218 ENTOMOLOGY. 



not bear seeds did not insects fertilize them. Insects are 

 in the first place attracted to flowers by their sweet scent 

 and bright colors, and it is claimed that the lines and 

 circles on the corolla of certain flowers guide them to the 

 nectary; though we do not see why the scent is not in the 

 main sufficient for this purpose. According to Sir John 

 Lubbock, " The visits of insects are of great importance to 

 plants in transferring the pollen from the stamens to the 

 pistil. In many plants the stamens and pistil are situated 

 in separate flowers: and even in those cases where they are 

 contained in the same flower, self-fertilization is often ren- 

 dered difficult or impossible; sometimes by the relative 

 position of the stamens and pistil, sometimes by their not 

 coming to maturity at the same time. Under these cir- 

 cumstances the transference of the pollen from the stamens 

 to the pistil is effected in various ways. In some species 

 the pollen is carried by the action of the wind; in some few 

 cases, by birds; but in the majority, this important object 

 is secured by the visits of insects, and the whole organiza- 

 tion of such flowers is adapted to this purpose." (1. c. 2.) 



Hermann Midler believed that the peculiarities which dis- 

 tinguish bees and most Lepidoptera, i.e., their mouth-parts 

 and, in the case of bees, their legs, have been gradually pro- 

 duced in past ages by their visits to flowers. 



Insects also are useful as primers, checking the too-rapid 

 growth of leaves and shoots, the result being the formation 

 of a greater amount of seeds or fruit. Unfortunately this 

 process in most cases exceeds healthy limits, and the plant, 

 being almost wholly defoliated, is weakened or killed. 



Parasitic Insects {Ichneumons and Tachina 3 ). — While 

 insectivorous birds accomplish much towards reducing the 



flowers: —that, if insects have been in many cases modified and 

 adapted with a view to obtain honey and pollen from flowers, 

 flowers in their turn owe their scent and color, their honey, and even 

 their distinctive forms, to the action of insects. There has thus been 

 an interaction of insects upon flowers, and of flowers upon insects, 

 resulting in the gradual modification of both." (Lubbock's " British 

 Wild Flowers considered in relation to Insects.") 



