THE LANGUAGE OF BEES — VON FRISCH 425 



red-blind. That is very interesting. We understand why scarlet red 

 bee-blossoms are so rarely found. There are very many red flowers in 

 America, for instance, but only in bird-blossoms. Birds' eyes are very 

 sensitive to red. In Europe there are some plants with red flowers, 

 but their pollination is — with few exceptions — effected by certain 

 butterflies. These butterflies are the only insects which are not red- 

 blind. There is an exception to the rule — the poppy, the flowers of 

 which are visited by bees although they are scarlet red. But these 

 flowers reflect many ultraviolet rays. Bees are able to perceive ultra- 

 violet rays. Ultraviolet is a special color for them, distinguishable 

 from blue and all other colors. It is evident that the colors of flowers 

 have been developed as an adaptation to the color-sense of their 

 visitors. 



One more thing is of interest to biologists. We make the follow- 

 ing experiment. We train bees to blue, and then we put all the 

 different-colored cardboards on the table. The bees seek the blue 

 color, but are unable to find it with certainty; they confuse it with 

 violet and purple. Bees trained to yellow confuse the yellow with 

 orange and green. It is important to notice that they cannot dis- 

 tinguish as many color shades as we can. 



Bees restrict their visits to certain flowers. A given individual on 

 its trip always visits definite species of flowers. That is of advantage 

 for the bees, which on all flowers of the same land meet with the same 

 mechanism of blossom and save time through being acquainted with it; 

 it is also of advantage for flowers, for their pollination depends on bees 

 coming from other flowers of the same species. If the bees specialize 

 in certain flowers, they must be able to distinguish the different kinds 

 of flowers. Biologists formerly thought that it was the difference of 

 color shade which enabled bees to distinguish them. Now we hear 

 that bees cannot distinguish so many different shades of color as we 

 can. They must, therefore, have other means of distinguishing the 

 different kinds of flowers. It might possibly be the scent of flowers. 

 Such considerations led me to my work about the sense of smell in bees 



The result was that we found that the scent of flowers is the most 

 important factor that enables bees to recognize the different flowers. 

 We can train bees to scent just as we trained them to color. On a 

 table we place some cardboard boxes, each of which can be opened from 

 above. There is a hole in the front of the box. In only one of the 

 cardboard boxes is there a feeding-glass, and into the same box we drop 

 a little essential oil. The other boxes are without scent and without 

 food. We change the position of the food box frequently in order to 

 avoid a training to place. The scent guides the bees to the food. 

 After some hours we put away all the boxes soiled by the visiting bees, 

 and make a new arrangement with boxes not yet touched by bees. In 

 one of them, we drop a little of the scent we have adopted for training 



