The red-spotted purple is a common butterfly of the UM Field Station twice a year in May-June and August-September. It differs from the other “dark” swallowtails in that it has orange spots along the margin of the front wings but has no tails. The red-spotted purple belongs to the family of brush-footed butterflies and is common throughout much of the eastern United States. Males are generally a little larger than females, otherwise the two are identical. Red-spotted purples are active in the day, from morning until just after dusk. Their caterpillars feed on willow, birch, cottonwood and American hornbeam.