"Females are dimorphic. The yellow morph differs from the male in having a blue postmedian area on the dorsal hindwing. In the dark morph, the areas that are normally yellow are replaced with dark gray or black. The bluish postmedian area on the ventral hindwing has one row of orange spots.[11] A shadow of the "tiger stripes" can be seen on the underside of some dark females." (en.wikipedia.org) This swallowtail showed up at our Carolina phlox. I have never seen a brown swallowtail like this. It seems the female eastern tiger swallowtails can come in the typical yellow and black but also in these dark morph colors.