PREFACE Vll 



piled from his own writings, although it has been found 

 necessary to draw also from the works of others, and is based 

 on an experience of about ten years with the subject with 

 which it deals. The illustrations are in large part the same, or 

 adaptations of, figures previously used in the Bureau of En- 

 tomology, United States Department of Agriculture, and are so 

 credited. 



F. H. Chittenden. 

 United States Deportment of Agriculture, 

 Sept en bcr, IQOJ. 



