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 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 
