1 | Maxillary palpus long, with five segments. Forewing almost uniformly yellowish, ochreous or greyish |
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- | Maxillary palpus rudimentary or obsolete. Forewing darker, golden, coppery or bronzy |
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2 (1) | Antenna distinctly annulated pale grey and dark brown, at least in basal half |
| 15.0-20.0mm. Mid April to early June. Forewing yellowish grey, reticulated brownish. Frons pale ochreous yellow, vertex pale ochreous brown. |
- | Antenna unicolorous whitish or yellowish, occasionally with faint annulation in basal half or spotted brownish below |
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3 (2) | Hindwing upperside with very narrow scales, in male confined to basal half, in female to less than half, broad scales on rest of wing |
| 13.0-17.0mm. May to early July. Forewing comparatively short and rounded, shining pale ochreous, indistinctly, rather uniformly brownish strigulated; an ill-defined dark spot at end of cell. Hindwing pale grey with cilia pure yellow basally and yellowish grey in distal half. Frons white, vertex ochreous yellow. |
- | Hindwing upperside with very narrow scales on greater part of wing |
| Occasionally whole hindwing with narrow scales. |
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4 (3) | Forewing greyish brown, reticulated darker; discal spot conspicuous |
| 13.0-17.0mm. May and June. Hindwing with cilia dark grey, concolorous with wing. Frons pale greyish brown, vertex yellowish white with white hair-scales between antennae. |
- | Forewing yellowish or greyish brown, not or faintly strigulated darker; discal spot absent or indistinct |
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5 (4) | Larger species, 17.0-22,0mm. Hindwing pale grey, cilia yellowish |
| April to June. Forewing ochreous yellow, faintly strigulated darker, discal spot absent. Hindwing upperside wholly narrow-scaled in male, but with broader scales in apical area. Frons yellowish white, vertex ochreous yellow. |
- | Smaller species, 13.0-17.0mm. Hindwing greyish, cilia concolorous with wing |
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6 (5) | Forewing with tornal spot. Antenna male two times length costa forewing, antenna female one and a half length of costa forewing |
| 13.0-17.0mm. May and June. Forewing yellowish, brown at base costa. Frons yellowish white, vertex ochreous yellow. |
- | Forewing without tornal spot. Antenna male three times length costa forewing, antenna female two times length of costa forewing |
| 13.0-17.0mm. May and June. Forewing in male greyish brown, in female greyish ochreous, both sexes brown in basal area and in costal half. Frons white to pale ochreous yellow; vertex ochreous yellow to ochre, rarely shading to brownish posteriorly. |
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7 (1) | Forewing bronzy, purple and brassy with broad, dark purplish black median fascia |
| 13.0-16.0mm. July (in England). Frons and vertex in male black, in female ferruginous. Forewing with short, black subcostal dash. |
- | Forewing without dark purplish black median fascia |
| Occasionally an ill-defined slightly darker transverse shadow occurs in middle of forewing. |
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8 (7) | Forewing with yellow fascia or pale yellowish transverse dorsal spot beyond middle |
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- | Forewing without pale markings |
| Forewing occasionally with small pale spots. |
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9 (8) | Smaller species, 8.0-9.5mm. Forewing with pale yellowish transverse dorsal spot just beyond middle, not quite reaching dorsum, sometimes extended towards costa and almost reaching it |
| Early May to late June. Frons and vertex black. Antenna black, apical fourth white; in male slightly longer than costa forewing, in female shorter than costa. Forewing coppery bronzy, purplish tinged; sometimes a second pale yellowish spot near base. |
- | Larger species, 11.0-23.0mm. Forewing with complete yellow fascia from dorsum to costa |
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10 (9) | Forewing in addition to yellow fascia with one or two violet-edged yellowish spots in terminal area of wing |
| 14.0-15.0mm. Mid May to mid June. Frons and vertex brownish. Antenna in male not thickened in basal half, two and a half to three times length costa forewing; antenna in female thickened in basal half, one and a quarter length costa forewing. Forewing with ground colour brown. |
- | Forewing with yellow fascia only |
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11 (10) | Larger species, 15.0-23.0mm. Forewing at least in basal area with golden yellow streaks between veins |
| Mid May to mid July. Frons and vertex ferruginous yellowish. Antenna in male slightly thickened basally, three and a half times length costa forewing; in female antenna not thickened, length one and a third times length costa. Forewing with ground colour shining dark brown. |
- | Smaller species, 11.0-13.0mm. Forewing without golden yellow streaks between veins |
| Late May to mid July. Frons and vertex ferruginous. Antenna in male two and a half times length costa forewing, in female antenna in basal half thickened and densely scaled blackish brown, length slightly more than length costa. Forewing with ground colour shining dark violet brown. |
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12 (8) | Forewing with black longitudinal basal streak beneath costa |
| 10.0-13.0mm. Late June to late July. Frons and vertex in male slightly thickened basally, black, in female ferruginous. Antenna in male thickened basally but gradually narrowing from scapus to one third, length one and two thirds length of costa forewing; in female not thickened, one and a fifth length of costa. Forewing golden bronzy, becoming coppery postmedially. |
- | Forewing without black basal streak |
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13 (12) | Smaller species, 9.5-12.5mm |
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- | Larger species, 13.0-20.0mm |
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14 (13) | Frons near antenna ferruginous yellow |
| 10.0-12.0mm. Late May to mid August. Vertex ferruginous yellow. Antenna in male not thickened in basal third, but with prostrate pectination on segments 8-12, length two and a half length costa forewing; in female thickened in basal third, without pectinations, length one and a third length costa. Forewing purplish. |
- | Frons near antenna black |
| 9.5-12.5 mm. Late April to early July. Vertex ferruginous yellow. Antenna in male not thickened basally, twice length costa forewing; in female slightly thickened basally, one and a half length costa. Forewing shining brassy bronzy. |
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15 (13) | Vertex black, occasionally mixed ochreous |
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- | Vertex ferruginous |
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16 (15) | Antenna from one-fifth to two-thirds black, rest white. Forewing brightly shining dark brassy bronze with a greenish tinge |
| 12.5-17.0 mm. Mid April to early July. Antenna in male not thickened, but with prostrate pectinations on segments 9 and 10, length three times length costa forewing; in female slightly thickened basally, without pectinations, length one and a half length costa. Forewing with costa tinged coppery. |
- | Antenna basally ringed or barred whitish and black, rest pure white. Forewing bronzy golden, tinged coppery |
| 13.5-15.5mm. March to May. Antenna slightly thickened basally, prostrate pectinations on segments 11 and 12, length two and a half times length costa forewing. Forewing costally and distally purplish. |
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17 (15) | Larger species, 15.0-20.0mm. Forewing long with costa and dorsum nearly parallel up to apical area; apex pointed; comparatively dull bronzy golden, costa reddish purple |
| Late June to mid August. Antenna in male three times length costa forewing, in female two and a half times length costa. |
- | Smaller species, 13.0-16.0mm. Forewing broadened distally; apex rounded; brightly shining bronzy golden, costally and apically purplish |
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18 (17) | Flagellum not thickened towards base; scapus without long tuft. Frons rough-haired |
| 13.5-15.5mm. March to May. Antenna without pectinations, length one and a quarter length of costa forewing. Forewing costally and distally purplish. |
- | Flagellum gradually thickened towards base or scapus with long tuft. Lower part of frons metallic |
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19 (18) | Forewing with basal half shining golden bronze. Hindwing with dorsal area shining purplish golden |
| 13.0-16.6mm. June to August. Forewing with distal area dark coppery, tinged purplish; an ill-defined brownish violet transverse shadow in middle of wing. Antenna in male three times length of costa forewing, in female one and a fifth length of costa. In The Netherlands most probably partenogenetic. |
- | Forewing with basal half blackish violet, only slightly golden tinged. Hindwing with dorsal area dark violet with faint golden tinge |
| 13.0-16.0mm. Mid June to early August. Forewing almost wholly with same ground colour; the ill-defined transverse shadow in middle of wing broad and tinged blackish blue. |
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