THE SECRET OF FLOWERS 



found to belong to a single species of fly {Empis rufescens). 

 Further observations show that in this locality this fly is 

 probably the only guest. A burly bumblebee flew over the 

 flowers without paying any attention to them. 



Among aquatic plants living in fresh-water rivers is the 

 bladderwort {Utricularia vulgaris). The whole plant is sub- 

 merged; but at blooming-time a flower-stalk is thrust out of 

 the water, which produces deeply two-lipped, bright yellow 

 flowers. (Fig. 3.) I certainly expected to find it a favorite 

 of bees. But after repeated observations I have collected on 

 the flowers in Maine only the long-tongued syrphid fly {Helo- 

 philus conostomus) . There is no way in which we can so 

 easily learn the defects of flowers as to watch the behavior of 

 insects upon them. No human eye can discover them so 

 quickly. In a word, if we would fully understand the bright- 

 hued floral edifices which so freely adorn the outdoor world we 

 must study the modus operandi of their architects and builders. 



19 



