The caterpillar of the spicebush swallowtail butterfly (Papilio trollus) mimics the rough green snake (Opheodrys aestivus).
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The caterpillar of the spicebush swallowtail butterfly (pictured here) exhibits Batesian mimicry – where a harmless animal mimics a dangerous or foul tasting one equipped with a warning system such as conspicuous coloration. The mimic gains protection because predators mistake it for the dangerous organism (called the model), and leave it alone. This form of mimicry is named after its discoverer, the 19th-century English naturalist Henry Walter Bates who was the first to describe a snake-mimicking caterpillar in the Amazonian rain forest in Brazil in the 1850’s. This caterpillar mimicked a highly venomous pit viper in coloration and behavior, and even elicited panic when shown to local villagers. Henry Bates documented many examples of mimicry in moths, butterflies and other insects, and his findings were embraced by Charles Darwin as evidence for natural selection at work.
For more on the science adventure story of Henry Walter Bates and his extraordinary 11-year journey through the Amazon as a young man in the 1850s, watch Amazon Adventure
The spicebush swallowtail third instar caterpillar was collected on HHMI’s Janelia Research campus on a sassafras bush, and the photograph was taken using a digital SLR camera and a macro lens.
Igor Siwanowicz, PhD, HHMI Janelia Farm Research Campus.