THE WINGS OF INSECTS 



CHAPTER I 



THE GENESIS OF THE UNIFORM TERMINOLOGY OF THE 

 WING-VEINS OF INSECTS 



From the earliest days of systematic entomology to the present, much 

 use has been made of the wings in the classification of insects. The names 

 of the Linnean orders were all suggested by the nature of the wings except 

 one, Aptera, and that by the absence of wings; many of the established 

 families of insects are most easily recognized by peculiarities in the form of 

 the wings; and hundreds of genera have been distinguished by details of 

 wing-venation. 



A reason for the extensive use of characteristics of wing-structure in the 

 classification of insects is the ease with which they can be observed. Owing 

 to the broadly expanded form of the wings, it is more easy to see variations 

 in their structure than it is to see variations in the form of other parts of the 

 body. The wings are open pages upon which are to be read, with compara- 

 tive ease, the results attained by the processes of evolution. 



Although the wing-characters have been used in the classification of 

 insects from a verv'' early period, a full appreciation of their importance for 

 this pur]Dose is a matter of comparatively recent growth. It was not until 

 it was demonstrated that the wings of all winged insects are modifications of 

 a single primitive type that it was possible to fully understand the taxo- 

 nomic value of these organs. 



The early entomologists who worked without the aid of the modem 

 conception of organic evolution, only vaguely attempted to recognize those 

 homologies of the principal wing-veins that we now know to exist. The 

 result was the establishment of many different systems of terminolog}'-, the 

 students of each order having a system of their own, and in some cases 

 several different systems were used by the students of a single order. 



It would require too much space to explain all of these systems. The 

 student who uses the older books will need to leani the particular system 

 employed by the author he is studying. In later chapters, under the dis- 

 cussion of the venation of the wings of the separate orders, a table is given, 

 when practicable, in which one or more of the older s>-stems is compared 

 with that of Redtenbacher and with the one adopted in this work. 



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