AGROMYZID LEAF MINERS — FPJCK 351 



Mesonotum shining black and yellow, or if gray poUinose then either four 

 rows of acrostichals, or crossvein m-m present, or two upper-orbital setae 

 present 7. Liriomyza 



11. Crossvein m-m, when present, never basal to crossvein r-m; basal section of 



M3+4 present (fig. 134) 12. Phytagromyza 



Crossvein m-m basal to crossvein r-m and appearing to be the basal section of 

 vein Ms+i, which is absent (fig. 135) 13. Pseudonapomyza 



12. Costa reaching to the end of vein M1+2; halter with a dark spot on knob. . 13 

 Costa reaching to the end of vein R4+5; halter white or yellowish 14 



13. Wing with axillary lobe and calypter well developed; mesonotum with 



acrostichal setae present 10. Phytoliriomyza 



Wing with axillary lobe very small and calypter virtually absent; acrostichal 

 setae absent 11. Xyraeomyia 



14. Wing with crossvein m-m present 14. Napomyza 



Wing with crossvein m-m absent 15. Phytomyza 



Systematic Treatment 

 1. Genus Agromyza Fallen 



Agromyza Fallen, Specimen entomologicum novam Diptera disponendi methodum 



exhibens, p. 21 (No. 66), 1810 (Dissertat. Lund.). 

 Domomyza Rondani, Dipt. Ital. Prodr.^ vol. 1, p. 121, 1856. 



This is a moderately large genus of 22 described species that has the 

 subcosta complete and uniting with vein R, at the costa, which is ex- 

 panded at that point (fig. 1), and the halteres white. The only species 

 that I have seen that has the union of the subcosta and vein Ri with 

 the costa atypical in some specimens is Agromyza aristata. However, 

 most of those examined have the typical costal union (fig. 4). The 

 most diverse types have the subcosta about one-fourth incomplete 

 and Ri distinctly bent but not expanded near the costa. 



There are no diverse species that deviate from the Palaearctic 

 pattern. The great majority of North American species have only 

 two or three well-developed dorsocentrals with none to several small 

 ones. Only four species have the usual arrangement of one strong 

 presutural and three strong postsutural dorsocentrals. In the Palae- 

 arctic region there are proportionatel}'^ more species with the latter 

 arrangement. 



As for the species groups, there are representatives in the rubi group 

 (couplets 3-5) but none in the cinerascens group, which contains three 

 European species. The correlation between shining mesonota and 

 grass mining larvae (ambigua group) holds true in North America as 

 in the Palaearctic region. Of the six known North American species 

 (couplet 14), four have larvae that mine the leaves of grasses. The 

 alternative (couplets 7-13) contains eight species that have the 

 mesonotum subshining to dull and larvae that mine in dicotyledons. 

 The host plants are known for four. 



One of the more unusual features of the North American fauna is 



