Swallowtails on Your herbs

Before you remove that striped caterpillar…

A couple of years ago, two different clients reported back the same story: they'd found these striking, striped caterpillars on their parsley and removed them, thinking they were pests. Only later did they learn they'd evicted future swallowtail butterflies. That's when I realized I needed to get ahead of this to give people the heads-up before they found the caterpillars, not after.

The Good News: They're Not the Enemy

If you're growing parsley, dill, fennel, or carrots, there's a good chance you'll eventually host swallowtail caterpillars. And yes, they'll eat your plants. But they're not pests. They're guests in transition, and their impact is usually minimal compared to the magic they're about to create.

These little caterpillars, with their bold bands and tentacles (called "osmeterium"), are easy to recognize once you know what they are. They get adorably chubby in their final days in this form.

The Relocation Dilemma

If you absolutely must move a caterpillar, there's one critical rule: keep it on the same plant species it started on.

Swallowtail caterpillars do have multiple host plants, as I mentioned above. But here's where it gets tricky: a caterpillar that's bonded with your parsley may refuse to eat dill, even if you place it right in front of them. They're picky eaters, and forcing a diet change can stress or starve them.

So if you must relocate, move the caterpillar to another parsley plant in a safer location. Keep it on what they know. That simple choice could mean the difference between a successful chrysalis and a tragedy. (We get dramatic about butterflies around here.)

The Better Option: Let Them Stay

Honestly? The easiest path is to leave them where they are. Your herbs will recover. The caterpillar will pupate nearby, hidden and safe. And in a few weeks a gorgeous swallowtail butterfly will emerge and grace your garden with its presence.

The Bottom Line

Next time you find one of these caterpillars on your herbs, pause before removing it. A few nibbled leaves now means a swallowtail butterfly in your garden soon. It's a worthwhile trade.