234 



COLLEGE ZOOLOGY 



Sc, Scj 



NAMES OF 

 WING VEINS: 



Costa „C 



Subcosta _Sc 



Radius ^__„.R 



Media M 



Cubitus. Cu 



Ist anal vein .1A 



2nd anal vein 2A 



3rd anal vein 3A 



Trachea 



Blood space 



Figure 134. A, generalized insect wing showing the chief veins. B, cross section of wing. 

 C, enlarged cross section of wing showing a vein which consists of the outer surface of the 

 wing, blood space, and trachea. (A from The Wings of Insects, by J.H. Comstock. Copyright 

 1916 by The Comstock Publishing Company.) 



Dorsal longitudinal muscle 

 Tergum 



-Tergosternal muscle 



Sternum 



Figure 135. Movement of wings in flight. A, the wings are elevated on the pleural wing 

 processes by the depression of the tergum due to the contraction of the tergosternal muscles. 

 The hind margins of the wings are deflected. B, the wings are lowered by the elevation of the 

 tergum due to the contraction of the dorsal, longitudinal muscles. Hind margins of wings are 

 elevated. (After Snodgrass.) 



to 8 are unmodified. In the male, the 

 sternum of segment 9 is elongated ventrally, 

 giving an upward twist to the abdomen. The 

 end of the female abdomen is more taper- 

 ing than that of the male and forms the 

 ovipositor, an egg-laying apparatus, 



internal anatomy 

 and physiology 



The systems of organs within the body 

 of the insect (Fig. 136) lie in the body 

 cavity, which is filled with blood and is a 



