In this area the range of the eastern swallowtail crosses that of the Canadian swallowtail this can sometimes make identification difficult. The Canadian swallowtail is smaller and has a continuous yellow band on the trailing edge of the forewing as compared to the eastern where the band is interrupted by black. Occasionally giant swallowtail come north making identification even trickier.
This is a male eastern tiger swallowtail. The female of the species has orange and blue spots mixed into the black border of the wings, particularly near the tail. Females can also come in a dark form that appears similar to a black swallowtail. This dark form is not very common, especially this far north, and I have yet to see a dark form female.