304 



The Large Poplar Longhorn 



in form, and almost cylindrical in section. It varies in length from 

 4-5 mm. when newly hatched, to about 37-5 mm. or over when fully 

 grown. 



It is broadest across the first thoracic segment, and gradually tapers 

 towards the tip of the abdomen. The body is deeply wrinkled and is 

 covered with fine scattered hairs. 



The larva is made up of the chitinous head-piece and thirteen seg- 

 ments, the first three of these forming the thorax, the remaining ten 

 the abdomen. 



The head portion is highly chitinised and posteriorly is deeply sunk 

 in the first thoracic segment. 



ept 



a s m 



Fig. 4. Head of larva, S. carckarias, seen from above (greatly magnified). a=antenna; 

 asm = attachment area of the superior retractor muscles of the head; c = clypeus; 

 epi = epicranium ; e^s=epistome; et = epicranial suture; /=frons; /s=frontal suture; 

 £ = labrum; m = mandible; ms = median suture; o = ocellus; ps = pleurostome. 



The thoracic segments are somewhat larger than the abdominal ones. 

 The eighth and ninth abdominal segments taper posteriorly and are 

 smaller than the others, while the last or tenth segment is made up of 

 three lobes surrounding the anus. 



There are ten pairs of spiracles, the first pair being the largest. 

 The first pair of spiracles lie in a hollow between the first and second 

 thoracic segments. The second pair, which are very small, are present 

 on the third thoracic segment while the other pairs are borne by the 

 first eight abdominal segments. Each spiracle is oval in shape and is 

 surrounded by a chitinous ring. 



