The chief reason is the back wings of the male monarch, which, seen against the light, change from their original gold to red, to green, to purple and blue, like a kaleidoscope or a prism in the sun.
珠光黃裳鳳蝶所以能豔冠群蝶，主要是它雄蝶的後翅像面三稜鏡，逆光看，會由原來的金黃色轉換成紅、綠、藍、紫等色澤，像萬花筒般瑰麗多變。