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 tig culture possible 



in California. (After Westwood.) 



B, plum blossom; 0, ovary; p, petal; se, sepal; sta, stamen; si, 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, 

 and man indirectly 

 with larger and better 

 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 



Fig. 45. — Predaceous insects. 

 A, tiger beetle ; B, European ground beetle im- 

 ported to prey upon the gypsy and brown-tail 

 moths. (After Bruner and Howard.) 



