Via Live Science:
Johnson noticed that the insect's two right wings were typical of the females of its species — they were larger, and brown with yellow and white spots. But its two left wings were smaller and darker, with splashes of green, blue and purple, a pattern characteristic of males...Previously on TYWKIWDBI:
A butterfly expert later confirmed that the remarkable insect was a Common Archduke butterfly (Lexias pardalis) with a rare condition called gynandromorphy, which means outwardly having both male and female characteristics. (This is distinct from hermaphroditism, in which an organism has both male and female reproductive organs, but has external characteristics of one gender.)
The condition is most commonly noticed in birds and butterflies, whose two sexes can have very different coloration... Because gynandromorphy can be easily overlooked in species in which the two sexes look similar to each other, scientists don't know how rare the condition is.