PREFACE TO THE SECOND EDITION. 



No better indication of the activity of the students of American 

 economic entomology could be cited than the fact that a text 

 book dealing with injurious insects requires revision at rather 

 frequent intervals. The present revision is issued in the hope 

 that it may record in some measure the progress which investi- 

 gators have made since the book was first prepared. 



Since the publication of the first edition the senior author 

 has left active work in economic entomology, but he has been 

 fortunate in securing the collaboration of his former colleague, 

 who has made a thorough revision of the original text. He has 

 added several new articles and three new chapters dealing with 

 the insect pests directly affecting man and the domestic animals 

 and with the insects affecting citrus fruits. 



Other changes in the text will be found to be minor ones, 

 with the exception of the additions mentioned, and are mainly 

 for the purpose of bringing up to date the recommendations for 

 control. 



No attempt to conform to the latest usage in naming of 

 families has been made for the reason that most students using 

 this text will be more familiar with the names as used in Corn- 

 stock's Manual than with the modern usage. 



May, 1920. E. DWIGHT SANDERSON. 



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