A: Thank you for sharing the photo. This is the larvae or caterpillar of the Black Swallowtail butterfly. The black swallowtail larvae are often confused with the monarch butterfly caterpillar as the colors are quite similar. However, if you look closer you will notice distinctive differences in the yellow and black markings of the two caterpillars. On the black swallowtail caterpillar, the yellow coloring breaks up the black whereas on the monarch the yellow and black seem to form more straight bands. Once you see them side by side you will never make the mistake of confusing them. It is interesting how different both of the caterpillars look from the adult butterfly. You would think the adult butterfly would at least keep the same color as the caterpillar – yellow, black and green. However, the monarch butterfly develops into an orange and black butterfly while the black swallowtail is almost completely black. Nature never ceases to amaze me.