Caterpillars of Pacific Northwest Forests and Woodlands
Photo Key to Species
Group B-1b -- Subgroups: Body wall smooth, except monarch butterfly - Species in group B-1a have a smooth body wall that is not extended into bumps, warts, tubercles, or horns. As an exception note the caterpillar of the monarch butterfly has four long filamentous tubercles.
Irregular middorsal markings - Species in this subgroup have middorsal saddles, dashes, or spots.