This is a rare example of a gynandromorph moth, recently hatched at the Natural History Museum in London. While the left wings of this Antheraea frithi are female, the right wings are clearly male.
“Gynandromorphs are incredibly rare,” says museum moth researcher Ian Kitching (press release). “We only have 200 such specimens in our collection of some 9 million butterflies and moths.”
Sadly for this poor moth, there really is a dividing line down its body. The female half has a partial set of female organs and the male half a partial set of male organs. Neither function.
“The bilateral gynandromorphy that this moth shows is the result of an error involving the sex chromosomes at the first cell division,” says Kitching. “Sometimes, such errors occur later in development, whence the gynandromorphy is mosaic and the separation into the two sexes isn’t so clearly defined.”
Image: Natural History Museum