Great Yellow Mormon Caterpillar Papilio lowi

The caterpillar of many swallowtail butterflies has two distinct phases. The early instars are shiny brown and white to mimic bird droppings for protection from predators. Above is the caterpillar of the Great Yellow Mormon, but other Mormons and the Citrus Swallowtails are similar.

The later phase of the caterpillar is green to blend with the citrus leaves it eats. When startled (not illustrated) most swallowtails produce a forked red horn from the head to mimic a snake's tongue.

The last instar of the green phase is particularly artistic, with more white, some pale blue and very realistic "eye" spots which are not eyes at all and not even on the head.

The chrysalis reverts to looking like poop (appropriately called a pupa).