CONTENTS. 



Page. 



Introduction 1 23 



The corn root-aphis ( Aphis maidi-radids Forbes) 123 



General account 123 



• Food plants 124 



Life history 124 



Descri lotions 1 34 



Bibliography 137 



The corn leaf-aphis ( . ip}us maidis Fitch ) 144 



General account 144 



Food plants 145 



Life history 146 



Descriptions 149 



Bibliography 151 



The sorghum aphis ( Sipha [ Chaitophorus'] Jlara Forbes ) 156 



Life history 156 



Descriptions _ 163 



Bibliography 167 



ILLUSTRATIONS 



Page. 

 Fig. 31. Periods and succession of generations in Aphis maidi-radids, 1906 127 



32. Periods and succession of generations in Aphis maidi-radlcis, 1906 127 



33. Periods and succession of generations in Aphis maidis, 1906 147 



34. Periods and succession of generations in Sipha flava, 1907 . - 158 



