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PREFACE TO ORIGINAL EDITION 



For many years the most pressing demand of teachers and learners in 

 entomology in this country has been for a handbook by means of which 

 the names and relative affinities of insects may be determined in some 

 such way as plants are classified by the aid of the well-known manuals 

 of botany. But, as the science of entomology is still in its infancy, the 

 preparation of such a handbook has been impossible. Excellent treatises 

 on particular groups of insects have been published; but no general work 

 including analytical keys to all the orders and families has appeared. It 

 is to meet this need that this work has been prepared. 



The reader must not expect, however, to find that degree of complete- 

 ness in this work which exists in the manuals of flowering plants. The 

 number of species of insects is so great that a work including adequate 

 descriptions of all those occurring in our fauna would rival in size one of 

 the larger encyclopaedias. It is obvious that such a work is not what is 

 needed by the teachers and students in our schools, even if it were pos- 

 sible to prepare it. An elementary work on systematic entomology will 

 always of necessity be restricted to a discussion of the characteristics of 

 the orders and families, and descriptions of a few species as illustrations. 

 Complete synopses of species will be appropriate only in works treating of 

 limited groups. It is believed, therefore, that it would not be wise to 

 materially change the scope of the present work even if it were possible 

 to describe all of our species. 



Although much pains has been taken to render easy the classification 

 of specimens, an effort has been made to give the mere determination of 

 the names of insects a very subordinate place. The groups of insects 

 have been fully characterized, so that their relative affinities may be 

 learned; and much space has been given to accounts of the habits and 

 transformations of the forms described. As the needs of agricultural 

 students have been kept constantly in view, those species that are of 

 economic importance have been described as fully as practicable, and 

 particular attention has been given to descriptions of the methods of 

 destroying those that are noxious, or of preventing their ravages. 



An effort has been made to simplify the study of insects as much as 

 possible without sacrificing accuracy in the descriptions. Only such 

 morphological terms have been used as were necessary to accomplish the 

 object of the book in a satisfactory manner. And so far as possible a 

 uniform nomenclature has been used for all orders of insects. The fact 

 that writers on each order of insects have a peculiar nomenclature has 

 been a serious obstacle to the progress of entomology; this is especially 

 true as regards the nomenclature of the wing-veins. It has been neces- 

 sary for the student in passing from the study of one order of insects to 

 that of another to learn a new set of terms ; and in many cases writers on 

 a single family have a peculiar nomenclature. 



The present writer has endeavored to remove this obstacle by making 

 a serious study of the homologies of the wing-veins, and by applying the 



