Georgia is home to at least half a dozen caterpillar species that can deliver a painful, venomous sting. These aren’t the kind that cause harm if swallowed. Instead, they’re covered in hollow, quill-like spines connected to venom sacs that pierce your skin on contact. Most encounters happen between late summer and early fall, when caterpillars are large and actively feeding on common trees like oaks, elms, and willows.
Puss Caterpillar: The Most Dangerous
The puss caterpillar is one of the most venomous caterpillars in the United States, and it’s found throughout Georgia. It’s the larval stage of the southern flannel moth and looks deceptively soft, like a small tuft of fur or cotton. That “fur” hides rows of hollow spines, each with a venom gland at its base. Every larval stage can sting, but toxicity increases as the caterpillar grows larger.
A puss caterpillar sting produces immediate, intense burning pain. A red grid-like pattern appears on the skin, matching the layout of the spines that made contact. Swelling follows, and nearby lymph nodes may become tender and enlarged. Beyond these local effects, some people experience systemic symptoms: headache, fever, nausea, vomiting, rapid heart rate, and low blood pressure. In rare cases, seizures, muscle spasms, and abdominal pain have been reported. The venom has blood cell-damaging properties, which partly explains why reactions can be so severe compared to other caterpillar stings.
Saddleback Caterpillar
The saddleback caterpillar is one of the easiest stinging caterpillars to identify. It’s about three-quarters of an inch long, bright green, with a distinctive brown saddle-shaped spot on its back. It moves in a slug-like fashion because its legs are unusually short and lack the tiny hooks most caterpillars use for grip. Four prominent knobs at the front and rear, plus smaller knobs along the sides, are covered in stinging spines. Even newly hatched saddlebacks already have these spine-covered knobs.
A sting causes immediate pain that radiates to nearby lymph nodes. Swelling and redness can persist for over a week, making this one of the longer-lasting caterpillar stings you might encounter in Georgia.
Io Moth Caterpillar
Io moth caterpillars are bright green to yellow, about two inches long when mature, with a narrow red line bordered by a white line running along each side. They’re covered in branched, yellow-green spines tipped in black. These caterpillars are generalist feeders, showing up on oaks, elms, willows, roses, apple trees, clover, and even corn. That wide diet means you can encounter them in forests, gardens, and yards alike.
The sting feels similar to other spine-bearing caterpillars: sharp pain, redness, and swelling at the contact site. Some people develop blistering or a more widespread rash.
Buck Moth Caterpillar
Buck moth caterpillars are dark brown to purplish-black, around two inches long, with numerous yellow spots and branched black spines that may have red or black tips. They feed primarily on oak and willow trees from spring through midsummer. You’re most likely to encounter them when mature larvae leave the trees and wander across the ground looking for a place to pupate. There’s only one generation per year, so encounters tend to cluster in a short window.
Other Stinging Species in Georgia
Several additional species round out the list. Tussock moth caterpillars are common across the state, with multiple species present including the white-marked tussock moth and fir tussock moth. The hag moth caterpillar (sometimes called the monkey slug) has an unusual flat, hairy shape with stinging spines hidden among brown, curved projections. The spiny oak slug caterpillar, true to its name, is found on oaks and delivers a mild but noticeable sting.
All of these species share the same basic defense mechanism: hollow spines that break off in your skin and release venom. The severity varies by species, with the puss caterpillar at the top and spiny oak slugs at the milder end.
When Stinging Caterpillars Are Most Active
Most stinging caterpillars in Georgia reach their peak size between late summer and early fall. Caterpillar populations grow rapidly through summer as moths complete multiple generations. By August and September, the larvae are at their largest and most venomous, and they’re also more likely to be wandering away from host trees. This is the period when accidental contact is most common, whether you’re gardening, raking leaves, or leaning against a tree trunk.
You don’t have to touch a live caterpillar to get stung. Shed skins (called exuviae) from puss caterpillars retain their venomous spines. Fallen caterpillars on outdoor furniture, playground equipment, or railings are another common source of stings.
What to Do After a Sting
The first priority is removing the spines still embedded in your skin. Press a strip of adhesive tape or packing tape firmly over the sting site, sticky side down, then peel it off. Repeat several times with fresh tape. This pulls out the tiny hollow spines that are too small to remove with tweezers.
After removing the spines, wash the area thoroughly with soap and water to help clear residual venom. Apply an ice pack or a baking soda paste promptly to reduce pain and limit swelling. Over-the-counter hydrocortisone cream can help with the local skin reaction. Standard antihistamines may provide some relief for itching, though they’re reportedly less effective for caterpillar stings than they are for bee or wasp stings.
Most stings resolve on their own within a few hours to a few days, though saddleback stings can cause redness and swelling lasting over a week. Seek medical attention if you develop symptoms beyond the sting site: difficulty breathing, throat or tongue swelling, widespread hives, dizziness, rapid heart rate, or a sudden drop in blood pressure. These are signs of a severe allergic reaction. Very young children, older adults, and people with compromised health are more likely to experience serious reactions.
Risks to Dogs and Cats
Pets are at risk too, especially dogs that investigate caterpillars with their noses or mouths. An animal’s fur provides some protection against skin stings, so dermal reactions are less common than you might expect. The bigger danger is oral contact. A dog that mouths or eats a stinging caterpillar may drool excessively, shake its head, paw at its face, and have difficulty swallowing. Irritation to the tongue, lips, and throat can develop, along with stomach and intestinal inflammation.
If your pet has contacted a stinging caterpillar, rinse its mouth with water if you can do so safely. Tape can be used to remove visible spines from the skin or gums. Cold compresses help with swelling. Eye exposure is rare but serious, requiring thorough flushing and potentially a veterinary ophthalmology exam if irritation continues. Allergic reactions in pets are possible and may need professional treatment.