INS^CUTOR INSCITI^ MENSTRUUS 131 



Scutellum with long, slender bristles ; pile rather sparse, 

 species appearing shining black (Ontario, New York, New 

 Hampshire, North Dakota) orilliaensis Curran. 



17. Antennae bright reddish yellow 18 



Antennae dark brown 21 



18. General color dark steel blue ; thoracic pile largely black 19 



General color greenish black; thoracic pile luteous (Washing- 

 ton, Idaho, Oregon) petulca Will. = hoodiana Bigot. 



19. Halteres dark brown; pile on pleurae and scutellum largely 



luteous (New Mexico) sonoriana, n. sp. 



Halteres reddish yellow ; scutellar pile mostly black 20 



20. Pleural pile mostly black ; scutellar pile short ; head higher 



than broad, small species (New Hampshire) pontiaca, n. sp. 



Pleural pile equally luteous and black; scutellar pile long; 

 head broader than high ; medium sized species (Oregon, 

 Washington) hurkei, n. sp. 



21. Legs entirely black (Europe) variabilis Panz. 



Legs partly brown or black 23 



22. Apical cross-vein sinuate ; tibiae yellow with medium broad 



black bands; small, eastern species (Virginia, Maryland, 



Pennsylvania) primoveris Shann. 



Apical cross-vein parallel with wing margin except on distal 

 end where it is turned upright; tibiae black and brown 

 (western species) 23 



23. Arista shorter than width of frons measured across base of 



antennae (Alaska) yukonensis, n. sp. 



Arista equal to width of frons (California, Colorado, New 



Mexico) pacifica-occidentalis complex. 



Cartosyrphus — Males 

 Eyes bare; antennal pits confluent 



1. Arista with long, or dense, plumosity which can be perceived 



with naked eye (subgenus Hiatomyia) 2 



Arista very short plumose to bare (subgenus Cartosyrphus) 8 



2. Arista very densely plumose for more than one-half its length ; 



third antennal joint large, bright yellow; mesonotum with 

 long black hairs intermixed with the luteous pile (Idaho), 



signatiseta Hunter. 

 Arista with long, loose rays 3 



3. Thorax shining deep steel blue 4 



Thorax black or greenish black 5 



4. Face less than one-third the width of the head ; facial strips 



very narrow (eastern North America), 



plumata Lw. and cyanesccns Lw. 



