Economic entomology, as now understood, is a new science 
and does not date much beyond 1850. It deals with the insects in 
their relation to man together with the means used for controlling 
them. Such a great advance has been made in this subject within 
the past few years that it now ranks ahead of the older, more tech- 
nical side of the subject. 
However, the two subjects are so closely related that they can 
no more be separated than the bookkeeping system can be separ- 
ated from the manufacturing end of a large corporation. 
The insects must be named and classified and the scientific 
name recorded, together with the descrpition of the species, or we 
cannot tell whether the insect which we are studying is the same 
as the one described in the literature. 
The two subjects are so closely related that many of the tech- 
nical terms used in both sciences must be learned before the liter- 
ature can be understood. 
Study the rest of your Elementary Entomology and where 
possible collect and study the insects as outlined in the back of this 
book. Pay special attention to the external anatomy and to the 
structure of the mouth parts. It will be impossible for you to de- 
cide upon the correct remedy, in many cases, without knowing how 
the insect takes its food. 
In studying these lessons, refer frequently to Lesson 8 until 
you understand the use of the remedies, there described, in control- 
ling the different insects. Also review your earlier lessons, in your 
Elementary Entomology, until you know the characteristics of the 
different orders. 
The bibliography furnished with the lessons will help you in 
getting additional literature upon the different species. 
