Complex sentence: The caterpillars of "Papilio" species are usually smooth and vary in color from green to yellow-orange with black markings to mimic the appearance of bird droppings or the head of another bug with large "eyes".
Split into simpler sentences: The caterpillars of "Papilio" species are usually smooth and vary in color from green to yellow-orange. In addition, they have black markings to mimic the appearance of bird droppings or the head of another bug with large "eyes".