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Project Noah Nature School
Papilio troilus
The Spicebush Swallowtail Caterpillar is one of the best mimics known. The caterpillar, in its early stages, resembles a bird dropping (brown caterpillar in image to left) and is found exposed during the day on the upper side of the leaves. After molting to the 4th instar (I believe there are 5 total instars in this species) the caterpillar turns green (large caterpillar). Both the early instars and the later ones display the snake's head mimicry, with large spots on the swollen thorax giving the appearance of a snake's head. The spots look like eyes, even to the point of having a white "highlight" to simulate moisture (below). The later instars roll up leaves, holding them together with silk. They stay in these retreats by day; a bird investigating the rolled up leaf will be confronted by a "snake" peering back at it.
Larvae start out with this coloration, which resembles bird droppings. Then, in later instars, they take on a greenish coloration.
Spotted on May 7, 2012
Submitted on May 7, 2012
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