In Defense of Fuzzy Caterpillars

Posted by on Sep 16, 2017 in insects, Unmowed Blog | 3 comments

I’ve been seeing these little guys all over social media lately. They’re sort of cute, actually, black and white like little zebras, easy to spot on a green leaf. When I was a kid, I would have picked them up and put them on a stick and watched them crawl along, just for fun.

Photo from awwnverts

They’re called hickory tussock moths—they munch on hickory leaves mostly, but don’t cause huge amounts of damage to trees.

But on Facebook, I keep seeing these little caterpillars attached to words like “lethal,” “dangerous” and “terrifying.” And the scariest word of all: venomous.

So what’s the deal? Was I risking death when I picked up a tussock moth caterpillar in my youth? Are these little guys a life-threatening menace? In a word, NO.

They don’t bite or sting. They will not kill you. They’re not venomous in the sense that a cobra or a scorpion is.

The problem is that some of their bristles are what are called urticating hairs. Like the spines of a nettle, they can cause a rash on sensitive people, but it’s usually a pretty mild irritation. The skin on the palm of your hand is fairly thick, so you’re unlikely to have any problem from picking up a caterpillar. But if the caterpillar brushes against an area with sensitive skin, like your stomach or your neck, a reaction is more likely. Worst case scenario is one somehow gets stuck up a sleeve or in your underwear and your skin rubs against it. Unlikely, but possible.

It’s the way the caterpillar survives. When a blue jay grabs a caterpillar for lunch, the caterpillar thrashes back and forth, thrusting the urticating hairs into the bird’s face. The blue jay quickly learns to avoid white, fuzzy food. Later, when the caterpillar pupates, it uses the urticating hairs to make its own cocoon. The soft larva inside the cocoon is defenseless, but the cocoon would be an itchy mouthful for hungry predators.

So they’re fairly innocuous, certainly not lethal. You don’t want to rub a hickory tussock moth caterpillar on your sensitive areas. Don’t cuddle them against your cheek, don’t get the bristles in your eye. Don’t lick them, don’t eat them (people have done these things). But I’ve picked up many a caterpillar in my youth. We’re not talking black mambas here. It’s perfectly OK if a kid watches a tussock moth caterpillar crawl along a twig.

And please, try to resist the temptation to squish them. They’re a native species, they have a place in the food chain, and they grow up into harmless but absolutely gorgeous moths. Look at the beauty we’d miss.

For more info on itchy stuff (bugs, poison ivy and much more) check out my book ITCH! Everything You Didn’t Want to Know About What Makes You Scratch.


photo by Mike Boone on


  1. <3

  2. Love this article and the pics are even better.

    • Thank you! Yes, the pictures are beautiful–not taken by me! The caterpillar is from a great site called awwnverts, which is dedicated to “cute things without backbones.” They have some wonderful photos of creatures most people hate. And the adult moth is from, which is my go-to reference for all things bug-related.

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