This is a "wild dill" or "prairie parsley" plant, growing just outside my office, which had several Swallowtail butterfly caterpillars on it -- too many, I think -- they're going to run out of food. Also this plant is in an inconvenient spot, and after this, I removed it.

But first, I migrated these critters to other plants in an area I don't intend to mow.

Swallowtails have a particular connection to this plant. They lay their eggs on it and then the caterpillars live off of it prior to forming a chrysalis to transform into butterflies, continuing the cycle.

One year we raised a Swallowtail from the caterpillar in a jar, and then released it once it hatched out of the pod. I like to imagine these little critters might even be descendants of that one butterfly!