The past couple of weeks have brought as many as ten swallowtails at a time to our butterfly bushes. The white one has been especially popular. I'm not sure if that is because of its color or its height. It is our tallest bush and the swallowtails concentrate on its top half.
Mostly we get the classic Eastern Swallowtail, although we have seen an occasional dark form female and a few Spicebush Swallowtails as well.
Sometimes a pair seem dance together in the air, spiraling upwards, trading places, almost touching.