Insects of Britain and Ireland: the genera of hoverflies (Syrphidae)

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L. Watson and M. J. Dallwitz

Character list

#1. <Nomenclature:>/

~ (‘alternatively’) is here used to indicate ‘sometimes not unreasonably included in or reduced to’.

#2. <Common name(s)>/

The adults

#3. The flies <mimicry>/

1. bumblebee-like <Apocrita-Aculeata, Apoidea: Apidae>/

2. hivebee-like <Apocrita-Aculeata, Apoidea: Apidae>/

3. resembling a potter bee <Apocrita-Aculeata, Apoidea: Anthophoridae (potter-bees)>/

4. Nomada-like <Apocrita-Aculeata, Apoidea: Anthophoridae (homeless/cuckoo-bees)>/

5. resembling a mining bee <Apocrita-Aculeata, Apoidea: Andrenidae>/

6. resembling Colletes <Apocrita-Aculeata, Apoidea: Colletidae (gum bees)>/

7. megachilid bee-like <Apocrita-Aculeata, Apoidea: Megachilidae>/

8. halictid bee-like <Apocrita-Aculeata: Halictidae>/

9. vespid wasp-like <Apocrita-Aculeata, Vespoidea: Vespidae>/

10. hornet-like <Apocrita-Aculeata, Vespoidea: Vespidae>/

11. resembling Eumenes <Apocrita-Aculeata, Vespoidea: Eumenidae (potter and mason wasps>/

12. sphecid wasp-like <Apocrita-Aculeata, Sphecoidea: Sphecidae (digger wasps)>/

13. cimbicid sawfly-like <Symphyta, Tenthrenidoidea: Cimbicidae>/

14. cephid sawfly-like <Symphyta, Cephoidea: e.g., Cephus, Calamenta>/

15. pamphiliid sawfly-like <Symphyta, Megalodontoidea: e.g., Neurotoma>/

16. resembling a wood-wasp <Symphyta, Siricoidea: Siricidae>/

17. muscid-like <cf. bluebottles, house-flies, etc.>/

18. not suggestive of mimicry <implicit>/

#4. The flies <colour of body>/

#5. The flies <size>/

1. minute <2–5 mm long>/

2. small <5–10 mm long>/

3. medium sized <10–15 mm long>/

4. large <15–20 mm long>/

#6. The flies <length>/

mm long/

This character of obvious potential value having become unfashionable in more recent times, the data have been compiled from Walker (1851) and Verrall (1901) (in the case of the former by converting from ‘lines’ to millimetres).

#7. Wings <length>/

mm long/

#8. The head <relative maximum widths of head and thorax>/

1. wider than the thorax/

2. about the same width as the thorax/

3. less wide than the thorax/

#9. The face <colour>/

1. ground-coloured at least part yellow/

2. entirely dark in ground colour/

#10. The face <flat or retreating, or otherwise>/

1. flat or concave in the region between the antennae and the mouth/

2. 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>/

Conspicuous differences in shapes of Hoverfly faces as viewed in profile have loomed large in keys for 160 years, but the present attempt at compilation suffers from the fact that characters adequate for preparing comparative descriptions to professional standards have never been competently defined.

#11. The face <presence of a central prominence or knob between the antennae and the oral margin>/

1. with a central knob <median prominence or tubercle>/

2. without a central knob/

#12. The face <surface>/

1. longitudinally keeled/

2. neither keeled nor impressed <unreliably implicit>/

3. impressed/

#13. The face <whether protuberant below in lateral view>/

1. produced below and extending beyond the antennae/

2. not extending below beyond the antennae <excluding aristae>/

#14. The face <form>/

1. drawn out into a horizontal cone as long as the rest of the head/

2. not elongated horizontally into a cone as long as the rest of the head/

#15. The face <wether tuberculate>/

1. with tubercles/

2. without tubercles/

#16. The face <elongation/tuberculation>/

1. elongated and tuberculated/

2. short and smooth/

#17. The frons <whether inflated>/

1. markedly inflated/

2. not inflated/

#18. The frons <surface>/

1. pitted or channelled/

2. smooth/

#19. The eyes <bare or hairy>/

1. hairy/

2. bare/

#20. The eyes <whether rimmed along the facial border>/

1. rimmed along their facial borders for much of the height of the face/

2. not rimmed along their facial borders for much of the height of the face <if at all>/

#21. Antennae <length>/

1. relatively short, drooping <shorter than the head>/

2. relatively long, porrect <as long as the head>/

#22. Antennae <insertion>/

1. with their bases approximated <or contiguous>/

2. with their bases well separated/

#23. Antennae <colour>/

1. black/

2. red/

3. ferruginous <rust coloured>/

4. yellowish/

5. tawny/

#24. The third <bistle-bearing> antennal segment <shape>/

1. ovoid or orbicular/

2. linear/

3. almost semicircular, with the upper edge straight and the arista near the apex/

#25. The antennal bristle <whether apical>/

1. apical <terminating the third segment>/

2. dorsal <proximal to sub-apical>/

#26. The antennal bristle <length relative to segment bearing it>/

1. shorter than the third segment/

2. about as long as the third segment/

3. much longer than the third segment/

#27. The antennal bristle <whether plumose>/

1. simple <bare, or no more than shortly hairy>/

2. plumose/

#28. <Compound> eyes <whether meeting above the antennae>/

1. asymmetric, nearly or quite connected above the antennae <holoptic>/

2. rounded, well separated/

#29. The maxillary palps <number of segments>/

segmented/

#30. The maxillary palps <porrect or drooping>/

1. porrect/

2. drooping/

‘Porrect’: extending more or less horizontally, or ascending, rather than drooping.

#31. The humeri <whether bare or hairy>/

1. bare <often obscured by the appressed, deeply concave rear of the head>/

2. hairy, and readily visible behind the head <the head well forward, not concave behind>/

#32. The thorax <indumetum>/

1. shaggy with soft hair/

2. pubescent without stiff bristles interspersed <not shaggy>/

3. pubescent with stiff bristles interspersed/

#33. The thorax <whether patterned>/

1. patterned/

2. plain/

#34. The thorax <thoracic dorsum, whether exhibiting a “death’s head” figure>/

1. black with pale longitudinal and transverse markings which produce a skull-like figure/

2. not exhibiting a skull-like figure/

#35. The thorax <whether longitudinally striped>/

1. with longitudinal stripes/

2. without longitudinal stripes/

#36. The thoracic striping <whether lateral only>/

1. lateral only/

2. not lateral only <implicit>/

#37. The thoracic striping <presence of shining yellow side-lines>/

1. exhibiting sharply defined, yellow lateral lines/

2. without well defined lateral lines/

#38. The scutellum <form>/

1. somewhat convex, with undefined edge/

2. flat, with a well defined edge/

#39. The scutellum <colour>/

1. at least partly yellow/

2. aeneous <lustrous bronze>/

3. brownish, ferrugineous or tawny/

4. black/

5. whitish/

#40. Wings <plain or patterned>/

1. patterned/

2. plain/

#41. Wings <conspicuousness of the stigma>/

1. with a conspicuous dark stigma/

2. without a conspicuously dark stigma/

#42. Wings <presence of minute black flecks>/

1. exhibiting tiny uniformly spaced black flecks along the hind edges/

2. without black flecks along the hind edges/

#43. Wings <position in repose>/

1. divergent in repose/

2. incumbent and almost parallel in repose/

#44. Wings <presence of the vena spuria>/

1. with a vena spuria <implicit>/

2. apparently without a vena spuria/

#45. Wing veins R2+3 and R4+5 <whether forming a closed cell R1>/

1. forming a closed cell <the marginal cell, cell R1>/

2. not forming a closed cell <these veins ending separately at the margin>/

#46. The anterior cross vein R-M in <wing> cell R5 <location>/

1. crossing it <and the vena spuria> before <proximally to> the middle of the adjoining discal cell/

2. crossing it <and the vena spuria> at or beyond the middle of the adjoining discal cell/

#47. <Wing> vein R4+5 <presence of deep curve>/

1. with a conspicuous curve projecting into the cell R5/

2. without a conspicuous curve projecting into the cell R5/

#48. <Wing> vein R4+5 <presence of unconnected transverse veinlet>/

1. with a short, backwardly projecting, incomplete transverse veinlet located distally to the cross veinlet in cell R5/

2. without a backwardly projecting, incomplete transverse veinlet <implicit>/

#49. <Wing> vein R <proximal to the submarginal cell, presence of bristles>/

1. bearing bristles/

2. without bristles <as distinct from fine hairs>/

#50. The lower outer marginal <wing> vein <closing the discal cell, aspect>/

1. markedly diverging from the posterior wing margin/

2. slightly diverging from the posterior wing margin/

3. more or less parallel with the posterior wing margin/

#51. The <junction of> upper and lower outer marginal cross veins <stepping>/

1. more or less continuous/

2. slightly stepped/

3. strongly stepped/

#52. The upper outer marginal <wing> cross-vein <closing cell R5, shape>/

1. gently curved <or straightish>/

2. <more or less> conspicuously bent near the base the base/

3. conspicuously bent well above the base <towards the middle>/

#53. The upper outer marginal <wing> cross-vein <closing cell R5, detail>/

1. bent at a sharp angle/

2. curved on the bend/

#54. The upper outer marginal <wing> cross-vein <closing cell R5, alignment>/

1. strongly angled to vein R4+5, so that cell R5 is markedly extended towards the wing tip/

2. joining vein R4+5 almost at right angles, so that cell R5 is not extended towards the wing tip/

#55. The upper outer marginal <wing> cross-vein <re-entrant or not>/

1. re-entrant <bending inwards to r4+5 at an angle of less than 90 degrees as viewed from the wing tip>/

2. not re-entrant/

#56. The alula <(axillary lobe) of the wing, development>/

1. distinct/

2. indistinct/

#57. The <wing> thoracic squamae <presence of dorsal hairs>/

1. with long hairs on their dorsal surfaces/

2. without long hairs dorsally/

#58. The front tibiae and/or tarsi <simple or modified>/

1. dilated in males, broad and flattened in females/

2. simple <neither broadened nor flattened>/

#59. The hind legs <colour>/

1. partly yellow/

2. black or at most narrowly pale at the knee/

#60. The hind femur <ornamentation>/

1. with a large triangular plate at its distal end/

2. with a tooth towards its distal end/

3. distally with neither a triangular plate nor a tooth/

#61. The metasternum <shape>/

1. entire, broad over its whole length/

2. reduced, the sclerotized part small with the central area diamond-shaped/

#62. The anterior anepisternum <whether pilose>/

1. at least partly pilose/

2. bare/

#63. The hypopleuron <meron> <hairs>/

1. exhibiting long hairs on its upper transverse ridge/

2. with no long hairs on its upper transverse ridge/

#64. The abdomen <relative (maximum) widths of thorax and abdomen>/

1. wider than the thorax/

2. about the same width as the thorax/

3. narrower than the thorax/

#65. The abdomen about <approximate length>/

#66. The abdomen <shape in outline as viewed from above>/

1. oval/

2. more or less fusiform/

3. ovate <distally broadened>/

4. oblong/

5. obovate <distally narrowed>/

6. clavate <distally broadened>/

7. linear/

#67. The abdomen <whether petiolated>/

1. proximally petiolated/

2. not petiolated <implicit>/

#68. The lateral margins of the <abdominal> tergites <presence or absence of a beaded rim>/

1. exhibiting beaded rims/

2. smoothly rolled over and without beading/

#69. The abdomen with <segments>/

segments apparent/

#70. The male abdomen <number of visible segments>/

1. with 4 visible segments/

2. with 5 visible segments/

#71. The abdomen <number of conspicuous tergites>/

1. dominated by the large tergites 2 and 3, tergite 4 being minute or not visible/

2. with tergites 2, 3 and 4 all more or less well developed <equal in length>/

#72. The abdomen <hairiness>/

1. conspicuously furry/

2. not conspicuously furry <short-haired to more or less hairless>/

#73. The abdomen <whether colour-patterned>/

1. contrastingly patterned/

2. not contrastingly patterned/

#74. The <abdominal> patterning <source>/

1. attributable to the furry hair coat/

2. not attributable only to the hair coat/

#75. The tergite patterning involving <tergite numbers>/

1. 1/

2. 2/

3. 3/

4. 4/

5. 5/

#76. The colour-patterned tergites marked with <colour>/

1. whitish/

2. yellow/

3. tawny <to orange-ish>/

4. orange/

5. red/

6. silvery or greyish/

#77. The tergite patterning <whether comprising obliquely longitudinal marks>/

1. comprising pale, straight, obliquely longitudinal markings on either side/

2. not comprising obliquely longitudial marks <implicit>/

#78. The <conspicuous> tergite patterning <restriction>/

1. confined to tergite 2/

2. confined to tergite 3/

3. not confined to one tergite <implicit>/

#79. The <paler> interrupted band on tergite 2/

1. reduced to small paired spots/

2. not reduced to small spots/

#80. The dorsum of tergite 2 <golf-club shaped spots>/

1. with golf-club shaped spots/

2. without golf-club shaped spots/

#81. The dorsum of tergite 2 <whether exhibiting a wineglass-shaped black area>/

1. exhibiting a wineglass-shaped black area <this cupular above, and narrow-based along the junction with tergite 3>/

2. without a wineglass-shaped black area <implicit>/

#82. The dorsum of tergite 3 <shape of partially-interrupted pale band in dorsal view>/

1. with a sunglasses-shaped pale partially-interrupted pale band/

2. with a brassiere-shaped pale partially-interrupted band/

3. with neither a sunglasses-shaped nor a brassiere-shaped partially-interrupted pale band <implicit>/

#83. The dorsum of tergite 3 <presence of moustache-shaped pale marking>/

1. with a pair of pale marks in the form of a moustache/

2. not marked in the form of a moustache <implicit>/

#84. The <paler> tergite bands <whether medianly interrupted>/

1. medianly <darkly> interrupted/

2. partially interrupted/

3. entire/

#85. The <paler> tergite bands <width>/

1. narrow <much less wide than the segments>/

2. wide <almost as wide as the segments>/

#86. The <paler> tergite bands <shapes>/

#87. <Abdominal> tergites 2–4 <extent of shiny-ness>/

1. equally shiny-metallic all over, without dull patches/

2. dulled dorsally <one or both shining metallic only laterally>/

#88. The spiracles of the third <adult> abdominal segment <location>/

1. borne in the middle of each side/

2. borne at or near the anterior corner of each side/

#89. The pale abdominal markings <opaque or translucent>/

1. opaque/

2. somewhat translucent/

Larvae and pupae

#90. The larvae <segmentation>/

1. detectably segmented <on close examination, but often obscurely so: implicit>/

2. not detectably segmented <by external examination>/

The literature pursued to date (see References) contains much woolly discussion of an ‘ecological’ kind on Hoverfly life histories, but a competent account of larval morphology has yet to be seen. The present attempted compilation of comparative data will be unreliable.

#91. The larvae <shape in outline>/

1. broader posteriorly, tapered to the head/

2. tapering anteriorly and posteriorly from the middle/

3. tapering posteriorly/

#92. The larvae <shape of rear>/

1. long tailed, tapering posteriorly into a long breathing tube/

2. shortly tailed to the spiracular process/

3. tail-less, posteriorly with only a short <often somewhat dorsal> spiracular process/

#93. The larvae <whether posteriorly tailed>/

1. tailed <to the posterior spiracular process>/

2. posteriorly blunt and tail-less <excluding the posterior spiracular process>/

#94. The anal segment <segment 8 of the larva, whether abruptly tailed>/

1. tapered gradually to the spiracular process/

2. abruptly constricted basally into the long, narrow tail/

#95. The anal segment <relative length>/

1. at least as long as the rest of the body/

2. shorter than the rest of the body <implicit>/

#96. The larvae <flattening and prolegs>/

1. scarcely flattened <usually with 7 pairs of conspicuous prolegs>/

2. flattened <usually without conspicuous prolegs>/

#97. The larvae <background colour>/

1. green/

2. not green/

#98. The larvae <whether longitudinally striped>/

1. longitudinally striped/

2. not longitudinally striped/

#99. The larvae <whether colour-patterned>/

1. <colour> patterned/

2. plain <not colour-patterned>/

#100. The larvae <translucence>/

1. translucent/

2. not translucent <implicit>/

#101. The larvae <dorsal projections>/

1. with dorsal projections/

2. dorsally smooth, without projections <implicit>/

#102. The larvae <lateral form>/

1. with conspicuous lateral projections <including serrate>/

2. laterally smooth <without projections: implicit>/

#103. The larvae <presence of dorsal or lateral thoracic hooks>/

1. with hooks on the thorax/

2. without thoracic hooks/

#104. The mouth <of the larva, presence of triangular sclerites in front view>/

1. with a triangular sclerite on either side/

2. without triangular sclerites/

#105. The anal segments <of the larva, horn-like projection>/

1. with a pair of curved, horn-like projections <excluding ‘hooks’>/

2. without horn-like projections <implicit>/

#106. The anal segments <of larvae, presence of lappets>/

1. with lappets/

2. without lappets/

#107. The larvae <general environment>/

1. aquatic/

2. semi-aquatic <inhabiting wet material>/

3. non-aquatic <implicit>/

#108. The larvae <feeding habits. See Notes and data comments.>/

1. phytophagous <feeding on living plant material>/

2. saprophagous <feeding in decaying organic matter>/

3. coprophagous/

4. consuming stored produce/

5. mycophagous/

6. predatory/

#109. The larvae <phytophagous> feeding on <food plant families>/

1. Alliaceae/

2. Amaryllidaceae/

3. Compositae/

4. Crassulaeae/

5. Hyacinthaceae/

6. Iridaceae/

7. Liliaceae/

8. Pinaceae/

9. Primulaceae/

10. Ranunculaceae/

11. Rosaceae/

12. Scrophulariaceae/

13. Umbelliferae/

14. Zingiberaceae/

#110. The <mycophagous> larvae recorded in fruit-bodies of/

1. Amanita/

2. Boletus/

3. Leccinum/

4. Suillus/

5. polypores/

#111. The <saprophagous> larvae <habitats>/

1. in sap runs/

2. in rot-holes/

3. in decaying sap under loose bark/

4. in rotten wood/

5. in decaying tree roots/

6. in decaying vegetation/

General comments

#112. <General comments:>/

Classification

#113. Subfamily <Chandler 2002>/

1. Syrphinae/

2. Milesiinae/

3. Microdontinae/

#114. Tribe <of Syrphinae, Chandler 2002>/

1. Bacchini/

2. Paragini/

3. Syrphini/

#115. Tribe <of Milesiinae, Chandler 2002>/

1. Callicerini/

2. Cheilosiini/

3. Chrysogastrini/

4. Eristalini/

5. Merodontini/

6. Pelecocerini/

7. Pipizini/

8. Sericomyiini/

9. Volucellini/

10. Xylotini/

British representation

#116. <Number of species in Britain>/

species in Britain/

#117. <Distribution in Britain>/

#118. E.g., <scientific and common names of British representatives>/


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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