10/09/2026
All right, fans of the Fat Cat(erpillar)s – we've got our winner!
It was a close call, but the Spicebush Caterpillar won the vote for best Fat Cat!
These charismatic caterpillars begin life when a female spicebush butterfly lays eggs on one of their host plants. They typically feed on spicebush, sweet bay, tulip tree, and sassafras. Throughout their lives, they are masters of deception.
Life as a young caterpillar is dangerous – they are highly sought after by birds and other animals as abundant sources of protein. What better way to deter hungry predators than by making oneself look like crusty excrement? Young spicebush caterpillars mimic bird droppings to stay safe while they feed.
They have more than one disguise in their life cycle toolkit. As they approach their final instars, or molts, they shed their gross costumes and don a little green snake outfit! When they feel threatened, they enlarge the body segment with eye spots to make their serpent façade convincing.
That’s not all! When they're not feeding, they burrito themselves in the host plant's leaves, using silk to bring the edges together. When you find a spicebush, or one of the host plants, check it for “leaf-rittos.”
As the caterpillars near pupation, they turn orange. Just like other butterflies, they form a chrysalis. Once again using mimicry as a defense mechanism, the chrysalis closely resembles another leaf along the stem. They may spend up to 20 days in the chrysalis before emerging as an adult; however, they sometimes overwinter in their pupal form.
Adults are mostly black with flashes of blue and orange at the base of the wing. They mimic the pipevine swallowtail, a toxic species.
Big thanks to everyone who voted and shared. Congratulations to the masterfully deceptive Spicebush Caterpillar, our Fat Cat Week winner!
To view the many life stages of this incredible caterpillar, follow these links:
https://www.insectimages.org/search?q=spicebush%20butterfly
https://content.ces.ncsu.edu/spicebush-swallowtail