Ever since the first black swallowtail caterpillars turned up in my dill patch, I’ve been referring to the little guys as “him,” provoking some friends and relatives to accuse me of being sexist. Well, now I know that (for the most part) I was right. My fourth black swallowtail emerged today–a beauty like all the others (photo, left). But she was the first female of the lot. How can I tell?
The answer is in the markings on the wings. The top sides of the males’ wings are predominantly black and yellow, with only a tiny patch of blue–and of course, those wonderful orange eye spots at the bottom to distract predators (photo, right). By contrast, the female’s wings have a much larger band of blue across the bottom, and the yellow spots on the upper wings are less pronounced.
As for the underside of the wings, they provide no guidance. They have the same bold markings as the males’ wings, as seen in this photo of my hour-old female–perhaps my favorite picture of the summer. (Check out the chrysalis, still attached to the stick beneath her.) It gives me great pleasure to say, “Welcome, Madame Butterfly.”