This is a male Eastern Tiger Swallowtail. Adult males are yellow, with four black "tiger stripes" on each fore wing. The trailing edges of the fore and hind wings are black which is broken with yellow spots. On the medial margin of the hind wing next to the abdomen there are small red and blue spots. I captured this photo on 8/7/2004 at 3:57 PM along the Conewago Creek at Satori Farm in Lewisberry, PA. I believe this is also the first time I photographed a butterfly.