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.
Straight longitudinal lines - Species in this subgroup have longitudinal lines that are straight with at least one even edge.