PREFACE. Vll 



To the authorities of Cornell University the authors of 

 this book are under deep obligation for aid and encourage- 

 ment. The preparation of the work would not have been 

 possible but for the liberal grants which they have made for 

 the purchase of specimens and books. 



JOHN HENRY COMSTOCK. 



ENTOMOLOGICAL LABORATORY, 



CORNELL UNIVERSITY, 



December, 1894. 



