No. 539] 



THE BEHAVIOR OF BEES 



681 



45, or 37.5 per cent., were by honey bees ; 6, or 5.0 per cent., 

 were by Elis plumipes; 16, or 13.3 per cent., were by 

 bumble bees ; 8, or 6.6 per cent., were by various small 

 unidentified bees. A single entrance was made by a 

 large butterfly. 



Although it seems clear that the corolla of cotton 

 blossoms invites the first approach of the bees through 

 their visual sense, it is not so easy to determine the rela- 

 tive importance of the sense of sight and smell involved 

 m their nearer inspections. Just why do so few bees 

 decide to enter? In their careful inspection of a single 

 petal or a suspicious blossom is the sense of sight alone 

 involved? Except for a single Elis plumipes. no bee has 

 ever alighted upon detached cotton petals, although 

 these have served to attract attention quite as often as 

 the control blossoms. It is not unusual, however, for 

 the bees to inspect these structures very intently, almost 

 touching the surface in their movements over them. 

 The bees have just as persistently refused to enter all 

 artificial blossoms or blossoms mutilated by removing 

 a part or all of the petals. In experiment 6 a bee was 

 completely deceived by the unreal structure at (c) made 

 to simulate an expanding bud by the use of actual cot- 

 ton petals and portions of a cotton leaf. In this instance 

 the bee inspected and finally squeezed itself down be- 

 tween the petals. Unless the fresh petals themselves 

 possess a characteristic odor, odors such as might 

 emanate from a normal blossom were entirely lacking 

 and, therefore, could not have induced the bee to enter. 

 Plateau concludes that visual conspicuousness by means 

 of bright colors is of no advantage whatever to blossoms 

 so far as insect visitors are concerned. He claims that 

 if in nature all blossoms were green like the surround- 

 ing foliage, they would be just as readily discovered by 

 bees and other insects in virtue of their odor. The 

 enter's experiments in the field indicate that conspicu- 

 ousness in virtue of their position and yellow coloration 

 is a very important factor in leading bees and other in- 

 sects to perceive cotton blossoms. 



