CHAPTER VIII 

 THE WINGS OF THE ISOPTERA 



(a) THE MORE GENERAL FEATURES OF THE WINGS OF THE ISOPTERA 



In these social insects, in which each species consists of several castes, 

 only the sexual forms are winged. These have four, long, narrow wings, 

 which are somewhat leathery in stmcture, and which are furnished with 

 numerous veins. The wings are large, extending far beyond the end of the 

 abdomen, when folded upon it, as they are when at rest. Except in a single 



Fig. 126. — Wings of Termopsis angusticollis. 



genus, the two pairs of wings are similar in form and in the more general 

 features of their venation (Fig. 126). In the Australian genus Mastotermes 

 (Fig. 127) the hind wings differ from the fore wings in having a broadly 

 expanded anal area. The veins of the anterior part of the wing are greatly 

 thickened and those of the middle portion reduced to indistinct bands or to 

 narrow lines. Regular cross-veins are lacking, the membrane of the wing 

 being strengthened by an irregular network of slightly chitinized wrinkles. 

 Sometimes in narrow spaces, these wrinkles are transverse and resemble 

 cross-veins more or less. This is the case in the sub-costo radial area of the 

 wings oi Mastotermes (Fig. 129). 



(132) 



