Female eastern tiger swallowtail (Papilio glaucus) yellow morph, Big South Fork National River & Recreation Area, 2015.

Males are yellow with four black 'tiger stripes' on each forewing. The outer edge of the wing is black with a row of yellow spots. Wing veins are marked by black. Females are dimorphic, with yellow and dark morphs. The yellow morph differs from the male by a noticeable blue postmedian area on the dorsal hind wing (similar to the blue postmedian area of the dark morph.) The dark morph is dark gray or black instead of yellow. Pictured: yellow morph female.