This black swallowtail flew into my yard and seemed to hone right in on my dill plant. It flew away to other backyards several times, always returning to the dill plant. Black swallowtail caterpillars love to eat feathery plants like carrots and dill, so the swallowtails lay their eggs on these plants. You can see it bending it's abdomen to deposit the eggs.
A dill plant growing in a suburban backyard.