THE CANADIAN ENTOMOLOGIST 153 



Abdomen not' so shaped • 9 



9. Face with a median brownish or blackish stripe ; femora of hind legs with 



brownish band ; venter with alternate black and yellow bands 



$ ribesii vittafrons Shan. 



Face with median dark stripe 10 



10. Venter unicolorous ; abdominal bands not much attenuated laterally and 



seldom notched posteriorly ; the spots on the second segment reach 

 the margin in almost the full width of one spot ; smaller, seldom 



over 9 mm ? rectus O.S. 



Venter usually with alternate yellow and black bands, but these sometimes 

 very faint or represented by isolated spots ; spots on second segment 

 reach the margin in not more than half the width of the spot; abdominal 

 bands always distinctly notched posteriorly and attenuated laterally . . 

 5 ribesii L. 



11. Antennse red; hind femora with about the apical third yellow; tiny black 



bristles on end oi femora sparse, sometimes they are almost all pale; 

 hind tibiae with a moderately narrow, more or less obscure postmedian 



band darker c^ vitripcnnis Mg. 



Flies without all these characters 12 



12. Face with a median blackish or brownish stripe . . J^ ribesii vittafrons Shan. 

 Face wholly yellow 1 ^ 



13. Venter unicolorous ; first band or spots reach the lateral margin of the 



segment in at least half the width of the spots ; pile of vertex more 



tawny; fewer small black bristles on hind femora (about 9) 



<^ rectus O.S. 



Venter as in couplet 10-2; first abdominal band reaches the sides very 

 narrowly; pile of vertex pale yellow (about 11 or 12 mm.) . .($ ribesii L- 



14. Antennae black ; abdominal bands extended over side m.argins in their full 



width ; eyes bare J* ? grossulariac Mg. 



Antennae more or less reddish 15 



15. Eyes pilose ; face with median black stripe $ reflectipennis n. sp. 



Eyes bare; face sometimes with m.edian black stripe 1^' 



16. Face with median dark stripe 17 



Face without median dark"" stripe ; antennae reddish 18 



17. Female bands reach the margins in their full width ; base and tip of hind 



femora yellow (Eastern species) ? gcnnalis Will. 



Female bands attenuated hterally and moderately biconvex posteriorly; 

 hind femora yellow, with brownish band on apical half ; male very 

 similar to S. rectus (Western species) rectcides n. sp. 



18. Scutellum yellow haired ochrostoiiiiis 7.ett. 



Scutellum black haired nitidicollis Mg. 



Note: S. xanthostomiis Will, differs from S. oehrostoiiiiis in having the abdominal 

 bands very wide and not at all metallic. 

 . Verrall (Brit. Fl., vol. viii.) states that the venter of S. ribesii is usually 

 unicolorous. I have an English specimen in which it is as described 

 above ; other Canadian specimens show very light markings, but I 

 think there are always sufficient darker markings present to readily 



