CHAPTER VII. 

 THE VENATION OF THE WINGS OF INSECTS.* 



INTRODUCTION. 



In form an insect's wing is a large, membranous append- 

 age, which is thickened along certain lines. These thick- 

 ened lines are termed the veins or nerves of the wing ; and 

 their arrangement is described as the venation or neuration of 

 the wings. 



It has been found that the venation of the wings of closely 

 allied insects is very similar, and that great differences in 

 this respect exist between insects remotely connected. Hence, 

 the wings afford excellent characters for use in the classifica- 

 tion of insects. In fact, as slight differences in venation are 

 easily observed, the wings being spread out like an open 

 page, these differences are probably the most available char- 

 acteristics of winged insects for taxonomic work. It is im- 

 portant, therefore, that the student of entomology should 

 learn early in his course the more important facts regarding 

 this subject. 



A careful study of the wings of many insects has shown 

 that the fundamental type of venation is the same in all of 

 the orders of winged insects. But this fact is evident only 



'The material for this chapter has been drawn largely from an essay by the 

 writer, entitled Evolution and Taxonomy, published in The Wilder Quarter- Cen- 

 tury Book, Ithaca, 1893, and from a series of articles entitled The Wings of In- 

 sects, by J. H. Comstock and J. G. Needham, published in The American 

 Naturalist, vol. xxxii. (1898), and vol. xxxiii. (1899). 



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