One of the most painful stings of any insect in North America. Hidden under the soft-looking fur are venomous spines; contact causes immediate intense throbbing pain that can radiate up the limb. Do not touch it, and do not let a child touch it.
We identify, we don't diagnose. If you've been bitten or stung and symptoms develop, or you're worried, seek medical attention.
Size25–35 mm long
MarkingsLooks like a tuft of fur or a scrap of cotton wool — not obviously a caterpillar · Fur ranges from pale grey through gold to reddish-brown
WhereSouthern and southeastern US, on shade trees and shrubs.
SeasonTwo generations a year, most encounters late summer and autumn
How to tell it apart
Looks like a tuft of fur or a scrap of cotton wool — not obviously a caterpillar
Fur ranges from pale grey through gold to reddish-brown
Teardrop shape with a small tail-like point at one end
Venomous spines are hidden beneath the hair and are not visible
Found on oak, elm and citrus leaves, and on garden walls
Where you’ll find it
The southern and southeastern United States, from Texas across to Florida and up the seaboard to Maryland. It is most abundant in Texas and Florida.
Southern and southeastern US, on shade trees and shrubs.
Two generations a year, most encounters late summer and autumn.
How it behaves
It moves slowly on trees and shrubs and does not chase or fall on people. Almost every sting happens by accident: brushing a branch, sitting on a porch rail, or a child picking it up because it looks like something soft. The venomous spines are hidden entirely under the hair, so nothing about its appearance warns you.
What a bite looks like
A grid or train-track pattern of red marks matching where the spines touched, with swelling that can spread well beyond the contact point.
Immediate intense throbbing pain, often radiating up the limb, and frequently described as one of the worst stings of any North American insect. Nausea, headache and swollen glands can follow.
We identify, we don't diagnose or prescribe treatment. In the US, call Poison Control at 1-800-222-1222 for case-specific guidance, especially for severe pain, spreading swelling or a sting to a child. Call emergency services for difficulty breathing or swelling of the face or throat.
A skin mark cannot confirm which animal caused it. Read the bug bite and sting guide for the limits and the symptoms that should end an online search.
You’ve found one indoors
Do not touch it, and make sure children know not to. If one is on a doorframe or a play area, knock it off with a stick rather than a gloved hand — the spines can pass through thin fabric.
Common questions
How painful is a puss caterpillar sting?
Severe. It is widely regarded as the most painful caterpillar sting in North America, with immediate throbbing pain that can radiate up the arm or leg and last for hours.
What do I do if I touch one?
Avoid rubbing the area and contact Poison Control or a clinician for case-specific advice. Use emergency services for difficulty breathing or swelling of the face or throat.
Why does something so soft-looking sting?
The hair is a disguise. Underneath it are hollow venomous spines connected to venom glands, and the soft appearance is precisely what gets people to touch it.
José Belem Hernández Díaz · CC-BY