PREFACE. 
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 affini¬ 
ties 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 im¬ 
possible. Excellent treatises on particular groups of insects 
have been published ; but no general work including analyt¬ 
ical 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 de¬ 
gree of completeness in this work which exists in the man¬ 
uals 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 possible to prepare it. An elementary work 
on systematic entomology will always of necessity be re¬ 
stricted 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 
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