CONTENTS. 



Page. 



Introduction 11 



Earliest observations on the insect in America 13 



Early records in Europe 16 



Known distribution in the Eastern Hemisphere 16 



Known distribution in the Western Hemisphere 18 



The outbreak of 1890 19 



The outbreak of 1901 21 



The outbreak of 1903 21 



The outbreak of 1907 27 



Losses from depredations in 1907 39 



The situation in 1911 40 



Food plants 41 



Character of attack 44 



Viviparous development 44 



In the South : 44 



In the North 49 



Rearing methods 51 



Stem mothers 58 



Description of the different instars 58 



Description of the summer forms 59 



Molting 61 



Number of molts 61 



Birth of young 63 



Number of generations per year 63 



Age at which females begin reproducing 70 



Reproductive period 71 



Longevity r 72 



Fecundity of viviparous female 73 



Fecundity of wingless vs. winged females 75 



Average number of young produced daily 76 



Sexual forms 76 



Descriptions 77 



Molting 78 



Oviparous development 78 



Age at which females begin oviposition 78 



Place of oviposition 79 



Period of oviposition 79 



Length of life of the sexes 80 



Fecundity of oviparous forms 81 



Aberrant individuals 81 



Influence of winds on diffusion 81 



Influence of temperature on diffusion 88 



5 



