| 1 | Forewing with vein 7 absent |
| | Forewing often ochreous or reddish brown; hindwing broad and unmarked. |
| - | Forewing with vein 7 present |
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| 2 (1) | Forewing with veins 8 and 9 separately out of 7, the latter rising from cell |
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| - | Forewing with stalk of veins 8 and 9 from cell, vein 7 free from cell or stalk of veins 8 and 9 rising from vein 7 |
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| 3 (2) | Wings brownish violet with two yellow transverse lines and yellow cilia. Body slender |
| | One species, Hypsopygia costalis. Other species of this subfamily key out in couplet 6 of this key. |
| - | Forewing marked otherwise, hindwing unmarked; cilia not yellow. Body stout |
| | Pronounced sexual dimorphism. |
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| 4 (2) | Forewing with common stalk of vein 8 and 9 rising from cell, vein 7 free from cell |
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| - | Forewing with common stalk of vein 8 and 9 rising from vein 7 |
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| 5 (4) | Hindwing with transverse vein well-developed |
| | Forewing often triangular. Hindwing often with markings. Includes subfamilies Schoenobiinae, Nymphulinae, Odontiinae, Evergestinae and Pyraustinae (narrow sense) |
| - | Hindwing with transverse vein absent or obsolete |
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| 6 (4) | Hindwing with transverse vein well-developed |
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| - | Hindwing with transverse vein absent or obsolete |
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| 7 (6) | Forewing in female wholly suffused blackish grey or dark greyish brown, in male pale grey with some discal spots. Maxillary palps pencil-like in male, in female obsolete |
| | One species, Lamoria anella. Pronounced sexual dimorphism. Length labial palp less than half eye-diameter (male) or twice eye-diameter (female). Body stout. Other species of this subfamily key out in couplet 3 of this key. |
| - | Forewing usually brownish, often with pale longitudinal median streak. Maxillary palp well-developed, with projecting hair-scales causing triangular shape |
| | Length labial palp at least two and a half times eye-diameter. Body slender. |
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