76 NORTH AMERICAN DIPTERA 



KEY TO GENERA 



1. Empodium as long as claws 2 



Empodium very short or absent 3 



2. Costa extending to about middle of wing; wings with dense macrotrichia 



all over (Euforcipomyia Malloch) (3) Forcipomyia Meigen 



Costa extending well beyond middle of wing; macrotrichia sparser, 

 sometimes absent (4) *Atrichopogon Kieffei 



3. A fold looking like a simple vein between third and fourth veins; first 



and third veins indistinct, more or less fused. (Tersesthes Townsend). 



Leptoconops Skuse 

 No vein-like fold between third and fourth veins 4 



4. Costa extending to about middle of wing; second radial cell short and 



square-ended, first radial cell obliterated; macrotrichia usually dense 

 (Pseudoculicoides Malloch, Isoecacta Garrett) (5) . . . .Dasyhelea Kieffer 

 Costa extending well beyond middle of wing; radial cells usually other- 

 wise 5 



5. Humeral pits present and conspicuous; microtrichia of wings distinct; 



claws of female small and equal; at least some macrotrichia present. 



(^cacta Poey) (9, 10) fCulicoides Latreille 



Either humeral pits absent or else microtrichia absent or else claws of 

 female very unequal 6 



6. The two radial cells small and equal or one or both of them obliterated; 



wings finely punctuate but without distinct microtrichia; legs not 



thickened 7 



Either second radial cell much longer than broad or else wines with 

 distinct microtrichia or else legs modified 8 



7. Wings with at least one dark spot and with some macrotrichia; female 



claws unequal (Neoceratopogon Malloch) Alluaudomyia Kieflfer 



Wings whitish, without dark markings, and without macrotrichia; 

 female claws equal (8) Ceratopogon Meigen 



8. Hind femora noticeably thicker than the others 9 



Hind femora not thickened 10 



9. Hind femora much thickened and spinose beneath; hind tibiae not 



thickened (Ceratolophus Kieffer) (1) Serromyia Meigen 



Hind femora not spinose; both hind femora and hind tibiae moderately 

 thickened (7 ) M'onohelea Kieffer 



10. First and third veins connected by a crossvein, 2 radial cells 11 



First and third veins not connected, one long radial cell 15 



11. Front femora spinose beneath 12 



Front femora not spinose beneath 13 



12. Front femora conspicuously swollen Heteromyia Say 



Front femora not conspicuously swollen Palpomyia Meigen 



13. The branches of the fourth vein petiolate basally (Hartomyia Malloch). 



Stilobezzia Kieffer 

 The branches of the fourth \ein arise at or before the cross vein 14 



14. Last segment of front tarsi much swollen (2) Clinohelea Kieffer 



Last segment of front tarsi not swollen (6) Johannsenomyia Malloch 



* Malloch, 1915, Bull. 111. State Lab. Nat. Hist., x, p. 304 (Ceratopogon). 

 t Hoffman, 192.'i. Anier. Journ. Hygiene, v. pp. 274-301. 



