Looking every bit like the Golden Alexander (Zizia aurea) flower buds on which they were laid, the pale yellow eggs of a Black Swallowtail (Papilio polyxenes) are next to impossible to find unless one is fortunate enough to see them in the act of being laid. Members of the parsley family (Golden Alexander, Wild Parsnip, Queen Anne’s Lace, Dill, Carrot) are host plants for most ravenous Black Swallowtail larvae, and thus that is where you will find their eggs. As they eat, the caterpillars absorb toxins from their host plant, which does not harm them but makes them distasteful to avian predators.
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.