I was out in the garden picking some kale, peppers, and beans this morning. On my way out I walked by the carrots and decided to pull one and see how it was looking. When I knelt down I saw a couple visitors on the greens: big, chunky caterpillars. I took a few pictures and went inside to look up what they were. I have a butterfly book that I love. It shows them at all stages of their lifecycles so you can identity what you're seeing whether it is an egg, caterpillar, chrysalis or butterfly.
I think this is pretty close to what I saw:
The book says it is an Eastern Black Swallowtail. It says their favorite host plants are dill, fennel, and Queen Anne's lace (also called wild carrot). So it makes sense that they like carrots because the greenery looks the same on all these plants: lacy, thin leaves. It doesn't look like they are hurting the plants too much so I'm going to leave them be. Maybe we will get some pretty black butterflies in the garden too.