350 PROCEEDINGS OF THE NATIONAL MUSEUM vol. los 



historsches Museum, Vienna; and Harald Schweiger, Niederoster- 

 reichischen Landesmuseum, Vienna. So many individuals kindly 

 lent specimens from various parts of the United States that space 

 does not permit thanking each personally. I am thankful for reared 

 and authentically identified European specimens for my collection 

 from E. M. Hering, Arne Lundqvist, and K. A. Spencer. Marion 

 Ownbey, Department of Botany, State College of Washington, kindly 

 helped to bring the names of larval host plants up to date. 



Key to the genera of Agromyzidae found in North America 



1. Subcosta developed throughout its length, coalescing with vein Ri before 



reaching costa; vein Ri somewhat broadened at union with the costa (fig. 1) 



(Agromyzinae) 2 



Subcosta becoming a fold distally and ending in costa separately and basad of 

 vein Ri; Ri not broadened at its union with the costa (fig. 2) (Phyto- 

 myzinae) 5 



2. Halter usually all black, rarely with a white spot on knob 3 



Halter white or yellowish 1. Agromyza 



3. Carina between antennae prominent, fusiform or hemispherical, antennae 



somewhat divergent (fig. 45) 4 



Carina absent, flattened between antennae even though bases widely separat- 

 ed; antennae anteriorly directed 2. Melanagromyza 



4. Carina fusiform (fig. 45); orbital setulae erect or reclinate (fig. 47). 



3. Ophiomyia 

 Carina hemispherical; orbital setulae proclinate (fig. 55). ... 4. Tylomyza 



5. Scutellum with four setae (fig. 99) 6 



Scutellum with two setae (fig. 95) 6. Cerodontha 



6. Orbital setulae erect or reclinate (fig. 133), sometimes weakly developed, or 



absent 7 



Orbital setulae proclinate, well developed (fig. 141) 12 



7. Wing with costa reaching to end of vein M1+2, or (Phyiobia) if only to R^+s 



then ultimate section of M3+4 subequal to the penultimate section (fig. 



77) 8 



Wing with costa reaching to end of vein R4+5; ultimate section of M3+4 at 

 least twice as long as penultimate section when crossvein m-m present 

 (fig. 134) 11 



8. Scutellum yellow, at least centrally; vein M1+2 ending nearest wing tip (fig. 



118) 9 



Scutellum usually dark and concolorous with mesonotum, if yellow vein 

 R4+6 ending nearest wing tip (fig. 60) 5. Phytobia 



9. Genovertical plates narrow, usually sUghtly but not abruptly raised above 



the plane of the frontal vitta; if abruptly raised then genovertical plates 



narrow except dorsad of antennae (fig. 104) 10 



Genovertical plates broad, about one-third the width of the frons and very 

 abruptly raised above the plane of the frontal vittae (fig. 128). 



8. Metopomyza 



10. Mesonotum dull black, heavily gray poUinose; two sparse rows of acrostichal 



setae; crossvein m-m absent; only one upper-orbital seta, reclinate and 



outwardly directed (fig. 129) 9. Haplomyza 



