PROCEEDINGS OF THE 



ENTOMOLOGICAL SOCIETY OF WASHINGTON 



VOL. 23 JANUARY 1921 No. 1 



THE MOUTH PARTS OF THE CICADA. 



BY R. E. SNODGRASS, Bureau of Entomology. 



This paper is presented to show the anatomical structure of 

 the sucking apparatus of the cicada (Tibicena septendecim). 

 None of the published accounts of Hemipteran mouth parts 

 have made the subject fully clear to the writer, and it is hoped 

 that the descriptions and figures here given may justify a new 

 treatment of an old subject. But the facts are disconcerting 

 they raise perplexing questions of interpretation that will not 

 fit with any current view on the homologies of the Hemipteran 

 head plates and the setae. While the basic mouth structure 

 appears to be the same throughout the order of the Hemiptera, 

 a further study of the embryological origin and development of 

 the head plates and the mouth appendages is needed. The 

 intricate mechanism in the adult is difficult to set forth clearly 

 in words and for this reason the figures on plates I and II are 

 made the basis of the descriptions and comparisons. 



Figure 1 (Plate I) represents the head of a young Locustid, 

 showing the generalized type of Orthopteran mouth parts. 



Figure 2 is the same with the mandible removed from its 

 basal connection (md], exposing the large tongue-like hypo- 

 pharynx (Hp/iy) and its lateral membranous connection (a) 

 with the base of the mandible. 



Figure 3 is the same again but with both the mandible and the 

 maxilla cut off, leaving the stump (mx) of the latter still attached 

 to the head. 



Figure 4 shows a corresponding view of the head of a fully 

 matured adult seventeen-year cicada. The prominent ridged 

 facial plate (Ft) is designated the front because of the attachment 

 of the pharyngeal muscles (Plate II, figure 15, PhyMcl) to it as 

 in other insects. The labrum-like plate below (Clp) is called 

 the clypeits because it appears to correspond with the clypeus 

 of the Locustid (fig. 1, Clp). The tapering appendage (Liu), 

 ensheathing the bases of the setae, likewise appears to be the 

 labrnm, though some writers call it the epipharynx. On the 

 side of the head are two important sclerites (//ami #) which 

 will be referred to simply by the letters designating them. The 

 second one (B) terminates below in a tree lobe (/>) carrying a 

 soft appendage (r) which, with its mate on the other side, pro- 



