1	Subcostal vein well-developed along entire length and fused to vein R1 before reaching costa (Fig. 4). Vein R1 sinuous for a short distance just before reaching costa, and sometimes thickened (relatively straight in some Agromyza, which has a distinct stridulatory file on lateral margin of tergite 2). Vein R4+5 ending as close, or closer to wing apex compared to vein M1. Lunule often with medial furrow, well-sclerotised and flat to bulging (recessed in some Agromyza and some poorly preserved material)	Agromyzinae (2)
–	Subcostal vein either ending freely in cell or continuing as a fold or atrophied vein to the costa (Fig. 3). Vein R1 straight, not deviated before reaching costa, infrequently thickened apically (excluding some Phytobia). Lateral margin of tergite 2 never with stridulatory file. Vein M1 usually closer to wing apex compared to vein R4+5 (except in Phytobia and some Nemorimyza). Lunule without medial furrow (except in some Phytobia), often soft, and usually flat or recessed (infrequently bulging)	Phytomyzinae(8)
2	Prescutellar acrostichal seta present (Figs 10, 51); halter usually white, at least apically	3
–	Prescutellar acrostichal seta absent and halter entirely dark (apically white in Ophiomyiamaculata Spencer)	4
3	Lateral margin of tergite 2 and fused tergite 1 with straight, thin, and well-sclerotised stridulatory file (Fig. 38). Usually at least three conspicuous dorsocentral setae (Fig. 10). Fore tibia without medial seta. Frons sometimes soft and pale; body never with metallic shine	Agromyza Fallén
–	Lateral margin of tergites 1 and 2 weakly sclerotised and sometimes irregular in outline, never with stridulatory file. Only two well-developed dorsocentral setae (Fig. 51), frons well-sclerotised, rounded and dark, and gena shallow (Figs 49, 50) (J.rutiliceps with four dorsocentrals, a projecting frons and gena ¼ height of eye); fore tibia usually with medial posterolateral seta; body sometimes with metallic shine	Japanagromyza Sasakawa (in part)
4	Clypeus with anterior margin truncated anteromedially (Figs 71, 73); sometimes narrowed (Figs 77, 80), often with conspicuous corners anteriorly and arms parallel. Sometimes with one or more of a pronounced facial keel that may have a medial bulb, an anteriorly produced gena, and multiplicated vibrissae forming a “fasciculus” or “horn” (Figs 75–77)	Ophiomyia Braschnikov
–	Clypeus rounded anteromedially; if slightly truncated (some Melanagromyza), then with one or more of the following characters: dorsal setulae on eye; one posteromedial seta on fore tibia; more than 1 posteromedial seta on mid tibia; entire thorax and abdomen strongly metallic. Gena sometimes angled anteriorly (M.buccalis, Fig. 53), but never forming a point; vibrissa single, simple	5
5	Fore tibia with small to well-developed posteromedial seta (Fig. 121)	6
–	Fore tibia bare posteromedially	7
6	Halter white. Costa extending to M1. Only two developed dorsocentral setae (Fig. 51). Ocellar triangle only reaching level of posterior fronto-orbital seta; frons and lunule smooth with minute pruinosity; orbital plate not raised (Figs 49, 50). Eye bare or with few small, inconspicuous ommatrichia. Epandrium without spine. Basiphallus asymmetrical; often with left and right sides divided (Figs 255, 256). Mesophallus (or if absent, insertion of ejaculatory duct) basal to distiphallus; often forked or membranous. Distiphallus without paired ventrobasal tubules	Japanagromyza Sasakawa (in part)
–	Halter brown. Costa extending to M1 or (uncommonly) R4+5. Usually two dorsocentral setae, uncommonly three or four. Ocellar triangle exceeding level of posterior fronto-orbital seta; frons variable, lunule smooth; orbital plate distinct and often raised or bulging (Figs 52–57). Eye often conspicuously with ommatrichia dorsally, particularly in males. Epandrium usually produced into small, but conspicuous spine posteroventrally (Fig. 267). Basiphallus symmetrical; ring- (Fig. 304) or U-shaped (Fig. 256). Mesophallus inserted ventromedially into distiphallus as a cylindrical chamber (Figs 264, 265). Distiphallus with paired ventrobasal tubules, often flanking mesophallus	Melanagromyza Hendel (in part)
7	Thorax (and sometimes head and abdomen) sometimes with green (Fig. 60), blue or coppery metallic sheen. Eye often conspicuously with ommatrichia, particularly in males. Orbital plate usually small, not much visible laterally, but sometimes prominent as below. Mid tibia with 1 or 2 posteromedial setae. Postsutural intra-alar setae unequal in length with anterior seta stronger. Epandrium usually with posteroventral spine (Fig. 267). Phallophorus simple, cylindrical (Figs 264, 265). Basiphallus symmetrical; ring-like or U-shaped. Distiphallus with paired ventrobasal tubules, often flanking mesophallus	Melanagromyza Hendel (in part)
–	Thorax without metallic sheen (Figs 44–48). Eye bare. Orbital plate bulging, forming prominent ring with parafacial. Mid tibia without posteromedial setae. Postsutural intra-alar setae approximately subequal. Epandrium without spine as below (Fig. 250). Phallophorus produced anteroventrally into a large pouch. Basiphallus asymmetrical. Distiphallus never with paired basal tubules	Euhexomyza Lonsdale
8	Lunule conspicuous, at least as high as pedicel, well-sclerotised and usually convex (even if partially concealed by pronounced orbital plates) (Figs 99–105); ranging from subcircular to long and narrow, but if shallower than a semicircle, lunule very large and broad (some Dizygomyza). Orbital setulae sometimes only reclinate in part, usually entirely erect to reclinate; vein dm-m always present. Distiphallus often long, robust and bifid (sometimes secondarily fused or more membranous) with apex usually swollen or bell-shaped (Figs 493, 494, 511, 512, 543, 544)	Cerodontha Rondani (9)
–	Lunule weakly sclerotised, slightly concave and usually shallow; if appearing higher than pedicel, then either orbital setulae entirely proclinate (Phytomyza and some Phytoliriomyza) or epandrium with rows of conspicuous tubercle-like setae (some Phytoliriomyza). Distiphallus various	15
9	First flagellomere pointed (Fig. 106) or angled anterodorsally. Scutellum with lateral scutellar setae absent (i.e., only one pair of setae present apically)	10
–	First flagellomere rounded anteriorly. Scutellum with two pairs of setae (some global Poemyza rarely with one pair, but lunule very high and narrow)	11
10	First flagellomere produced as a thin point anterodorsally (Fig. 106); point uncommonly reduced, some non-Nearctic species with point absent and segment simply angulate. Body with conspicuous yellow patches	C. (Cerodontha) Rondani
–	First flagellomere angulate anterodorsally. Body brown to black (Fig. 104)	C. (Xenophytomyza) Frey
11	Costa only extending to vein R4+5	C. (Phytagromyza) Hendel
–	Costa ending at vein M1	12
12	Prescutellar acrostichal seta present. Lunule slightly higher than wide, well-sclerotised, smooth, gradually tapering to a point dorsally, and light brown to brown with even covering of very short velvety pubescence (Fig. 99)	C. (Butomomyza) Nowakowski
–	Prescutellar acrostichal seta usually absent, but uncommonly weak to well-developed. If lunule higher than wide, then not as above. Lunule uncommonly approaching state as defined above, but if so (e.g., C. (D.) scirpivora Spencer), then lunule smoothly rounded above and male first flagellomere densely haired	13
13	Lunule narrow, either higher than wide or appearing higher than wide with sides obscured beneath prominent orbital plates (Figs 101, 102); surface often shiny and minutely textured	C. (Poemyza) Hendel
–	Lunule as wide, or wider than high; surface smooth with indistinct to prominent pubescence	14
14	Lunule flat or curved, meeting anterior margin of frons, well-sclerotised (Fig. 105). Head usually entirely grey to dark brown. Male first flagellomere often enlarged and sometimes with long, conspicuous hairs; antennal bases often distinctly separated	C. (Dizygomyza) Hendel
–	Lunule bulging, usually projecting higher than sunken anterior margin of frons, weakly sclerotised (Fig. 103). Lunule bright yellow with frons sometimes also yellow. Male first flagellomere not larger than those of females and with hairs moderately sized; antennal bases closely approximated	C. (Icteromyza) Hendel
15	Vein R4+5 as close, or closer to wing apex than vein M1 (Figs 689, 690). Lunule often silvery or with shiny pubescence (Fig. 124). Usually large and stout-bodied. Subepandrial sclerite stout, with halves broadly fused, and usually with single large spine (pronounced in Nemorimyza) (Figs 670, 684)	16
–	Vein M1 closer to wing tip than vein R4+5 (Figs 429, 693, 836). Lunule often bare or pubescent, rarely silvery. Usually small and slender-bodied. Subepandrial sclerite various, but u ncommonly as above	17
16	Fore tibia sometimes with posteromedial seta (Fig. 121); halter sometimes with dark spot. Surstylus with base elongate, strongly projecting dorsally into epandrium (Figs 662, 663). Basiphallus composed of two wide interlocking plates; apices flanking hypophallus narrow and curved (Figs 665, 666). Distiphallus stout, with abruptly widened base. Common Holarctic species (N.posticata (Meigen)) with male abdomen posterior to tergite 3 or 4 yellow	Nemorimyza Frey
–	Fore tibia rarely with posteromedial setae. Halter entirely white. Surstylus small, lobate (Figs 683–685). Male abdomen usually entirely dark, never as above. Basiphallus not as above; narrowed with halves fused basally to form a stalk (Fig. 681). Distiphallus usually narrower than above, at least towards base	Phytobia Lioy
17	Costa extending to vein M1 (Fig. 463)	18
–	Costa extending to vein R4+5, or slightly past (Fig. 435)	24
18	Two distinct dorsocentral setae, with anterior two pairs highly reduced and barely longer than surrounding setulae (few global species with three or four setae developed). Head and notopleuron pale yellow with antenna and most of remaining notum contrastingly dark (some exceptions outside of Nearctic) (Figs 90–98). Epandrium and surstylus each with dense clusters of tubercles (Figs 446–448)	Calycomyza Hendel
–	Three or more pronounced dorsocentral setae; if only two present, colour never as above. Arrangement of tubercles on epandrium usually much reduced (Figs 621, 626), arranged in rows (Fig. 710) or otherwise not as above (but see Liriomyzaquadrisetosa – Figs 616–620)	19
19	Halter white to entirely black, but never white with apical surface brownish. Distiphallus usually black, dense, and surrounded by minutely spinulose membrane (Figs 424, 426). Gena usually 1/3–1/2 height of eye (Fig. 87), but sometimes shallow (Fig. 85). Ejaculatory apodeme large, bowl-shaped sclerotisation on sperm pump (Fig. 418)	Amauromyza Hendel
–	Halter white, sometimes with apical surface of halter brown. Distiphallus without spinulose membrane. Gena usually < 1/3 eye height, uncommonly higher. Sperm pump uncommonly as above, usually with much smaller, ovate or band-like sclerotisation (Figs 464, 472, 531, 588) that may be vestigial to absent (Fig. 659)	20
20	Scutellum yellow centrally and orbital plate brown and slightly to conspicuously pronounced, contrasting with the weakly sclerotised central vitta (also usually brown). Broad, sclerotised ocellar triangle and orbital plates joined to form sharp angles with the outline of an “M”. Surstylus with at least one, and epandrium with two rows of tubercle-like setae (Figs 654–657)	Metopomyza Enderlein
–	If orbital plate dark brown as above, then not pronounced and scutellum entirely brown. If ocellar triangle and orbital plate joined along posterior margin of frons, then broadly joined by an intervening space (i.e., connecting angle broadly rounded or squared). Male genitalia infrequently as above (some Phytoliriomyza)	21
21	Apical surface of halter light brown (Fig. 127). Orbital setulae proclinate. Eye with minute ommatrichia. Side of frons with light silvery pubescence (Fig. 126). Scutellum entirely brown or yellowish medially	Phytoliriomyza Hendel (in part)
–	Halter entirely white. Orbital setulae upright to reclinate, sometimes absent; if proclinate (some Phytoliriomyza) then epandrium with dense row of tubercle-like setae. Eye bare or with few scattered ommatrichia. Side of frons not reflective as above. Scutellum usually distinctly yellow medially	22
22	With one of the following characters: frons with slight reflective pruinosity anterolaterally; orbital setulae proclinate; first flagellomere slightly elongate and black; scutellum and large portions of scutum matt grey; epandrium and surstylus with rows of tubercle-like setae (Fig. 705)	Phytoliriomyza Hendel (in part)
–	Frons never with reflective pruinosity. First flagellomere yellow to dark brown, never black. Scutellum usually subshiny to shiny (sometimes pruinose) and with central yellow stripe (sometimes reduced to absent). Epandrium and surstylus usually with one or two tubercle-like setae, but if with more, these never arranged in a discrete row	23
23	Vein dm-m often present (Fig. 652). Male abdomen sometimes with anterolateral stridulatory organ in membrane (Fig. 107). Phallus with at least two distinct sclerotised segments (Figs 593, 594). Apical section of ejaculatory duct pigmented and abruptly dilated	Liriomyza Mik
–	Vein dm-m often absent (Fig. 581). Male abdomen never with stridulatory organ as above. Phallus small and membranous with base sclerotised (Figs 579, 580). Apical section of ejaculatory duct clear and of equal width along length	Haplopeodes Steyskal
24	Orbital setulae proclinate (Fig. 133). Phallophorus often flanked by one pair of rod-like sclerites (Figs 803, 804)	Phytomyza Fallén s. l. (25)
–	Orbital setulae reclinate or upright (as in Fig. 2). Phallophorus without paired lateral sclerites	26
25	Vein dm-m present; usually in line with, or slightly basal to r-m, but sometimes slightly distal to r-m as below. Scutum mostly dark with grey pruinosity (Fig. 131). Distiphallus undivided apically, with apical sclerotised ring or tubule connected to dorsal sclerotisation on shaft	P. (Napomyza) Westwood
–	Vein dm-m usually absent; if present, then positioned slightly distal to r-m (Fig. 435). Scutum variably coloured and tomentose (Figs 132–138). Distiphallus usually divided apically; if undivided and with apical ring, then ring continuous with ventral sclerotisation along shaft	P. (Phytomyza) Fallén
26	Vein r-m basal to dm-m (Fig. 88); if dm-m absent, then r-m positioned far from vein bm-m and colouration bright yellow (Fig. 89). Vein M sclerotised far basal to vein r-m. First flagellomere rounded apically, sometimes with dorsomedial margin forming a slightly raised angle	Aulagromyza Enderlein
–	Vein dm-m and basal section of M absent, with r-m and bm-m nearly forming a straight transverse line (Fig. 833) [some Old World species with vein r-m distal to vein dm-m, with dm-m enclosing a very small cell between it and bm-m]. Colour always black (Fig. 130). First flagellomere with projecting anterodorsal angle [Old World species outside P.atra group with segment rounded]	Pseudonapomyza Hendel