Larva of black swallowtail butterflies most likely.

Yup. I grow dill just for them. This year they must have laid dozens of eggs
on my dill and there wasn't enough. Some I moved over to my Queen Ann's lace,
but I was surprised that a few moved on over to the cilantro I had near by and
seemed happy munching it. I never knew they liked cilantro. Next year I will
have to remember to sow the dill every couple of weeks so there will be plenty
of them for the caterpillars.

joelle