308 



The Large Poplar Lotighorn 



in size to the other two taken together. Besides differing in size, the 

 prothoracic segment differs considerably in structure from the other two 

 thoracic segments. 



Viewed from the side the prothorax shows the following regions: 

 dorsally the large pronotum (p), laterally the pleural lobe (p>l), and ven- 

 trally the eusternum (es) 1 and the sternellum (stl). The mesothoracic 

 and the metathoracic show, in side view, the mesonotum and metanotum 

 respectively on their dorsal surface, the pleural lobe medially, and the 

 eusternum (es) and sternellum (stl) ventrally (see Fig. 10, b). Ventral 

 to the pleural lobe and lying between it and the eusternum and sternellum, 



Fig. 8. Head of larva of S. carcharias, seen from below ; the maxillae, labium, and mandibles 

 removed (greatly magnified). a=antenna; c = clypeus; epi = epicranium; <7=gular 

 plate or gula; hm = muscles in head; hs = hypostome ; Z = labrum; 111 =labral hooks; 

 to/= maxillary foramen; o — ocellus; o/= occipital foramen; ps = pleurostome ; ^ten- 

 torium. 



is the hypopleurum (hyp). Situated in a cavity between the prothorax 

 and the mesothorax is the large thoracic spiracle, while on the metathorax 

 lies the small spiracle. 



The Abdomen (Fig. 3, ft). 



The first seven abdominal segments are similar in structure to each 

 other and show the following regions: the swollen parascutal lobe (pa) 



1 The terminology used in this description of the larva is that adopted by F. C. Craig- 

 head in Report No. 107, U.S. Dept. of Agriculture, 1915. "The Larvae of the Prioninae." 

 See also, A Preliminary Synopsis of Cerambycoid Larvae, by J. L. Webb, Tech. Series, 

 No. 20, Part V, Bureau of Entomology, U.S. Dept. of Agriculture, 1912. 



