The red spots refered to in the name appear on the undersides of the wings. Red-spotted Purples are members of the Family Nymphalinae, a group with includes the Buckeye, Viceroy, and Comma and Question Mark butterflies. Pyle also notes that the Red-spotted Purple is a mimic of the Pipevine Swallowtail, a species distasteful and toxic to birds.
Birds therefore tend to avoid both species.
Scott reports that adult Red-spotted Purples feed on a varied diet of sap, fruit, nectar, carrion, dung, and decaying wood. This individual was photographed in central Indiana.