Bees cannot distinguish red from black, Dr. von Frisch has found. This probably is the reason so few red-blossoming plants depend on these insects for distributing their pollen. Nearly all red-blossoming species depend on birds and butterflies, both of which are acutely sensitive to red. One notable exception, however, is the European poppy whose brilliant red blossoms carpet the landscape in late Spring. The German experimenter has found that these blossoms are not “red” to the bee. They possess a color which cannot be described because it cannot be experienced by the human eye. The poppy blossoms reflect a great deal of the ultraviolet light in sunshine and to this the bee eye is extremely sensitive. The color must be quite different from any of the shades at the blue end of the spectrum which are visible to man. To the bee it is probably somewhat like violet. Even the more or less degenerate human nose can be trained to discriminate some of the bee odors that apparently have so much meaning in the life of the hive. After practising for a few months Dr. N. E. McIndoo of the U. S. Department of Agriculture was able to recognize the three castes—queens, drones and workers—merely by smelling them. With more practice he was able to make even finer discriminations, as he reports: “The younger the workers the less pronounced is the odor emitted. To the human nose the odor from nurse bees and wax generators is much less pronounced than is that from old workers. Workers just emerged from the cells have a faint, sweetish odor, but lack the characteristic bee odor and workers removed from the cells just before they begin cutting their way out omit a still fainter sweetish odor. “Old queens have a strong sweetish odor, while that of queens just emerged from cells is much pronounced as is the bee odor of the workers. The majority of old drones have a faint odor while every young drone has a stronger one. It is slightly different from that of young workers and is less sweetish. “All the offspring of the same queen seem to inherit a peculiar odor from her, which becomes the family odor. Apparently each worker emits an individual odor which is different from that of any other worker. “Of all odors, that of the hive is most important. It seems to be the most fundamental factor upon which the social life of the colony depends, and upon which the social habit perhaps was acquired.”