The black fuzzy caterpillar you found in Louisiana is most likely one of three species: the giant leopard moth caterpillar, the salt marsh caterpillar, or the buck moth caterpillar. Two of these are completely harmless. One, the buck moth caterpillar, delivers a genuinely painful sting. Telling them apart is straightforward once you know what to look for.
Giant Leopard Moth Caterpillar
This is the most commonly encountered black fuzzy caterpillar in Louisiana and the one people photograph most often. It’s about 3 inches long, covered in shiny black, stiff bristles that fan outward like a bottle brush. The key identifier: when you startle it, it curls into a tight ball and reveals bright red or orange bands between its body segments. Those red rings are hidden when the caterpillar is stretched out and moving, so you may need to wait for it to feel threatened.
Despite looking intimidating, the giant leopard moth caterpillar is not a stinging species. Its bristles are solid, not hollow, so they carry no venom. You can safely relocate one with a leaf or piece of cardboard, though the stiff hairs can feel prickly against bare skin. These caterpillars are generalist feeders, munching on a wide variety of plants, and they eventually become striking white moths covered in black spots and rings.
Salt Marsh Caterpillar
Salt marsh caterpillars are smaller, topping out around 2.25 inches, and they’re covered in long, conspicuous tufts of hair sprouting from raised bumps on each segment. Their color is highly variable. Some are entirely black or dark brown, while others are a patchwork of black, orange, gray, and yellowish tones. If your caterpillar looks woolly and has noticeably mixed coloring, this is a strong candidate.
These caterpillars are common on broadleaf weeds like pigweed, but they also show up on garden vegetables including beans, tomatoes, lettuce, and carrots. They’re not considered stinging caterpillars, though some people report mild skin irritation from handling densely hairy species like this one. They’re primarily a garden pest rather than a health concern.
Buck Moth Caterpillar: The One to Avoid
The buck moth caterpillar is the black fuzzy caterpillar that gives Louisiana residents real trouble, especially in New Orleans where live oaks line the streets. At about 2 inches long, it’s dark brown to purplish black with numerous small yellow spots. The critical difference from the harmless species: instead of soft or bristly hairs, it has branched spines with red or black tips. These spines look sharper and more structured than the woolly fuzz on the other two caterpillars.
Those spines are hollow and connected to venom sacs. When they pierce your skin, they release a toxin that causes immediate burning pain, followed by swelling, redness, and sometimes blistering. Some people experience more severe reactions including widespread rash and intestinal discomfort. Buck moth caterpillars feed on oak leaves and often drop onto sidewalks, benches, and parked cars beneath the trees, which is how most people get stung unexpectedly.
When Each Species Is Active
Buck moth caterpillars have a predictable schedule in Louisiana. The adult moths emerge from the ground in late fall, typically November through mid-December. They mate and lay eggs on oak branches. Those eggs hatch between mid-February and April, and the young caterpillars feed and grow rapidly through spring. By early summer, the fully developed caterpillars crawl down the tree trunks in groups, burrow into the soil, and pupate underground for about six months. So the sting risk is highest from late February through May.
Giant leopard moth caterpillars are most visible in fall, when they’re fully grown and wandering across sidewalks and driveways looking for sheltered spots to overwinter. You’ll also see them in spring as they resume feeding before pupating. Salt marsh caterpillars tend to appear in late summer and fall, often showing up in gardens when their populations peak.
How to Tell Them Apart Quickly
- Shiny black bristles, curls into a ball showing red bands: Giant leopard moth caterpillar. Harmless.
- Long woolly tufts, variable color mix of black, brown, and orange: Salt marsh caterpillar. Harmless.
- Purplish black with yellow spots, branched spines with colored tips: Buck moth caterpillar. Venomous, do not touch.
The texture is the fastest clue. Soft or bristly hair means safe. Stiff, branching spines that look like tiny antlers or thorns mean stay away.
What to Do if You Get Stung
If a buck moth caterpillar stings you, resist the urge to brush it off with your bare hand, which will just drive more spines into your skin. Use a stick, credit card, or any tool to flick it away. Then press a piece of adhesive tape (duct tape, packing tape, even medical tape) firmly over the sting site and peel it off. This pulls embedded spines out of your skin and significantly reduces the irritation.
After removing the spines, wash the area thoroughly. Ice packs help with swelling and pain. Over-the-counter antihistamines and hydrocortisone cream can manage itching and rash. Most stings resolve within a few hours to a couple of days. If you develop hives spreading beyond the sting site, difficulty breathing, or significant swelling, that suggests an allergic reaction that needs medical attention.
Remove and wash any clothing that touched the caterpillar. The broken-off spines can cling to fabric and sting you again later.