I've never grown dill in my garden before, but I grew some this year and made cucumber pickles with it. When I planted it I remembered that when my grandpa grew dill, colorful green/black/yellow caterpillars would feed on it and I wondered if they'd come. Yep - today I noticed dozens of those caterpillars on my dill plants - they're really eating them up.
I got on the Internet, found pictures, and discovered that these dill-eating caterpillars turn into Eastern Black Swallowtail butterflies (Papilio polyxenes). It seems that here in the Ozarks we also have our own similar, rare Black Swallowtail species, Papilio joanae - so these caterpillars are one or the other. They're welcome to the dill, I'm done with it, and since I'm not growing any other plants from the carrot family that they feed on - we don't have a problem.
I'm glad to have these - according to the article I read the butterflies from these caterpillars will emerge next May or June. Instead of a new pest in the garden as I'd feared, we'll have more butterflies around, so I'll start planting some dill every year (and always get my pickles made before these hungry guys hatch out). Here's a picture I took several years ago of a Black Swallowtail on one of my tomato plants.
Congratulations Ozark! Maybe you will be lucky enough to see some of them emerge from their chrysalises. They emerge very tiny with scrunched up wings and have to hang around for a while (sometimes an hour or so, depending) before the wings are fully extended and rigid enough for them to fly. Pretty soon you'll be hooked and start looking online for other host plants to add to your garden that other butterflies in your area will lay eggs on...i'll betchya :-D