They Look Like Pretty Patterns—But What Hatches Will Make Your Skin Crawl (2 of 3)

She came over last spring, holding a leaf like it was a piece of evidence from a crime scene. “What do you think this is?” she asked, showing me the same neat clusters I’d seen before. She said she’d been wiping them off with her bare fingers for days, thinking they were just “plant freckles.”

I felt my stomach drop. She had no idea.

I explained: those perfect little pinwheels are the eggs of the Mourning Cloak butterfly. Beautiful creatures, yes. But before they turn into delicate wings fluttering through the sky, their caterpillars have to eat. And they don’t nibble politely—they devour. Leaves, branches, sometimes entire saplings stripped bare in a matter of weeks.

Her jaw dropped. “So you’re telling me I’ve been touching these with my hands?”

I nodded. What I didn’t say right away—because I didn’t want to terrify her—is that when those eggs hatch, the caterpillars don’t just cling to the plant. They swarm. Dozens of them crawling over each other, spiny and wriggling, covering every inch of whatever they land on. It’s a sight that makes your skin crawl. And once they spread, they don’t stop.

I walked her back to her garden, and sure enough, there were patches of them everywhere—on her rose bushes, her lilac, even her grapevine. Whole armies waiting to be born.

“You need to be careful,” I told her. “Don’t touch them. Don’t even try to scrape them off with your hands. You don’t want to risk those spines breaking your skin, and you definitely don’t want to spread them accidentally.”

The look on her face said it all.

That night, she texted me a photo of her grapevine. The eggs had hatched. Hundreds of caterpillars moving like a dark wave across the leaves. She’d gone inside, shut the blinds, and couldn’t bring herself to step into the yard again.

And here’s the truth: most people have no idea what these clusters are until it’s too late. They look almost decorative, like tiny stars pressed into a leaf. But once you’ve seen what they become, you’ll never forget it.

So if you notice them on your plants—stop. Don’t touch. Don’t brush. Don’t pretend they’re harmless. Because once those eggs crack open, you’ll be dealing with something you’ll wish you’d never ignored…