The dorsal wings of male Sasakia charonda butterflies display a striking blue iridescent coloration, which is accentuated by white, orange-yellow and red spots, as well as by brown margins. The ventral wings also have a variegated, but more subdued, pattern. We investigated the optical basis of the various colors of intact wings as well as isolated wing scales by applying light and electron microscopy, imaging scatterometry and (micro)spectrophotometry. The prominent blue iridescence is due to scales with tightly packed, multilayered ridges that contain melanin pigment. The scales in the brown wing margins also contain melanin. Pigments extracted from the orange-yellow and red spots indicate the presence of 3-OH-kynurenine and ommochrome pigment. The scales in the white spots also have multilayered ridges but lack pigment. The lower lamina of the scales plays a so-far undervalued but often crucial role. Its thin-film properties color the majority of the ventral wing scales, which are unpigmented and have large windows. The lower lamina acting as a thin-film reflector generally contributes to the reflectance of the various scale types.

中文翻译：

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紫色大帝王蝶（Sasakia charonda）的着色原理

雄性Sasakia charonda蝴蝶的背翅显示出惊人的蓝色彩虹色，白色，橙黄色和红色斑点以及棕色边缘突显出这种颜色。腹侧翼也有杂色，但更柔和。我们通过应用光学和电子显微镜，成像散射法和（显微）分光光度法研究了完整机翼以及孤立的机翼鳞片的各种颜色的光学基础。突出的蓝色虹彩是由于鳞片带有紧密堆积的，包含黑色素色素的多层山脊所致。棕色翼缘的鳞片也含有黑色素。从橙黄色和红色斑点中提取的颜料表明存在3-OH-犬尿氨酸和全色素。白色斑点中的鳞片也具有多层脊，但缺乏色素。鳞片的下部叶片到目前为止被低估，但通常起关键作用。它的薄膜特性使大多数腹侧鳞片着色，这些鳞片没有色素且具有大的窗口。用作薄膜反射器的下层通常有助于各种刻度类型的反射率。