This butterfly is half male and half female. The condition is called bilateral gynandromorphism and can be found in birds, insects and crustaceans.
“It’s thought that bilateral gynandromorphism occurs when two sperm enter an egg. One of those sperm fuses with the nucleus of the egg and a female insect develops. The other sperm develops without another set of chromosomes within the same egg. Both a male and a female insect develop within the same body.”
Source: I Fucking Love Science.