In a previous episode we worried about the fate of the beleaguered monarch butterfly, whose population east of the Mississippi is threatened by habitat destruction and degradation throughout its native range. However, all news is not bad news for butterflies. This week I was delighted to spot numerous caterpillars of three marvelous native butterflies, black, spicebush, and giant swallowtails.
While weeding around a newly transplanted sassafras tree, I noticed small nibbles and curious folds on several leaves. Closer inspection of these folds revealed small larvae of the spicebush swallowtail that could have passed for bird droppings. Hiding inside rolled or folded leaves is a common disappearing act used by caterpillars of many species to escape the eyes and beaks of hungry birds. If this ruse fails, then looking like a bird dropping is probably a clever way to avoid being consumed because, well, what self-respecting bird wants to eat bird poop?
Here in the folded leaf of sassafras, a spicebush swallowtail caterpillar escapes the eyes of hungry predators.
As the spicebush caterpillar grows and develops, it switches to plan B and takes on the appearance of a serpent with two large eyespots on its thorax. These large eyespots strongly resemble a reptilian eye and it is believed that this disguise helps the caterpillar deter predators such as birds. Why? Think about what eats a caterpillar, often a bird; and what eats a bird, often a snake. So if you are a caterpillar, one way to scare away birds is to resemble a snake and this is precisely what the spicebush swallowtail does.