Puss Caterpillars in North Carolina Can Cause Hours of Pain, Swelling

Southern flannel moths, known as puss caterpillars, trigger swelling, nausea, and excruciating discomfort in anyone who makes contact with them. These bugs rank among the most venomous creatures in North Carolina, even though they appear soft and harmless.

"They are one of the more venomous insects in the state and are painfully venomous," Matt Bertone, director and entomologist at the Plant Disease and Insect Clinic at N.C. State University, told The News & Observer in a Wednesday, March 25 email. "But barring an allergic reaction, stings are not going to cause any serious issues."

One visitor got stung at Falls Lake in the Triangle. He called it the worst pain he'd ever felt. The N&O covered his story back in 2018. These critters have long, thick, gray-to-tan hairs with a blunt front that makes them resemble mice or toupees.

Puss caterpillars earned this nickname because they look like pussycat fur, according to the N.C. State Extension. Rusty-red crests run down their backs. Short, toxic spines cover their bodies.

In North Carolina, you'll find them most often around the Piedmont or coastal areas. Trees and forests provide their homes. They feed on elms, maples, hackberries, hollies, oaks, and sycamores.

Winter arrives, and the caterpillars hide in cocoons. Spring comes, and they finish growing. You might spot them starting in May, but October brings peak activity when the second generation hatches.

"They can't jump or shoot venom at people, nor are they fast, so there is no danger in just observing them," Bertone wrote. "However, most encounters happen when people accidentally brush up against them or touch them, causing the caterpillars to sting using modified hairs."

Stings create an initial burning feeling, then numbness sets in. Pain persists for hours, though it weakens after sixty minutes. Swelling sticks around for days.

Victims might get headaches, fever, itching, stomach discomfort, chest pain, trouble breathing, numbness, and vision problems, the extension wrote. Anyone experiencing severe reactions needs emergency care right away.

First, wash the affected spot and dry it with a hair dryer set on low. Tape pulls out the insect's hairs. Dab on rubbing alcohol, calamine lotion or a baking soda paste, then ice the area.

Eric LoPresti, an assistant professor of ecology at the University of South Carolina, said people who prune plants or work outside should wear pants or long-sleeved shirts. Stings don't happen often, but the risk exists.