They’re back in Florida! The puss caterpillar might look warm and fuzzy, but don’t touch one. This venomous critter, also called the “asp caterpillar” (an asp is an Egyptian cobra), can cause pain that’s far worse than a bee sting. / Photos courtesy UF/IFAS

The Southern flannel mothMegalopyge opercularis, is an attractive small moth that is best-known because of its larva — the puss caterpillar — one of the most venomous caterpillars in the United States. So writes Donald Hall of the University of Florida’s Institute of Food and Agricultural Sciences.

At maturity, a puss caterpillar becomes a Southern flannel moth. The female (left) is larger than the male (right). Their wingspans range from about 1 to 1.5 inches.

In addition to the name “puss caterpillar,” this insect has been called the “Italian asp,” “possum bug,” “perrito” (Spanish for “puppy” or “little dog”) and “woolly slug,” he adds.


To watch a Weather Channel video on the puss caterpillar, visit

The bodies of puss caterpillars are usually completely hidden from sight by their thick coating of hair. However, the head and prothorax may be exposed when the larvae are moving about or occasionally when feeding, Hall notes.

The danger is well hidden

The larvae go through various stages of molting and become progressively more “hairy” with each molt. During each molting, the puss caterpillar has “rows of verrucae (in effect, warts that sprout stiff hairs) that bear hollow spines, each of which has a venom gland at its base,” Hall warns.

Beware: Those spines are obscured by the long, soft hairs. And these caterpillars love to hang out in citrus trees.