302 



The Large Poplar Longhorn 



A further distinguishing sex character, noticeable in the majority 

 of my northern specimens is that of colour. The majority of the males 

 are dark ash-grey, while all the females are greenish-yellow. Later in 

 this work I refer to this difference in colour between the sexes. 



Fig. 2. The large poplar Longhorn, S. carcharias L. Female. Tarsal claws of a leg are 

 shown on the right (both greatly magnified). 



Xhe principal external differences in the sexes may be thus con- 

 trasted : 



Male (see Fig. 1) Female (see Fig. 2) 



Size ... ... ... 18 mm. -22-5 mm. 24-5 mm. -27-5 mm. 



Length of antennae ... Longer than body Shorter than body 



Shape of prothorax ... Quadrate Broader than long 

 Tarsal claws of 1st and One claw bifid or toothed Simple 

 2nd pairs of legs 



Breadth of elytra at 7 mm.-7-5 mm. 8*5 mm.-9-5 mm. 



Shape of elytra ... Outer margins taper Outer margins taper less 



markedly towards apices markedly towards apices 



Shape of abdomen ... Thin; groove on 5th Stout; groove on 5th 

 sternite absent sternite present and con- 



spicuous 



