ENTOMOLOGY IN OUTLINE STRUCTURE OF INSECTS. 



21 



R3 



R4 



2dA 



them. In earwigs and beetles the first pair of wings are represented by 

 a hard, horny wing covering, known as the elytra. The upper wings 

 are designated as superiors, anteriors or primaries, and the hinder wings 

 as posteriors or secondaries. 

 Commonly they are known as 

 fore and hind wings, which is 

 good enough for practical use. 

 The wings of an insect may 

 be compared to a boy's kite, 

 in which a light membrane 

 is tightly stretched over a 

 tough framework. In the 



insect we find a Strong frame- FIG. 21. Wings of a butterfly U/iosm). A, anal vein; 

 work Of horny tubes, termed C.costa; Cu.cubitus; M, media; R, radius. Sc.sub- 

 J costa. (After Comstock and Needham.) 



veins or nerves, with a tough, 



membranous film on either side. The arrangement of these veins is 

 called the venation or neuration, and is exceedingly variable, so much 

 so that expert entomologists can tell to what order or family, and 

 often to what species, an insect belongs by the arrangement of its 



wing veins. The 

 spaces between 

 the veins are 

 termed cells. 

 With all this 

 variation, how- 

 ever, in all wings 

 there are certain 

 well - marked 

 veins, common 

 to all, and these 

 have all been 

 named and num- 

 bered. The prin- 

 cipal veins are 

 known as the 

 costa, subcosta, 

 radius, cubitus, 

 media, and anal. 

 These are found 

 in some form 

 in all wings. 



Insect wings vary not only in form, but also greatly in color and 

 texture, and among them, especially in the butterflies, moths, and 

 beetles, we find the most exquisite expression of color, form, and 

 arrangement in nature. 



FIG. 22. Ovipositor of Locimtd. A. lateral aspect; B, ventral aspect: 

 C, transverse section; c. cerci; d, dorsal valve; i, inner valve: 

 v, ventral valve. The numbers refer to abdominal segments. 

 (After Kolbe and Dewitz.) 



