Before I started gardening, I would often see many Red-spotted Purples sipping sap from the leaves of my neighbor's trees.  They were quite common back then.  In recent years, I have usually seen it only once a year.  Although mainly a fruit eater and sap sipper, it likes to take nectar from my Butterfly Bush.  In 2003, I saw two of them together for more than a week.  Hopefully they are in the process of making a comeback.