CHAPTER XIV 



FLOWERS AND INSECTS 



144. Pollination. Among Gymnosperms the pollen is 

 transferred by the wind, and this is true also of many 

 Angiosperms. But the prevailing method of pollination 

 among Angiosperms is the use of insects as the agents of 

 transfer. This mutually helpful relation between flowers 

 and insects is a very remarkable one, and in some cases 

 it has become so intimate that they cannot exist without 

 each other. Flowers are modified in many ways in rela- 

 tion to insect visits, and insects are variously adapted to 

 flowers. 



The pollen may be transferred to the stigma of its own 

 flower (self-pollination), or to the stigma of some other 

 flower of the same kind (cross-pollination). In the latter 

 case the two flowers concerned may be upon the same 

 plant or upon different plants, which may be quite distant 

 from one another. Since flowers are very commonly ar- 

 ranged to secure cross-pollination, it must be more advan- 

 tageous in general than self-pollination. 



The advantage of this relation to the insect is to secure 

 food. This the flower provides in the form of .either nectar 

 or pollen; and insects visiting flowers may be grouped as 

 nectar-feeders, represented by moths and butterflies, and 

 pollen-feeders, represented by the numerous bees and wasps. 

 The presence of these supplies of food in the flower is made 

 known to the insect by the display of color, by odor, or by 

 form. It should be said that the attraction of insects to 

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