Bilateral gynandromorphy is a condition in which an organism develops the sexual characteristics of both sexes. This typically occurs as an early female zygote loses an X chromosome during mitotic division. The portion that remains XX develops female characteristics while the portion that is now XO develops male characteristics (Le & Rizk, 2012). This occurs in arthropods and occasionally in birds as well. This European Earwig (Forficula auricularia Linnaeus) was found in Stanislaus County, California. The “male” portion of the forceps is large and curved while the “female” portion is short and straight.

Read more about bilateral gynandromorphy in butterflies and chickens!