Scanning electron microscope (SEM) view of the head of a milkweed butterfly caterpillar (Euploea sp.). The head has several small simple eyes on either side, and mandibles at its base. As the name suggests, the caterpillars feed on milkweed plants (Asclepias sp.), which are toxic to many animals. The caterpillars retain the toxin as protection from predators, and are brightly coloured with long projections on their body, to warn potential predators.