Invertebrates
Puss Caterpillar
Megalopyge opercularis · also called asp, southern flannel moth caterpillar
A puss caterpillar rests on a shade tree branch looking soft enough to gently pet, its dense, fur-like covering hiding a sting that ranks among the most painful an insect can deliver in North America. Nothing about its appearance warns you until it’s already too late.
Overview
The puss caterpillar, Megalopyge opercularis, is a venomous larval insect native to forest and grassland habitat across the southern and southeastern United States. Its deceptively soft, fur-like appearance conceals hidden venomous spines capable of delivering an intensely painful sting.
A disguise that invites the exact wrong reaction
Where most venomous animals advertise danger through bright warning colours, the puss caterpillar does the opposite, looking gentle and touchable right up until contact reveals the hidden spines beneath its deceptively soft fur.
Status
Least Concern — widespread and stable across suitable habitat throughout the southern and southeastern United States.
Puss Caterpillar: common questions
Why does the puss caterpillar look so harmless?
A puss caterpillar is covered in dense, soft-looking hair-like setae that give it an appearance resembling a small tuft of fur or a tiny cat, a deceptively harmless look that gives the species its common name, even though venomous spines are hidden beneath that same soft-looking fur.
How painful is a puss caterpillar sting really?
A puss caterpillar sting typically causes intense, immediate pain along with swelling, and the pain can radiate outward from the contact point and persist for hours, sometimes accompanied by nausea or other systemic symptoms in more severe cases, making it one of the most painful stings caused by any insect in North America.
What does a puss caterpillar turn into?
A puss caterpillar eventually pupates and emerges as an adult southern flannel moth, a fuzzy, comparatively harmless moth that looks quite different from its venomous larval stage, meaning the danger associated with the species exists only during its caterpillar phase.
Where might you encounter a puss caterpillar?
A puss caterpillar is commonly found feeding on the leaves of shade trees and ornamental shrubs across the southern and southeastern United States, sometimes bringing it into contact with humans working or playing near affected vegetation, which is why unexpected stings can occur when people brush against tree branches or fallen leaves.