WHAT DO BEES SEE? By Wayne Handlos
Crocus flower in visible light (l) and as seen by a bee (r). [Utah Pest News, 2012
(C) Three flowers as seen by the human eye; (D) Same under UV light [PNAS 2001]
From last month’s newsletter, we learned that the honey bee’s vision is somewhat different from ours. While both humans
and bees have three different types of light receptors, ours are most sensitive to purple, green and yellow wavelengths of light;
while the bee’s photoreceptors are most sensitive to green, purple and ultraviolet wavelengths of light. Another way to state the
difference is that we can see colors in the yellow, orange and red areas of the spectrum of light, but bees have little sensitivity to
this part of the spectrum. On the other hand, bees can detect ultraviolet (UV) wavelengths of light, which our eyes do not respond
to at all. (Our skin does respond to UV light which triggers pigment production [tanning], sun-burning, aging and various skin cancers.)
Many studies have been done on honey bees. The classical work by Karl von Frisch (The Dancing Bees, 1953), introduced us to
the communication abilities of honeybees. Utilizing various "dances" bees are able to let other bees know in which direction and how
far away a source of nectar is to be found. The scent/fragrance molecules produced by flowers are carried by the bees and let other
bees know how the flower (nectar source) smells.
Botanists and flower lovers have long been intrigued by the patterns of lines, dots and colors on flowers and assumed this had something
to do with aiding bees in finding nectar within a flower. Once scientists learned more about bees’ sight and their UV light sensing abilities,
it was just a matter of time before flowers were studied and photographed under UV light to see just how bees would perceive these patterns.
And then even more floral complexity was revealed which we humans had never expected. Flowers were seen to have bulls-eye patterns
and lines directing bees to the part of the flower where nectar could be found.
Check out these websites for more information and pictures. Please visit these sites that have the most spectacular images of flowers. They are copyrighted so we cannot show them here.
Next month we will see how flowers of the Geraniaceae might appear to bees.