THE WINGS OF I SOFT ERA 



133 



The wings are deciduous, being shed after the swarming flight. The 

 shedding of the wings is facihtated by the presence in each wing, except in 

 the hind wings of certain genera, of a curv^ed transverse suture near the 

 base of the wing, which may be termed the humeral suture (Fig. 128, hs). 

 In the more generahzed members of the order, this suture is present only 

 in the fore wings ; but in the more specialized genera it exists in the hind 

 wings as well. 



That portion of the wing that is between the humeral suture and the 

 body, and which remains attached to the body throughout life is more 

 densely chitinized than the remainder of the wing. This part of the wing 



Fig. 127. — Mastotermes darwiniensis , adult male 

 (After Froggatt '13). 



is tenned the scale by most wTiters on the Isoptera; 

 Froggatt calls it the scapular shieki, which is a 

 much more distinctive term. 



The scapular shield is traversed by the median 

 furrow (Fig. 128, mf) and the anal furrow (Fig. 

 128, F). The position of the anal furrow indi- 

 cates how greatly the anal area of the wing is 

 reduced in the fore wings; in the hind wings the extent of the anal area 

 varies in different genera, as is shown later. 



The termite type of ^ving is a distinctively characteristic one and was 

 evidently evolved very early. This is shown by the absence of regular 

 cross-veins. It is obvious that the teiTnites branched off from the insect 

 stem before regular cross- veins were evolved; and it is an interesting fact 

 that the tendency to develop regular cross- veins has not arisen in this order; 

 instead of this there is a reduction in the chitinization of the irregular net- 



