76 THOMAS SAY FOUNDATION 



12. Male with a distinct apical midventral lobe on 



abdominal segment 7. Larger northern species 



hastata 



Male with no lobe on segment 7 ; smaller eastern 

 species fugitans 



13. Black species, with 3-lobed yellow spot on rear 



of head nona 



Small pale species (max. expanse 30 mm.) with 

 apical ventral lobe on 7th abdominal segment 

 of the male 14 



14. Three pale spots in a row across the rear of the 



head aestivalis 



Yellow confluent across rear of the head 15 



15. Yellow middorsal stripe of prothorax covering 



about a fourth of the width of the pronotum, 

 not much constricted before the middle — West- 

 ern modesta 



Yellow middorsal stripe of prothorax covering 

 much less than a fourth of the width of the pro- 

 notum and strongly constricted before the mid- 

 dle — Eastern vert icalis 



16. Rs forked far beyond the cord; fusion of veins 



Rs and M in hind wing short, about a sixth the 



length of the disc tincta 



Rs with basal fork close to or involved in the 



cord ; fusion of Rs and M in hind wing longer, 



equaling one-third the length of the wing disc 



sorpta 



17. Median vein 3- to 4-branched 18 



Median vein 2-branched phalerata 



18. Legs blackish with no distinct pattern of yellow 



obscura 



Legs brown with light yellow half rings before 

 the knees venosa 



19. Wing expanse 24 to 29 mm. Supra-anal process 



of male double duplicate, 



Wing expanse 18-24 mm. Supra-anal process of 

 male single, telescopic bilobata 



20. Cubito-anal crossvein opposite the apex of the 



anal cell, or very close thereto 21 



Cubito-anal crossvein situated distinctly before 

 the apex of the anal cell capitata 



