Mimicry in North American checkerspot butterflies: Euphydryas phaeton and Chlosyne harrisii (Nymphalidae)

An examination of the phenetics, ecology and distribution of Chlosyne harrisii suggested that it was a potential mimic of the unpalatable Euphydryas phaeton. The wing undersurfaces of the adults are very similar and the larvae are virtually identical. The geographic range of both butterflies is the northeastern United States and both are inhabitants of wet meadow habitats where they may fly together. The life histories of both species are closely synchronized. A series of feeding experiments using blue‐jays as predators showed first, that C.harrisii is palatable, and second, suggested that the birds could not distinguish between C.harrisii and E.phaeton on the basis of visual cues. Thus, Charrisii seems to be an effective Batesian mimic of E.phaeton.