BENEFICIAL INSECTS 



69 



is formed than when the pollen of a flower fertilizes the ovules 

 of the same flower (self-pollination). Many plants are cross- 



FIG. 44. A, fig insect whose introduction has made Smyrna fig culture possible 



in California. (After Westwood.) 



B, plum blossom ; o, ovary ; p, petal ; se, sepal ; sla, stamen ; st, stigma ; 

 s, style. (After Bailey.) 



pollinated only by insects and would not produce good seed if 



insects did not fly from one flower to another and thus distribute 



the pollen grains that 



become attached to 



their bodies. In some 



cases the insects seem 



to realize what they 



are doing, since they 



deliberately transfer 



pollen from the sta- 



men to the pistil. The 



plants are benefited 



directly by the pro- 



duction of better seed, FIG ^ _ predaceous insects 



and man indirectly A) tiger beetle . B European ground beetle im- 



ported to prey upon the gypsy and brown-tail 



moths. (After Bruner and Howard.) 



with larger and better 



A , 



crops. In return, the 



insects take nectar from the flowers as their transportation 



charges. 



The dependence of plants upon insects is well illustrated by 

 the Smyrna fig. Prior to the year 1900 this fig could not be 



