300 EXPERIMENTS WITH PLANTS 



blooming flowers are proverbially sweet-scented, and 

 doubtless depend principally on the odor to attract the 

 moths which visit them, although the color may be of 

 some assistance also (such flowers are usually white or 

 light in color). The question therefore arises, Does not 

 color, after all, play a subordinate part in attracting in- 

 sects? especially as it has been shown, by experiment, 

 that bees and wasps cannot clearly distinguish objects 

 more than two feet away (butterflies and moths see but 

 a few feet) ; while they can scent honey for long dis- 

 tances. In the case of flowers which produce nectar 

 (or honey), therefore, color would seem to be not so 

 important. 



A very interesting series of experiments can readily 

 be made by any one who has sufficient leisure to watch 

 the visits of the insects for a time. Choosing a plant 

 which is freely visited, note the number of insect visits 

 in an hour: remove the petals from a part of the 

 flowers, and cover the remainder with screens made of 

 green leaves (a single large leaf may be folded so as to 

 form a sort of cap for the flower) . Endeavor, by noting 

 the number of insect visits in an hour, to determine 

 whether the loss or concealment of the color has an 

 appreciable effect. 



The flowers of many plants are not visited by insects 

 (e. g., Grains and Grasses, Oaks, Hazels, Poplars, 

 etc. ; Pines and other Conifers, Palms, Hops, Nettles, 

 etc.); in these cases, the pollen is transported by the 



