86 THE POPULAR SCIENCE MONTHLY. 



of honey as could be obtained in the same time from the flora of 

 richer regions where competition lessens the rewards of labor. 



It is, therefore, necessary that the insect-dependent plants of 

 colder places should have special attractions, and they do. Ob- 

 servations prove that one or more of the three qualities — color, 

 nectar, and fragrance — which attract visitors are naturally in- 

 creased in Alpine and northern plants, and it is not strange that 

 some insects have been persuaded to leave all and follow these 

 into their colder homes. 



McLeod in the Pyrenees, Delpino in Spitzbergen and Nova 

 Zembla, Muller in the Alps, and Verhoeff on the island of Nor- 

 derney, all concluded that, in correlation with a scarcity of cer- 

 tain classes of insects, the flowers are either more conspicuous, or 

 there is a noticeable increase in number of wind or self fertilized 

 forms. 



That climate alone can not account for the lack of beautiful 

 flowers in countries where flower- visitors are rare, is the more 

 evident in the comparison of the weedy flora of Tahiti with the 

 rich one of the neighboring Sandwich Islands, or with that of 

 Juan Fernandez, in both of which honey-sucking birds abound. 



Again, there is proof of the actual preference of the different 

 groups of insects and birds for particular kinds and colors of 

 flowers. 



The richest and gayest flowers of the world are those of tem- 

 perate Australia, South Africa, the south European Alps, and 

 South America. Honey-suckers abound in the first (are found 

 nowhere else in the world) ; most of the sun-birds of the world 

 are found in the second ; humming-birds are almost exclusively 

 confined to the last ; butterflies and bees characterize the third. 



Large, bright-colored, scentless flowers seem to be the favorites 

 of birds and butterflies. 



Riley says that " white moths are naturally attracted to white 

 flowers." The difference in color between flowers visited by night- 

 flying moths and by butterflies is very instructive, showing that 

 something more than absence of light has led to the general col- 

 orlessness of evening blossoms (compare the day and night- 

 flowering species of lily, etc.), many of which are fragrant, 

 keeping "their sweetness to themselves all day," to "let the 

 delicious secret out " under cover of darkness. So fragrance does 

 the work of the honey-guides which are invariably lacking in 

 evening flowers. Since many of these remain open only a short 

 time — one, two, or three nights— it is the more important that 

 they be easily found by the keen sighted and scented friends, to 

 whom fragrance is as sure a guide as color. 



But of all insects, the females of the social bees take the 

 leadership in horticulture. They are the most useful and in- 



