British Hoverflies: the genera

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L. Watson and M. J. Dallwitz

Conventional key

If you are serious about identification, you should use the interactive key. It is far superior, with flexible choice of characters, character notes and illustrations, error tolerance, full taxon descriptions, and taxon illustrations.

1(0).
  • The humeri bare (often obscured by the appressed, deeply concave rear of the head) ... 2
  • The humeri hairy, and readily visible behind the head (the head well forward, not concave behind)... 63

2(1).
  • The flies 2-5 mm long ... 3
  • The flies 5-10 mm long... 7
  • The flies 10-15 mm long... 32
  • The flies 15-20 mm long... 62

3(2).
  • The eyes hairy ... 4
  • The eyes bare... 5

4(3).
  • The face ground-coloured at least part yellow; the upper and lower outer marginal cross veins strongly stepped; antennae with their bases approximated; the larvae flattened; the larvae not green ... Paragus
  • The face entirely dark in ground colour; the upper and lower outer marginal cross veins slightly stepped; antennae with their bases well separated; the larvae scarcely flattened; the larvae green ... Melanostoma

5(3).
  • The face ground-coloured at least part yellow; the thorax patterned; the larvae tapering anteriorly and posteriorly from the middle ... Sphaerophoria
  • The face entirely dark in ground colour; the thorax plain; the larvae broader posteriorly, tapered to the head... 6

6(5).
  • The front tibiae and/or tarsi dilated in males, broad and flattened in females; the metasternum entire, broad over its whole length ... Platycheirus
  • The front tibiae and/or tarsi simple; the metasternum reduced, the sclerotized part small with the central area diamond-shaped ... Melanostoma

7(2).
  • The thorax with longitudinal stripes ... 8
  • The thorax without longitudinal stripes... 13

8(7).
  • The eyes hairy ... 9
  • The eyes bare... 10

9(8).
  • The face ground-coloured at least part yellow; the lower outer marginal vein more or less parallel with the posterior wing margin; wings divergent in repose; the larvae not translucent ... Scaeva
  • The face entirely dark in ground colour; the lower outer marginal vein markedly diverging from the posterior wing margin; wings incumbent and almost parallel in repose; the larvae translucent ... Melanostoma

10(8).
  • The upper and lower outer marginal cross veins more or less continuous ... Epistrophe
  • The upper and lower outer marginal cross veins slightly stepped... 11
  • The upper and lower outer marginal cross veins strongly stepped... 12

11(10).
  • The face ground-coloured at least part yellow; the thorax patterned; the larvae tapering anteriorly and posteriorly from the middle; the larvae not translucent ... Sphaerophoria
  • The face entirely dark in ground colour; the thorax plain; the larvae broader posteriorly, tapered to the head; the larvae translucent ... Melanostoma

12(10).
  • The lateral margins of the tergites exhibiting beaded rims; the larvae not green ... Xanthogramma
  • The lateral margins of the tergites smoothly rolled over and without beading; the larvae green ... Sphaerophoria

13(7).
  • Vein R4+5 with a conspicuous curve projecting into the cell R5 ... 14
  • Vein R4+5 without a conspicuous curve projecting into the cell R5... 15

14(13).
  • Antennae relatively short, drooping (shorter than the head); the antennal bristle dorsal (proximal to sub-apical); the anterior cross vein R-M in cell R5 crossing it before the middle of the adjoining discal cell; vein R4+5 without a backwardly projecting, incomplete transverse veinlet; the face with a central knob (median prominence or tubercle) ... Eupeodes
  • Antennae relatively long, porrect (at least as long as the head); the antennal bristle apical, terminating the third segment; the anterior cross vein R-M in cell R5 crossing it at or beyond the middle of the adjoining discal cell; vein R4+5 with a short, backwardly projecting, incomplete transverse veinlet located distally to the cross veinlet in cell R5; the face without a central knob ... Ceriana

15(13).
  • The face ground-coloured at least part yellow ... 16
  • The face entirely dark in ground colour... 28

16(15).
  • The eyes hairy ... 17
  • The eyes bare... 22

17(16).
  • The lower outer marginal vein markedly diverging from the posterior wing margin ... Paragus
  • The lower outer marginal vein slightly diverging from the posterior wing margin... 18
  • The lower outer marginal vein more or less parallel with the posterior wing margin... 19

18(17).
  • The dorsum of tergite 2 exhibiting a wineglass-shaped black area; the anterior anepisternum at least partly pilose; the larvae tapering anteriorly and posteriorly from the middle; the larvae laterally smooth; the anal segments of the larvae without horn-like projections ... Parasyrphus
  • The dorsum of tergite 2 without a wineglass-shaped black area; the anterior anepisternum bare; the larvae broader posteriorly, tapered to the head; the larvae with conspicuous lateral projections; the anal segments of the larvae with a pair of curved, horn-like projections ... Dasysyrphus

19(17).
  • The upper outer marginal cross-vein gently curved or straightish; the thoracic squamae with long hairs on their dorsal surfaces ... Syrphus
  • The upper outer marginal cross-vein conspicuously bent near the base the base; the thoracic squamae without long hairs dorsally... 20

20(19).
  • Wings with a conspicuous dark stigma ... Leucozona
  • Wings without a conspicuously dark stigma... 21

21(20).
  • The abdomen wider than the thorax; wings divergent in repose; the anterior anepisternum bare; the larvae broader posteriorly, tapered to the head; the larvae scarcely flattened ... Scaeva
  • The abdomen about the same width as the thorax; wings incumbent and almost parallel in repose; the anterior anepisternum at least partly pilose; the larvae tapering anteriorly and posteriorly from the middle; the larvae flattened ... Parasyrphus

22(16).
  • Wings exhibiting tiny uniformly spaced black flecks along the hind edges ... Meliscaeva
  • Wings without black flecks along the hind edges... 23

23(22).
  • The thorax patterned ... Epistrophe
  • The thorax plain... 24

24(23).
  • The thoracic squamae with long hairs on their dorsal surfaces ... Syrphus
  • The thoracic squamae without long hairs dorsally... 25

25(24).
  • The lateral margins of the tergites exhibiting beaded rims ... 26
  • The lateral margins of the tergites smoothly rolled over and without beading... 27

26(25).
  • The anterior anepisternum at least partly pilose; the larvae tapering anteriorly and posteriorly from the middle; the larvae flattened ... Parasyrphus
  • The anterior anepisternum bare; the larvae broader posteriorly, tapered to the head; the larvae scarcely flattened ... Eupeodes

27(25).
  • The anterior anepisternum at least partly pilose; the larvae tapering anteriorly and posteriorly from the middle ... Parasyrphus
  • The anterior anepisternum bare; the larvae broader posteriorly, tapered to the head ... Meligramma

28(15).
  • Wings with a conspicuous dark stigma ... 29
  • Wings without a conspicuously dark stigma... 30

29(28).
  • The alula distinct; the abdomen wider than the thorax; the abdomen not petiolated; antennae with their bases well separated; the larvae green ... Xanthandrus
  • The alula indistinct; the abdomen narrower than the thorax; the abdomen proximally petiolated; antennae with their bases approximated; the larvae not green ... Baccha

30(28).
  • The metasternum entire, broad over its whole length ... 31
  • The metasternum reduced, the sclerotized part small with the central area diamond-shaped ... Melanostoma

31(30).
  • The lower outer marginal vein markedly diverging from the posterior wing margin ... Platycheirus
  • The lower outer marginal vein slightly diverging from the posterior wing margin ... Platycheirus
  • The lower outer marginal vein more or less parallel with the posterior wing margin ... Melangyna

32(2).
  • Antennae relatively short, drooping (shorter than the head) ... 33
  • Antennae relatively long, porrect (at least as long as the head)... 61

33(32).
  • The thorax with longitudinal stripes ... 34
  • The thorax without longitudinal stripes... 39

34(33).
  • The eyes hairy ... Scaeva
  • The eyes bare... 35

35(34).
  • The thorax patterned; wings without black flecks along the hind edges; the anterior anepisternum bare; the larvae not translucent ... 36
  • The thorax plain; wings exhibiting tiny uniformly spaced black flecks along the hind edges; the anterior anepisternum at least partly pilose; the larvae translucent ... Episyrphus

36(35).
  • The upper and lower outer marginal cross veins more or less continuous ... Epistrophe
  • The upper and lower outer marginal cross veins slightly stepped ... Sphaerophoria
  • The upper and lower outer marginal cross veins strongly stepped... 37

37(36).
  • The lateral margins of the tergites exhibiting beaded rims ... Xanthogramma
  • The lateral margins of the tergites smoothly rolled over and without beading... 38

38(37).
  • Wings patterned; the larvae not green ... Doros
  • Wings plain; the larvae green ... Sphaerophoria

39(33).
  • Vein R4+5 with a conspicuous curve projecting into the cell R5 ... 40
  • Vein R4+5 without a conspicuous curve projecting into the cell R5... 43

40(39).
  • Wings with a conspicuous dark stigma ... 41
  • Wings without a conspicuously dark stigma... 42

41(40).
  • The scutellum at least partly yellow ... Didea
  • The scutellum brownish, ferrugineous or tawny ... Didea
  • The scutellum whitish ... Eriozona

42(40).
  • The scutellum aeneous ... Eupeodes
  • The scutellum brownish, ferrugineous or tawny ... Eupeodes
  • The scutellum black ... Eupeodes
  • The scutellum whitish ... Eriozona

43(39).
  • The face ground-coloured at least part yellow ... 44
  • The face entirely dark in ground colour... 58

44(43).
  • The eyes hairy ... 45
  • The eyes bare... 51

45(44).
  • The upper outer marginal cross-vein gently curved or straightish; the thoracic squamae with long hairs on their dorsal surfaces ... Syrphus
  • The upper outer marginal cross-vein conspicuously bent near the base the base; the thoracic squamae without long hairs dorsally... 46

46(45).
  • Wings with a conspicuous dark stigma ... 47
  • Wings without a conspicuously dark stigma... 48

47(46).
  • The lower outer marginal vein slightly diverging from the posterior wing margin; the lateral margins of the tergites exhibiting beaded rims; the larvae not translucent; the larvae with conspicuous lateral projections; the anal segments of the larvae with a pair of curved, horn-like projections ... Dasysyrphus
  • The lower outer marginal vein more or less parallel with the posterior wing margin; the lateral margins of the tergites smoothly rolled over and without beading; the larvae translucent; the larvae laterally smooth; the anal segments of the larvae without horn-like projections ... Leucozona

48(46).
  • The lower outer marginal vein slightly diverging from the posterior wing margin ... 49
  • The lower outer marginal vein more or less parallel with the posterior wing margin... 50

49(48).
  • The dorsum of tergite 2 exhibiting a wineglass-shaped black area; the anterior anepisternum at least partly pilose; the larvae tapering anteriorly and posteriorly from the middle; the larvae laterally smooth; the anal segments of the larvae without horn-like projections ... Parasyrphus
  • The dorsum of tergite 2 without a wineglass-shaped black area; the anterior anepisternum bare; the larvae broader posteriorly, tapered to the head; the larvae with conspicuous lateral projections; the anal segments of the larvae with a pair of curved, horn-like projections ... Dasysyrphus

50(48).
  • The abdomen wider than the thorax; wings divergent in repose; the anterior anepisternum bare; the larvae broader posteriorly, tapered to the head; the larvae scarcely flattened ... Scaeva
  • The abdomen about the same width as the thorax; wings incumbent and almost parallel in repose; the anterior anepisternum at least partly pilose; the larvae tapering anteriorly and posteriorly from the middle; the larvae flattened ... Parasyrphus

51(44).
  • Wings exhibiting tiny uniformly spaced black flecks along the hind edges ... 52
  • Wings without black flecks along the hind edges... 53

52(51).
  • The scutellum at least partly yellow; the lower outer marginal vein slightly diverging from the posterior wing margin; wings incumbent and almost parallel in repose; the flies sphecid wasp-like; the larvae not green ... Meliscaeva
  • The scutellum brownish, ferrugineous or tawny; the lower outer marginal vein more or less parallel with the posterior wing margin; wings divergent in repose; the flies Nomada-like; the larvae green ... Episyrphus

53(51).
  • The thorax patterned ... Epistrophe
  • The thorax plain... 54

54(53).
  • The upper outer marginal cross-vein gently curved or straightish; the thoracic squamae with long hairs on their dorsal surfaces ... Syrphus
  • The upper outer marginal cross-vein conspicuously bent near the base the base; the thoracic squamae without long hairs dorsally... 55

55(54).
  • The dorsum of tergite 2 exhibiting a wineglass-shaped black area ... 56
  • The dorsum of tergite 2 without a wineglass-shaped black area... 57

56(55).
  • The anterior anepisternum at least partly pilose; the larvae tapering anteriorly and posteriorly from the middle; the larvae flattened ... Parasyrphus
  • The anterior anepisternum bare; the larvae broader posteriorly, tapered to the head; the larvae scarcely flattened ... Eupeodes

57(55).
  • The scutellum aeneous ... Eupeodes
  • The scutellum brownish, ferrugineous or tawny ... Eupeodes
  • The scutellum black ... Eupeodes
  • The scutellum whitish ... Eriozona

58(43).
  • Wings with a conspicuous dark stigma ... 59
  • Wings without a conspicuously dark stigma... 60

59(58).
  • The alula distinct; the abdomen wider than the thorax; the abdomen not petiolated; antennae with their bases well separated; the larvae green ... Xanthandrus
  • The alula indistinct; the abdomen narrower than the thorax; the abdomen proximally petiolated; antennae with their bases approximated; the larvae not green ... Baccha

60(58).
  • The lower outer marginal vein markedly diverging from the posterior wing margin ... Platycheirus
  • The lower outer marginal vein slightly diverging from the posterior wing margin ... Platycheirus
  • The lower outer marginal vein more or less parallel with the posterior wing margin ... Melangyna

61(32).
  • The thorax with longitudinal stripes; the antennal bristle dorsal (proximal to sub-apical); the anterior cross vein R-M in cell R5 crossing it before the middle of the adjoining discal cell; vein R4+5 without a backwardly projecting, incomplete transverse veinlet; wings incumbent and almost parallel in repose ... Chrysotoxum
  • The thorax without longitudinal stripes; the antennal bristle apical, terminating the third segment; the anterior cross vein R-M in cell R5 crossing it at or beyond the middle of the adjoining discal cell; vein R4+5 with a short, backwardly projecting, incomplete transverse veinlet located distally to the cross veinlet in cell R5; wings divergent in repose ... Ceriana

62(2).
  • The thorax with longitudinal stripes; the head about the same width as the thorax; the thorax patterned; wings patterned; the lateral margins of the tergites smoothly rolled over and without beading ... Doros
  • The thorax without longitudinal stripes; the head wider than the thorax; the thorax plain; wings plain; the lateral margins of the tergites exhibiting beaded rims ... Eriozona

63(1).
  • Vein R4+5 with a conspicuous curve projecting into the cell R5 ... 64
  • Vein R4+5 without a conspicuous curve projecting into the cell R5... 83

64(63).
  • The flies 5-10 mm long ... 65
  • The flies 10-15 mm long... 71
  • The flies 15-20 mm long... 81

65(64).
  • The eyes hairy ... 66
  • The eyes bare... 69

66(65).
  • Antennae relatively short, drooping (shorter than the head); the antennal bristle dorsal (proximal to sub-apical); vein R4+5 without a backwardly projecting, incomplete transverse veinlet; the lower outer marginal vein more or less parallel with the posterior wing margin ... 67
  • Antennae relatively long, porrect (at least as long as the head); the antennal bristle apical, terminating the third segment; vein R4+5 with a short, backwardly projecting, incomplete transverse veinlet located distally to the cross veinlet in cell R5; the lower outer marginal vein slightly diverging from the posterior wing margin ... Ceriana

67(66).
  • The thorax black with pale longitudinal and transverse markings which produce a skull-like figure ... Myathropa
  • The thorax not exhibiting a skull-like figure... 68

68(67).
  • The hind femur with a large triangular plate at its distal end; the thorax shaggy with soft hair; wings incumbent and almost parallel in repose; the larvae posteriorly blunt and tail-less; the anal segment of the larva shorter than the rest of the body ... Merodon
  • The hind femur distally with neither a triangular plate nor a tooth; the thorax pubescent without stiff bristles interspersed (not shaggy); wings divergent in repose; the larvae tailed; the anal segment of the larva at least as long as the rest of the body ... Eristalinus

69(65).
  • Antennae relatively short, drooping (shorter than the head); the antennal bristle dorsal (proximal to sub-apical); vein R4+5 without a backwardly projecting, incomplete transverse veinlet; the lower outer marginal vein more or less parallel with the posterior wing margin; the scutellum brownish, ferrugineous or tawny ... 70
  • Antennae relatively long, porrect (at least as long as the head); the antennal bristle apical, terminating the third segment; vein R4+5 with a short, backwardly projecting, incomplete transverse veinlet located distally to the cross veinlet in cell R5; the lower outer marginal vein slightly diverging from the posterior wing margin; the scutellum at least partly yellow ... Ceriana

70(69).
  • The thorax black with pale longitudinal and transverse markings which produce a skull-like figure; the tergite bands much less wide than the segments; wings divergent in repose ... Anasimyia
  • The thorax not exhibiting a skull-like figure; the tergite bands almost as wide as the segments; wings incumbent and almost parallel in repose ... Parhelophilus

71(64).
  • The eyes hairy ... 72
  • The eyes bare... 77

72(71).
  • Antennae relatively short, drooping (shorter than the head); the antennal bristle dorsal (proximal to sub-apical); vein R4+5 without a backwardly projecting, incomplete transverse veinlet; the lower outer marginal vein more or less parallel with the posterior wing margin ... 73
  • Antennae relatively long, porrect (at least as long as the head); the antennal bristle apical, terminating the third segment; vein R4+5 with a short, backwardly projecting, incomplete transverse veinlet located distally to the cross veinlet in cell R5; the lower outer marginal vein slightly diverging from the posterior wing margin ... Ceriana

73(72).
  • The abdomen conspicuously furry ... 74
  • The abdomen not conspicuously furry (short-haired to more or less hairless)... 75

74(73).
  • Wing veins R2+3 and R4+5 forming a closed cell; the upper outer marginal cross-vein not re-entrant; the hind femur distally with neither a triangular plate nor a tooth; the thorax pubescent without stiff bristles interspersed (not shaggy); the larvae tailed ... Eristalis
  • Wing veins R2+3 and R4+5 not forming a closed cell, but ending separately at the margin; the upper outer marginal cross-vein re-entrant; the hind femur with a large triangular plate at its distal end; the thorax shaggy with soft hair; the larvae posteriorly blunt and tail-less ... Merodon

75(73).
  • The thorax black with pale longitudinal and transverse markings which produce a skull-like figure ... Myathropa
  • The thorax not exhibiting a skull-like figure... 76

76(75).
  • The hind femur with a large triangular plate at its distal end; the thorax shaggy with soft hair; wings incumbent and almost parallel in repose; the larvae posteriorly blunt and tail-less; the anal segment of the larva shorter than the rest of the body ... Merodon
  • The hind femur distally with neither a triangular plate nor a tooth; the thorax pubescent without stiff bristles interspersed (not shaggy); wings divergent in repose; the larvae tailed; the anal segment of the larva at least as long as the rest of the body ... Eristalinus

77(71).
  • The tergite patterning comprising pale, straight, obliquely longitudinal markings on either side ... Lejops
  • The tergite patterning not comprising obliquely longitudial marks... 78

78(77).
  • Antennae relatively short, drooping (shorter than the head); the antennal bristle dorsal (proximal to sub-apical); the scutellum brownish, ferrugineous or tawny; vein R4+5 without a backwardly projecting, incomplete transverse veinlet; the lower outer marginal vein more or less parallel with the posterior wing margin ... 79
  • Antennae relatively long, porrect (at least as long as the head); the antennal bristle apical, terminating the third segment; the scutellum at least partly yellow; vein R4+5 with a short, backwardly projecting, incomplete transverse veinlet located distally to the cross veinlet in cell R5; the lower outer marginal vein slightly diverging from the posterior wing margin ... Ceriana

79(78).
  • The thorax black with pale longitudinal and transverse markings which produce a skull-like figure; the tergite bands much less wide than the segments ... Anasimyia
  • The thorax not exhibiting a skull-like figure; the tergite bands almost as wide as the segments... 80

80(79).
  • Wings with a conspicuous dark stigma ... Parhelophilus
  • Wings without a conspicuously dark stigma ... Helophilus

81(64).
  • The eyes hairy; the abdomen conspicuously furry; wing veins R2+3 and R4+5 forming a closed cell ... Eristalis
  • The eyes bare; the abdomen not conspicuously furry (short-haired to more or less hairless); wing veins R2+3 and R4+5 not forming a closed cell, but ending separately at the margin... 82

82(81).
  • The thorax with longitudinal stripes; the abdomen contrastingly patterned; the thorax patterned; the flies vespid wasp-like ... Helophilus
  • The thorax without longitudinal stripes; the abdomen not contrastingly patterned; the thorax plain; the flies hivebee-like ... Mallota

83(63).
  • The flies 2-5 mm long ... 84
  • The flies 5-10 mm long... 100
  • The flies 10-15 mm long... 149
  • The flies 15-20 mm long... 172

84(83).
  • The anterior cross vein R-M in cell R5 crossing it before the middle of the adjoining discal cell ... 85
  • The anterior cross vein R-M in cell R5 crossing it at or beyond the middle of the adjoining discal cell... 99

85(84).
  • The abdomen contrastingly patterned ... 86
  • The abdomen not contrastingly patterned... 90

86(85).
  • The tergite patterning confined to tergite 2; the upper outer marginal cross-vein conspicuously bent near the base the base; the larvae translucent ... Trichopsomyia
  • The tergite patterning not confined to one tergite; the upper outer marginal cross-vein conspicuously bent well above the base; the larvae not translucent... 87

87(86).
  • The third (bistle-bearing) antennal segment ovoid or orbicular ... 88
  • The third (bistle-bearing) antennal segment almost semicircular, with the upper edge straight and the arista near the apex ... Pelecocera

88(87).
  • The tergite bands much less wide than the segments ... Neoascia
  • The tergite bands almost as wide as the segments... 89

89(88).
  • The abdomen proximally petiolated; wings incumbent and almost parallel in repose ... Sphegina
  • The abdomen not petiolated; wings divergent in repose ... Chamaesyrphus

90(85).
  • The antennal bristle apical, terminating the third segment; the antennal bristle plumose; the larvae with conspicuous lateral projections ... Hammerschmidtia
  • The antennal bristle dorsal (proximal to sub-apical); the antennal bristle simple (bare, or no more than shortly hairy); the larvae laterally smooth... 91

91(90).
  • The eyes hairy ... 92
  • The eyes bare... 95

92(91).
  • Wings with a conspicuous dark stigma; the larvae tailed; the larvae saprophagous; the larvae aquatic ... Orthonevra
  • Wings without a conspicuously dark stigma; the larvae posteriorly blunt and tail-less; the larvae predatory; the larvae non-aquatic... 93

93(92).
  • The abdomen dominated by the large tergites 2 and 3, tergite 4 being minute or not visible ... Triglyphus
  • The abdomen with tergites 2, 3 and 4 all more or less well developed and equal in length... 94

94(93).
  • The upper outer marginal cross-vein strongly angled to vein R4+5, so that cell R5 is markedly extended towards the wing tip; the larvae not translucent ... Heringia
  • The upper outer marginal cross-vein joining vein R4+5 almost at right angles, so that cell R5 is not extended towards the wing tip; the larvae translucent ... Trichopsomyia

95(91).
  • The upper outer marginal cross-vein conspicuously bent near the base the base ... 96
  • The upper outer marginal cross-vein conspicuously bent well above the base... 98

96(95).
  • The abdomen dominated by the large tergites 2 and 3, tergite 4 being minute or not visible; the larvae posteriorly blunt and tail-less; the larvae flattened; the larvae non-aquatic ... Triglyphus
  • The abdomen with tergites 2, 3 and 4 all more or less well developed and equal in length; the larvae tailed; the larvae scarcely flattened; the larvae aquatic... 97

97(96).
  • Tergites 2-4 equally shiny-metallic all over, without dull patches; the face without tubercles; the frons not inflated; wings divergent in repose ... Lejogaster
  • Tergites 2-4 dulled at least dorsally; the face with tubercles; the frons markedly inflated; wings incumbent and almost parallel in repose ... Melanogaster

98(95).
  • Wings with a conspicuous dark stigma; the abdomen not petiolated; the upper outer marginal cross-vein bent at a sharp angle; the larvae scarcely flattened; the larvae aquatic ... Orthonevra
  • Wings without a conspicuously dark stigma; the abdomen proximally petiolated; the upper outer marginal cross-vein curved on the bend; the larvae flattened; the larvae non-aquatic ... Sphegina

99(84).
  • The lower outer marginal vein markedly diverging from the posterior wing margin; the upper outer marginal cross-vein re-entrant; the face neither keeled nor impressed; the larvae tapering anteriorly and posteriorly from the middle; the larvae posteriorly blunt and tail-less ... Eumerus
  • The lower outer marginal vein more or less parallel with the posterior wing margin; the upper outer marginal cross-vein not re-entrant; the face impressed; the larvae tapering posteriorly; the larvae tailed ... Brachypalpus

100(83).
  • The anterior cross vein R-M in cell R5 crossing it before the middle of the adjoining discal cell ... 101
  • The anterior cross vein R-M in cell R5 crossing it at or beyond the middle of the adjoining discal cell... 139

101(100).
  • Wings with a vena spuria ... 102
  • Wings apparently without a vena spuria... 138

102(101).
  • Antennae relatively short, drooping (shorter than the head) ... 103
  • Antennae relatively long, porrect (at least as long as the head)... 137

103(102).
  • The abdomen contrastingly patterned ... 104
  • The abdomen not contrastingly patterned... 114

104(103).
  • The upper outer marginal cross-vein gently curved or straightish ... 105
  • The upper outer marginal cross-vein conspicuously bent near the base the base... 107
  • The upper outer marginal cross-vein conspicuously bent well above the base... 111

105(104).
  • The thorax with longitudinal stripes; the thorax patterned; the face flat or concave in the region between the antennae and the mouth ... Syritta
  • The thorax without longitudinal stripes; the thorax plain; the face not flat or retreating between antennae and mouth (with a central knob, or arched, or produced cone-like elswhere than at the upper mouth edge)... 106

106(105).
  • The eyes rimmed along their facial borders for much of the height of the face; wings incumbent and almost parallel in repose; the larvae posteriorly blunt and tail-less; the larvae flattened ... Cheilosia
  • The eyes not rimmed along their facial borders for much of the height of the face; wings divergent in repose; the larvae tailed; the larvae scarcely flattened ... Myolepta

107(104).
  • The tergite patterning confined to tergite 2; the eyes not rimmed along their facial borders for much of the height of the face; the mouth with a triangular sclerite on either side; the anal segments of the larvae without lappets ... 108
  • The tergite patterning not confined to one tergite; the eyes rimmed along their facial borders for much of the height of the face; the mouth without triangular sclerites; the anal segments of the larvae with lappets... 109

108(107).
  • The upper outer marginal cross-vein strongly angled to vein R4+5, so that cell R5 is markedly extended towards the wing tip; wings incumbent and almost parallel in repose; the larvae not translucent ... Pipiza
  • The upper outer marginal cross-vein joining vein R4+5 almost at right angles, so that cell R5 is not extended towards the wing tip; wings divergent in repose; the larvae translucent ... Trichopsomyia

109(107).
  • The face drawn out into a horizontal cone as long as the rest of the head; antennae with their bases approximated ... Rhingia
  • The face not elongated horizontally into a cone as long as the rest of the head; antennae with their bases well separated... 110

110(109).
  • The face with a central knob (median prominence or tubercle) ... Cheilosia
  • The face without a central knob ... Portevinia

111(104).
  • The third (bistle-bearing) antennal segment ovoid or orbicular ... 112
  • The third (bistle-bearing) antennal segment almost semicircular, with the upper edge straight and the arista near the apex ... Pelecocera

112(111).
  • The tergite bands much less wide than the segments ... Neoascia
  • The tergite bands almost as wide as the segments... 113

113(112).
  • The abdomen proximally petiolated; wings incumbent and almost parallel in repose ... Sphegina
  • The abdomen not petiolated; wings divergent in repose ... Chamaesyrphus

114(103).
  • The eyes hairy ... 115
  • The eyes bare... 124

115(114).
  • The thorax with longitudinal stripes ... 116
  • The thorax without longitudinal stripes... 117

116(115).
  • The eyes rimmed along their facial borders for much of the height of the face; wings without a conspicuously dark stigma; the upper and lower outer marginal cross veins slightly stepped; the upper outer marginal cross-vein conspicuously bent near the base the base; antennae with their bases approximated ... Ferdinandea
  • The eyes not rimmed along their facial borders for much of the height of the face; wings with a conspicuous dark stigma; the upper and lower outer marginal cross veins strongly stepped; the upper outer marginal cross-vein conspicuously bent well above the base; antennae with their bases well separated ... Orthonevra

117(115).
  • The abdomen dominated by the large tergites 2 and 3, tergite 4 being minute or not visible ... Triglyphus
  • The abdomen with tergites 2, 3 and 4 all more or less well developed and equal in length... 118

118(117).
  • The face with a central knob (median prominence or tubercle); the eyes rimmed along their facial borders for much of the height of the face ... Cheilosia
  • The face without a central knob; the eyes not rimmed along their facial borders for much of the height of the face... 119

119(118).
  • The upper outer marginal cross-vein strongly angled to vein R4+5, so that cell R5 is markedly extended towards the wing tip ... 120
  • The upper outer marginal cross-vein joining vein R4+5 almost at right angles, so that cell R5 is not extended towards the wing tip... 122

120(119).
  • The upper outer marginal cross-vein gently curved or straightish ... Heringia
  • The upper outer marginal cross-vein conspicuously bent near the base the base... 121
  • The upper outer marginal cross-vein conspicuously bent well above the base ... Orthonevra

121(120).
  • The hypopleuron exhibiting long hairs on its upper transverse ridge ... Heringia
  • The hypopleuron with no long hairs on its upper transverse ridge ... Pipiza

122(119).
  • Wings with a conspicuous dark stigma; the larvae tailed; the mouth without triangular sclerites; the anal segments of the larvae with lappets; the larvae aquatic ... Orthonevra
  • Wings without a conspicuously dark stigma; the larvae posteriorly blunt and tail-less; the mouth with a triangular sclerite on either side; the anal segments of the larvae without lappets; the larvae non-aquatic... 123

123(122).
  • Wings divergent in repose; the larvae translucent; the larvae plain ... Trichopsomyia
  • Wings incumbent and almost parallel in repose; the larvae not translucent; the larvae patterned ... Pipizella

124(114).
  • The antennal bristle apical, terminating the third segment; the antennal bristle plumose ... Hammerschmidtia
  • The antennal bristle dorsal (proximal to sub-apical); the antennal bristle simple (bare, or no more than shortly hairy)... 125

125(124).
  • The face drawn out into a horizontal cone as long as the rest of the head ... Rhingia
  • The face not elongated horizontally into a cone as long as the rest of the head... 126

126(125).
  • The upper outer marginal cross-vein gently curved or straightish ... Cheilosia
  • The upper outer marginal cross-vein conspicuously bent near the base the base... 127
  • The upper outer marginal cross-vein conspicuously bent well above the base... 133

127(126).
  • The abdomen dominated by the large tergites 2 and 3, tergite 4 being minute or not visible ... Triglyphus
  • The abdomen with tergites 2, 3 and 4 all more or less well developed and equal in length... 128

128(127).
  • Tergites 2-4 equally shiny-metallic all over, without dull patches ... 129
  • Tergites 2-4 dulled at least dorsally... 130

129(128).
  • The face with a central knob (median prominence or tubercle); the eyes rimmed along their facial borders for much of the height of the face; wings incumbent and almost parallel in repose; the face not flat or retreating between antennae and mouth (with a central knob, or arched, or produced cone-like elswhere than at the upper mouth edge); the larvae posteriorly blunt and tail-less ... Cheilosia
  • The face without a central knob; the eyes not rimmed along their facial borders for much of the height of the face; wings divergent in repose; the face flat or concave in the region between the antennae and the mouth; the larvae tailed ... Lejogaster

130(128).
  • The frons markedly inflated ... 131
  • The frons not inflated... 132

131(130).
  • Antennae black; wings incumbent and almost parallel in repose; the face flat or concave in the region between the antennae and the mouth ... Melanogaster
  • Antennae ferruginous; wings divergent in repose; the face not flat or retreating between antennae and mouth (with a central knob, or arched, or produced cone-like elswhere than at the upper mouth edge) ... Chrysogaster

132(130).
  • The abdomen oval ... Riponnensia
  • The abdomen ovate (distally broadened) ... Riponnensia
  • The abdomen oblong ... Chrysogaster
  • The abdomen obovate (distally narrowed) ... Chrysogaster

133(126).
  • The upper outer marginal cross-vein bent at a sharp angle; the abdomen not petiolated ... 134
  • The upper outer marginal cross-vein curved on the bend; the abdomen proximally petiolated ... Sphegina

134(133).
  • Wings with a conspicuous dark stigma ... 135
  • Wings without a conspicuously dark stigma... 136

135(134).
  • The abdomen oval ... Orthonevra
  • The abdomen ovate (distally broadened) ... Orthonevra
  • The abdomen oblong ... Orthonevra
  • The abdomen obovate (distally narrowed) ... Brachyopa

136(134).
  • The abdomen oval ... Riponnensia
  • The abdomen ovate (distally broadened) ... Riponnensia
  • The abdomen obovate (distally narrowed) ... Brachyopa

137(102).
  • The eyes hairy; the antennal bristle apical, terminating the third segment; the head wider than the thorax; vein R4+5 without a backwardly projecting, incomplete transverse veinlet; the upper outer marginal cross-vein not re-entrant ... Callicera
  • The eyes bare; the antennal bristle dorsal (proximal to sub-apical); the head about the same width as the thorax; vein R4+5 with a short, backwardly projecting, incomplete transverse veinlet located distally to the cross veinlet in cell R5; the upper outer marginal cross-vein re-entrant ... Microdon

138(101).
  • The eyes hairy; the upper outer marginal cross-vein conspicuously bent well above the base; antennae black; antennae with their bases approximated; the face flat or concave in the region between the antennae and the mouth ... Psilota
  • The eyes bare; the upper outer marginal cross-vein conspicuously bent near the base the base; antennae ferruginous; antennae with their bases well separated; the face not flat or retreating between antennae and mouth (with a central knob, or arched, or produced cone-like elswhere than at the upper mouth edge) ... Chrysogaster

139(100).
  • The abdomen contrastingly patterned ... 140
  • The abdomen not contrastingly patterned... 145

140(139).
  • The abdomen conspicuously furry ... Blera
  • The abdomen not conspicuously furry (short-haired to more or less hairless)... 141

141(140).
  • The upper outer marginal cross-vein gently curved or straightish ... 142
  • The upper outer marginal cross-vein conspicuously bent near the base the base... 143
  • The upper outer marginal cross-vein conspicuously bent well above the base ... Eumerus

142(141).
  • The thorax with longitudinal stripes; the thorax patterned; the lower outer marginal vein markedly diverging from the posterior wing margin; the upper and lower outer marginal cross veins strongly stepped; the abdomen narrower than the thorax ... Syritta
  • The thorax without longitudinal stripes; the thorax plain; the lower outer marginal vein more or less parallel with the posterior wing margin; the upper and lower outer marginal cross veins more or less continuous; the abdomen about the same width as the thorax ... Tropidia

143(141).
  • The upper outer marginal cross-vein re-entrant; the face neither keeled nor impressed ... Eumerus
  • The upper outer marginal cross-vein not re-entrant; the face impressed... 144

144(143).
  • The abdomen about 4 to 5.7; the larvae flattened; the larvae with hooks on the thorax ... Chalcosyrphus
  • The abdomen about 5.8 to 7.8; the larvae scarcely flattened; the larvae without thoracic hooks ... Xylota

145(139).
  • The eyes hairy ... 146
  • The eyes bare... 147

146(145).
  • The thorax with longitudinal stripes; the thorax patterned; the eyes rimmed along their facial borders for much of the height of the face; the thorax pubescent with stiff bristles interspersed; the larvae broader posteriorly, tapered to the head ... Ferdinandea
  • The thorax without longitudinal stripes; the thorax plain; the eyes not rimmed along their facial borders for much of the height of the face; the thorax shaggy with soft hair; the larvae tapering posteriorly ... Brachypalpus

147(145).
  • The upper outer marginal cross-vein re-entrant; the larvae tapering anteriorly and posteriorly from the middle; the larvae posteriorly blunt and tail-less; the larvae phytophagous ... Eumerus
  • The upper outer marginal cross-vein not re-entrant; the larvae tapering posteriorly; the larvae tailed; the larvae saprophagous... 148

148(147).
  • The scutellum somewhat convex, with undefined edge; the lower outer marginal vein more or less parallel with the posterior wing margin; antennae with their bases approximated; the thorax shaggy with soft hair; the larvae flattened ... Brachypalpus
  • The scutellum flat, with a well defined edge; the lower outer marginal vein markedly diverging from the posterior wing margin; antennae with their bases well separated; the thorax pubescent without stiff bristles interspersed (not shaggy); the larvae scarcely flattened ... Riponnensia

149(83).
  • The antennal bristle simple (bare, or no more than shortly hairy) ... 150
  • The antennal bristle plumose... 169

150(149).
  • The anterior cross vein R-M in cell R5 crossing it before the middle of the adjoining discal cell ... 151
  • The anterior cross vein R-M in cell R5 crossing it at or beyond the middle of the adjoining discal cell... 157

151(150).
  • Antennae relatively short, drooping (shorter than the head) ... 152
  • Antennae relatively long, porrect (at least as long as the head)... 156

152(151).
  • The thorax with longitudinal stripes; the thorax patterned ... Ferdinandea
  • The thorax without longitudinal stripes; the thorax plain... 153

153(152).
  • The eyes rimmed along their facial borders for much of the height of the face ... Cheilosia
  • The eyes not rimmed along their facial borders for much of the height of the face... 154

154(153).
  • The upper outer marginal cross-vein gently curved or straightish; the face not flat or retreating between antennae and mouth (with a central knob, or arched, or produced cone-like elswhere than at the upper mouth edge); wings divergent in repose ... Myolepta
  • The upper outer marginal cross-vein conspicuously bent near the base the base; the face flat or concave in the region between the antennae and the mouth; wings incumbent and almost parallel in repose... 155

155(154).
  • The lower outer marginal vein markedly diverging from the posterior wing margin; the larvae posteriorly blunt and tail-less; the mouth with a triangular sclerite on either side; the anal segments of the larvae without lappets; the larvae predatory ... Pipiza
  • The lower outer marginal vein more or less parallel with the posterior wing margin; the larvae tailed; the mouth without triangular sclerites; the anal segments of the larvae with lappets; the larvae saprophagous ... Brachypalpoides

156(151).
  • The eyes hairy; the antennal bristle apical, terminating the third segment; the head wider than the thorax; vein R4+5 without a backwardly projecting, incomplete transverse veinlet; the upper outer marginal cross-vein not re-entrant ... Callicera
  • The eyes bare; the antennal bristle dorsal (proximal to sub-apical); the head about the same width as the thorax; vein R4+5 with a short, backwardly projecting, incomplete transverse veinlet located distally to the cross veinlet in cell R5; the upper outer marginal cross-vein re-entrant ... Microdon

157(150).
  • The abdomen conspicuously furry ... 158
  • The abdomen not conspicuously furry (short-haired to more or less hairless)... 161

158(157).
  • The upper outer marginal cross-vein gently curved or straightish ... Criorhina
  • The upper outer marginal cross-vein conspicuously bent near the base the base... 159

159(158).
  • The head wider than the thorax ... Caliprobola
  • The head about the same width as the thorax... 160
  • The head less wide than the thorax ... Pocota

160(159).
  • The scutellum somewhat convex, with undefined edge; wings divergent in repose; the larvae tapering posteriorly ... Caliprobola
  • The scutellum flat, with a well defined edge; wings incumbent and almost parallel in repose; the larvae broader posteriorly, tapered to the head ... Blera

161(157).
  • The abdomen contrastingly patterned ... 162
  • The abdomen not contrastingly patterned... 167

162(161).
  • The upper and lower outer marginal cross veins more or less continuous ... 163
  • The upper and lower outer marginal cross veins slightly stepped ... Brachypalpoides
  • The upper and lower outer marginal cross veins strongly stepped... 164

163(162).
  • The upper outer marginal cross-vein gently curved or straightish; the face longitudinally keeled; the larvae tapering posteriorly; the colour-patterned tergites marked with tawny to orange-ish; the larvae in decaying vegetation ... Tropidia
  • The upper outer marginal cross-vein conspicuously bent near the base the base; the face impressed; the larvae broader posteriorly, tapered to the head; the colour-patterned tergites marked with red; the larvae in rotten wood ... Brachypalpoides

164(162).
  • The upper outer marginal cross-vein re-entrant ... Eumerus
  • The upper outer marginal cross-vein not re-entrant... 165

165(164).
  • The scutellum somewhat convex, with undefined edge; the face ground-coloured at least part yellow ... Caliprobola
  • The scutellum flat, with a well defined edge; the face entirely dark in ground colour... 166

166(165).
  • The abdomen about 4 to 5.7; the larvae flattened; the larvae with hooks on the thorax ... Chalcosyrphus
  • The abdomen about 5.8 to 7.8; the larvae scarcely flattened; the larvae without thoracic hooks ... Xylota

167(161).
  • The eyes rimmed along their facial borders for much of the height of the face ... Ferdinandea
  • The eyes not rimmed along their facial borders for much of the height of the face... 168

168(167).
  • The lower outer marginal vein markedly diverging from the posterior wing margin; the upper outer marginal cross-vein re-entrant; the face neither keeled nor impressed; the larvae tapering anteriorly and posteriorly from the middle; the larvae posteriorly blunt and tail-less ... Eumerus
  • The lower outer marginal vein more or less parallel with the posterior wing margin; the upper outer marginal cross-vein not re-entrant; the face impressed; the larvae tapering posteriorly; the larvae tailed ... Brachypalpus

169(149).
  • The abdomen contrastingly patterned ... 170
  • The abdomen not contrastingly patterned... 171

170(169).
  • Wing veins R2+3 and R4+5 forming a closed cell; the upper outer marginal cross-vein re-entrant; antennae with their bases approximated; the larvae posteriorly blunt and tail-less; the anal segment of the larva shorter than the rest of the body ... Volucella
  • Wing veins R2+3 and R4+5 not forming a closed cell, but ending separately at the margin; the upper outer marginal cross-vein not re-entrant; antennae with their bases well separated; the larvae tailed; the anal segment of the larva at least as long as the rest of the body ... Sericomyia

171(169).
  • The antennal bristle apical, terminating the third segment; wings plain; the upper and lower outer marginal cross veins strongly stepped; the thorax pubescent with stiff bristles interspersed; the larvae posteriorly blunt and tail-less ... Hammerschmidtia
  • The antennal bristle dorsal (proximal to sub-apical); wings patterned; the upper and lower outer marginal cross veins slightly stepped; the thorax shaggy with soft hair; the larvae tailed ... Arctophila

172(83).
  • The antennal bristle simple (bare, or no more than shortly hairy) ... 173
  • The antennal bristle plumose... 177

173(172).
  • The abdomen conspicuously furry ... 174
  • The abdomen not conspicuously furry (short-haired to more or less hairless)... 176

174(173).
  • The upper and lower outer marginal cross veins more or less continuous; the upper outer marginal cross-vein gently curved or straightish; the larvae with hooks on the thorax ... Criorhina
  • The upper and lower outer marginal cross veins strongly stepped; the upper outer marginal cross-vein conspicuously bent near the base the base; the larvae without thoracic hooks... 175

175(174).
  • The head wider than the thorax ... Caliprobola
  • The head about the same width as the thorax ... Caliprobola
  • The head less wide than the thorax ... Pocota

176(173).
  • The abdomen contrastingly patterned; the thorax pubescent without stiff bristles interspersed (not shaggy); the larvae without thoracic hooks; the anal segment (segment 8) of the larva abruptly constricted basally into the long, narrow tail ... Caliprobola
  • The abdomen not contrastingly patterned; the thorax shaggy with soft hair; the larvae with hooks on the thorax; the anal segment (segment 8) of the larva tapered gradually to the spiracular process ... Brachypalpus

177(172).
  • The abdomen contrastingly patterned ... 178
  • The abdomen not contrastingly patterned... 179

178(177).
  • Wing veins R2+3 and R4+5 forming a closed cell; the upper outer marginal cross-vein re-entrant; antennae with their bases approximated; the larvae posteriorly blunt and tail-less; the anal segment of the larva shorter than the rest of the body ... Volucella
  • Wing veins R2+3 and R4+5 not forming a closed cell, but ending separately at the margin; the upper outer marginal cross-vein not re-entrant; antennae with their bases well separated; the larvae tailed; the anal segment of the larva at least as long as the rest of the body ... Sericomyia

179(177).
  • The antennal bristle apical, terminating the third segment; wings plain; the upper and lower outer marginal cross veins strongly stepped; the thorax pubescent with stiff bristles interspersed; the larvae posteriorly blunt and tail-less ... Hammerschmidtia
  • The antennal bristle dorsal (proximal to sub-apical); wings patterned; the upper and lower outer marginal cross veins slightly stepped; the thorax shaggy with soft hair; the larvae tailed ... Arctophila


To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. Insects of Britain and Ireland: the genera of Syrphidae (hoverflies). Version: 28th July 2015. delta-intkey.com’.

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