THE WING VENATION OF THE JASSIDAE. 



Z. P. Metcalf. 



The present paper was undertaken several years ago at the 

 suggestion of Professor Herbert Osborn. At that time it was 

 thought that the wing veins of Homopterous insects could be 

 identified in the adult stage by carefully comparing them with 

 the venation of the Cicadidas as determined by Comstock and 

 Needham '98-'99. This, however, was found to be impractic- 

 able as it was soon discovered that the wing veins of most of 

 the Homoptera have been greatly reduced and much modified 

 from the Cicadid type. The study was then discontinued 

 until the spring of 1910, when it was resumed by studying it 

 from the standpoint of the nymphal wing pads. 



At first the wing pads were removed as carefully as possible 

 and mounted in glycerine jelly, as recommended by Comstock 

 and Needham '98-'99. Later on many wing pads were mounted 

 in xylene damar as recommended by Miss Patch '09. It was 

 soon discovered, however, that just as good results could be 

 obtained by mounting the wing pads in water. These wing 

 pads were then either photographed or drawn with the aid of 

 the camera lucida. For most Jassidae it was found more satis- 

 factory to draw them with the camera lucida. This is due to 

 the fact that the outer covering of the wing pad is very thick 

 and frequently dark colored. In addition many of the wing 

 pads were so thick that, using the high powers necessary, it 

 was found to be impossible to bring all parts of all the tracheae 

 into sharp focus at the same time. This lead to some confusion 

 as many of the wing pads are provided with long spines which 

 make the interpretation of the tracheae difficult, as many of the 

 spines are so placed as to appear in photographs as branches of 

 the tracheae which are slightly out of focus. 



After the drawings were finished they were carefully com- 

 pared many times over with wing pads from nymphs collected 

 at later dates. If any marked differences were noted drawings 

 were made and these again compared with the pads from 

 nymphs collected at later dates. In this way, it is believed 

 that all errors that might arise have been corrected or elimin- 

 ated. The nymphal wing pads shown in the plates have been 

 carefully selected from these drawings or redrawn from pho- 

 tographs. 



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