| 1 | Larger species, 21.0-28.0mm. Hindwing with cilia relatively short; cilia near end of vein 2 about one-quarter of greatest width hindwing |
| | Late June to early September. Forewing with apex rectangular, termen straight, little oblique; rather unicolorous ochreous to dark brown with some dark spots and dark longitudinal discal streak; occasionally veins marked with pale streaks. Frons and vertex ochreous. |
| - | Smaller species, 6.0-15.0mm. Hindwing with cilia relatively long, cilia near end of vein 2 of equal length greatest width hindwing |
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| 2 (1) | Forewing dark brassy or coppery, unmarked or nearly so |
| | Unmarked form, see couplet 3. |
| - | Forewing with distinct white or silvery spots or strigulae |
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| 3 (2) | Forewing without conspicuous white or silvery strigula at middle of dorsum, blackish apical hook absent |
| | 10.0-15.0mm. Late May to early August. Forewing shining bronzy with sometimes indistinct metallic golden costal and dorsal transverse streaks; a blackish tornal mark, enclosing two or three metallic dots and a black apical spot. Frons and vertex brassy, darker than forewing. See couplet 2. |
| - | Forewing with conspicuous white or silvery strigula at middle of dorsum; blackish apical hook present |
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| 4 (3) | Forewing with blackish apical spot enclosing a clear silvery dot |
| | 8.0-11.0mm. May and June. Forewing dark bronzy brown with white costal and dorsal streaks; some metallic dots near tornus. Frons and vertex dark greyish brown. |
| - | Forewing with apical spot without silvery scales |
| | Forewing with blackish apical spot sometimes bordered by silvery strigulae. Frons and vertex brassy. |
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| 5 (4) | Hindwing with dorsal cilia greyish, whitish tipped, becoming entirely white towards base |
| | 6.0-9.0mm. Early June to early August. Forewing rather evenly coloured bronzy brown; without distinct pre-apical silvery spot (another silvery spot near tornus present). |
| - | Hindwing with dorsal cilia unicolorous greyish |
| | Forewing somewhat paler in basal half. |
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| 6 (5) | Forewing with distinct pre-apical silvery spot before blackish apical spot |
| | 7.0-9.5mm. Early June to early September. Forewing with basal third greyish shading to dark bronzy brown in apical third; a second silvery spot in terminal area near tornus. |
| - | Forewing without distinct pre-apical silvery spot before blackish apical spot |
| | 6.0-9.0mm. Early May to early July. Forewing with basal half greyish shading to dark bronzy brown in apical half; in terminal area only one silvery spot near tornus. |
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