Illustrated field comparisonMonarch or viceroy?The hindwing crossline usually resolves a clear open-wing photograph; wear, angle, and other orange-and-black species can complicate a brief view. The textbook framing has also changed. Viceroys were long described as harmless mimics of toxic monarchs, but both are now recognized as at least somewhat distasteful, so current sources treat them as Müllerian co-mimics. Viceroy defense comes from salicylic acid taken up from its willow hosts.
