MWC Eco-brief: Butterfly mimicry

To be, or not to be, that is the question. The viceroy butterfly is commonly mistaken for a monarch. Known as Mullerian mimics, the toxic monarch and viceroy butterflies share a common warning color and pattern. This mimicry mutually benefits both species by deterring predators. Viceroy butterflies have crescent shaped black lines on their hind wings and a single row of white dots along the black wing edges. Monarchs lack the black crescent lines on the hind wings and have two rows of white dots along the black wing margins. Viceroy butterflies are also comparatively smaller than monarchs. The caterpillars of these two species are markedly different. The highly cryptic viceroy caterpillar is dependant upon host plants such as willow (Salix spp.), cottonwood and poplars (Populus spp.). In the Midwest, Monarch caterpillars rely on milkweed (Asclepias spp.) and bluevine (Cynanchum laeve), the latter of which is commonly mistaken as a weed in gardens. The photos in this post are of viceroys.