THE WINGS OF APHIDID.^ 



285 



In the adult wing the first anal vein is not developed as a vein but is 

 represented by the anal furrow, or the calval suture as it is termed by 

 writers on the Homoptera. The other changes are indicated by the letter- 

 ing of Figure 287. 



The stigma. — In some of the Psyllidae the costal margin of the fore wing 

 is strengthened by a stigma. 



Fig. 287. — The venation of a fore wing of Psylla 

 floccosa (After Patch). 



(/) THE WINGS OF THE APHIDID^ 



The tracing of the homologies of the wing veins of the Aphididaj was 

 the subject of a painstaking investigation by Miss Patch ('09) ; in the course 

 of which approximately 100 species representing 17 genera were studied, 



Fig. 288.- — The tracheation of a wing of a nymph of 

 Schizmxeura rileyi (After Patch). 



and wings of many nymphs and of more than 2000 newly emerged aphids 

 were examined. The following brief simimar}^ is based on this paper. 



A general view of the wing. — The most generalized aphid wdng figured 

 by Miss Patch is that of a nymph of Schizoneiira rileyi (Fig. 288). In this 

 wing there are four main tracheal tnmks, which arise from a transverse 

 basal trachea. The costal and subcostal trachese are lacking; and only 



