ELEMENTARY STUDIES IN INSECT LIFE 



CHAPTEK VII 



THE MUTUAL RELATIONS OF PLANTS AND INSECTS 



"Insects have been inhabitants of land plants since their 

 origin in early Paleozoic ages, and the mutual relations of 

 plants and insects have ever been intimate." Cope. 



Plants and insects illustrate interdependences. In- 

 sects rely upon plants for nourishment; plants depend 

 upon insects for proper maturation of seed. Some in- 

 sects are injurious to certain forms of plant life. Such 

 feed upon the foliage, or live within the body of the 

 plant. Some insects seek their food within the nectaries 

 of flowering plants, and in so doing advance the 

 welfare of the plant. To this latter class we will con- 

 fine our study. 



Near the close of the eighteenth century Sprengel 

 first pointed out the useful purposes of colors, scents and 

 singular forms of flowers. He brought forth the facts 

 that nectar-producing plants have the nectar so situated 

 as to be protected from rain, yet easily accessible to in- 

 sects. He concluded "that the nectar of these flowers 

 is secreted for the sake of insects, and is protected from 

 rain in order that the insects may get it pure and un- 

 spoiled." His first observations, then, were that plants 

 exist for the benefit of insects. Later, however, he 

 made additional discoveries, which led him to believe 

 that many flowers are absolutely incapable of being fer- 

 tilized without the aid of insects, and therefore the secre- 

 tion of nectar and its protection from rain by the plant, 



