Wikipedia: Butterflies are insects in the macrolepidopteran clade Rhopalocera from the order Lepidoptera, which also includes moths. Adult butterflies have large, often brightly coloured wings, and conspicuous, fluttering flight. The group comprises the large superfamily Papilionoidea, which contains at least one former group, the skippers (formerly the superfamily “Hesperioidea”) and the most recent analyses suggest it also contains the moth-butterflies (formerly the superfamily “Hedyloidea”). Butterfly fossils date to the Paleocene, which was about 56 million years ago.
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Die Gross-Schmetterlinge der Erde : eine systematische Bearbeitung der bis jetzt bekannten Gross-Schmetterlinge : Bd.6 (1935). Stuttgart :Alfred Kernen,1909- The large butterflies of the earth: a systematic treatment of the previously known large butterflies: Vol. 6 (1935)