250 THE CANADIAN ENTOMOLOGIST 



F. Two very small dots on median 

 carina between an- 

 tenna? H. tripunctata. 



FF. No dots on median carina; thorax 



and top of abdomen dark. 



G. Reddish area in pterostig- 



matic space of 



wing . . .H. ruhromaailata, 



GG. Without reddish area in 



wing. . . .H. Jitridipennis. 



AA. Two black spots or bands on face below antennae. Group 2. 



H. A black band on face below 



antennae, a dark dash in wing, 



abdomen dark. . H. canadensis. 



HH. A black spot on face below 



antennae, no dash in wing, 



abdomen lighter. .H. frontalis. 



Ke}^ to Nymphs : 



A. Gills oblong. Group 1. 



B. Nymphs entirely brown, without a distinct dorsal colour 

 pattern. 



C. An inverted dark U-shaped mark on ventral sur- 

 face of 9th segment and a dark spot on ventral 

 surface of the 8th. Dorsal surface of body has 



a smooth appearance H. flavescens. 



CC. A row of dark mushroom-shaped marks along ven- 

 tral surface and a rectangular dark mark on 9th. 

 Dorsal surface has a rather granular appear- 

 ance and lateral margins of body quite 



hairy H. rnhromacidata. 



BB. Nymphs not entirely dark brown and have a distinct 

 colour pattern. 



D. Ventral surface of abdominal segments 

 banded with dark bands along posterior 

 margins. 



E. Broad dark bands at posterior margin 

 of each segment on dorsal 

 surface II. fiisca. 



