308 



THE WINGS OF TRICHOPTERA 



wings; in one species the female is apterous and in another the wings of the 

 female are vestigial. When not in use the wings are folded roof-like over 

 the abdomen. 



The posterior lobe of the fore wings is specialized as a fibula, which is 

 well-developed in the more generalized forms, as Rhyacophila, but more or 

 less reduced in the more specialized genera. The costal border of the hind 

 wings is furnished with hamuli in some forms, as in the Leptoceridae and in 

 the Macronematinse. 



{b) THE TRACHEATION OF THE WINGS OF THE PHRYGANEINA 



It was shown by Comstock and Needham that the tracheation of the 

 wings bears but little relation to the wing-venation; this being one of the 



orders in which the trachea- 

 tion of the wings is greatly 

 reduced. If a wing of a 

 pupa of a caddice-fiy be 

 examined after the cavities 

 of the developing wing-veins 

 have been formed it will be 

 seen that usually only two 

 or three main trachea are 



T.. „r. r r , -,■ r, present; and that although 



Fig. 319. — Wmg of a pupa of a caddice-flv. . • ■ -, • , 



these may comcide with 



forming veins, their branches bear no relation whatever to the veins 



(Fig. 319). 



(c) THE PHRYGANEID TYPE OF WING-VENATION 



As the tracheation of the wings of pupae of the aquatic Trichoptera 

 affords no help in the determination of the homologies of the wing-veins, 

 we are forced to base our conclusions regarding these homologies on studies 

 of the wings of adults. Fortunately in the more generalized members of 

 this suborder it is easy to identify the veins; and the conclusions that have 

 been reached regarding the homologies of the wing-veins of the Phry- 

 ganeina are confirmed by a study of wings of ten-estrial Trichoptera in 

 which the wing-trachea are presei^ved. 



The wings of Rhyacophila fuscida (Fig. 320) can be taken as illustrating 

 the phryganeid type of wing-venation. Beginning at the costal margin of 

 the jore wing and proceeding backward the following features can be 

 observed. 



The subcosta of the fore wing is forked ; the forking takes place near the 

 tip of the vein; and vein Scs is connected with vein Ri by a cross vein. 

 Near the middle of the length of the subcosta, an accessory vein (Fig. 



