their surroundings while flying. Their viewing angle is almost 360°. In addition, the range of colours these small workers can perceive is slightly different from ours. They cannot really see all the shades on the red end of the colour spectrum but can see many more shades on the ultraviolet end. That portion of the colour spectrum is invisible to the human eye.
Thanks to the way their eyes work, bees can fly fast and avoid all kinds of obstacles they meet on their way. Neither natural obstacles – such as tree branches, leaves or even predators – nor obstacles put there by us humans – walls, fences, sunshades – will stop them. Windows are the only exception. Bees cannot see glass.
Simply put, bees do not pay attention to details. The speed and angle to which subsequent images change as they fly is what really matters to them. This is why shape and colour take a backseat in bees’ world.
XXth century Austrian biologist Karl Von Frisch said many interesting things on this matter. In 1950 he published the results of his research and experiments in a book called Bees: Their Vision, Chemical Senses, and Language. This book has an entire chapter dedicated to the issue of the way bees perceive colour (The Color Sense of Bees).
First of all, Von Frisch gave an initial clue regarding bees’ sight. He noted how bees are attracted by strong colours. He also said that flowers of a scarlet red colour are more difficult to find in Europe, but they are most easily found in Africa and America. Then he said that after a series of experiments he realised bees cannot see the red colour, but they can well see ultraviolet. This explains why bees prefer poppies. To the human eye, poppies are red, whereas bees can see its strong ultraviolet shades too. There is more. Poppies are also a great source of pollen.