I generally have such a hard time distinguishing between the yellow and black-colored swallowtails, especially in flight. Sometimes they flutter in wafts high up in the treetops and other times they're spastic through a natural corridor like a crazy cat chasing a laser light. I meant to ask Dr. Shapiro how he tells the difference, but I was already struggling with information overload much of the day. We also spotted western tiger (Papilio rutulus, aka Pterourus rutulus), two-tailed (Papilio milticaudatus, aka Pterourus milticaudata), and anise (Papilio zelicaon, more pictures) swallowtail butterflies. This distinctively light-colored pale swallowtail was kind enough to be mud-puddling so that I could get a half-way decent picture.