Eyespots on the wings of Polyphemus might startle a would-be predator. M. J. Raupp
How can you not love Greek mythology? Polyphemus, a terrible, one-eyed giant that enjoyed feasting on men, notably Odysseus and his crew. Fitting that to escape from the cave of Polyphemus, the crew blinded him with a spear and snuck out of the cave with a herd of sheep. Giants also populate the world of insects. Polyphemus is the name given to one of our largest moths that has not one eye, but four on its dorsal wings. These are not true eyes like the compound eyes on the head of the Polyphemus moth. These false eyes or eyespots are an evolutionary masterpiece created by hundreds of colored scales arranged in patterns resembling the eye of another animal like a bird, mammal, or snake.
This montage begins with a very pregnant female Polyphemus moth that decided to lay her eggs on a lawn chair. Hopefully, the caterpillars made their way to an oak or maple tree like this one. Here is what this giant silk moth caterpillar looks like as it ascends the tree. Watch as smaller and larger caterpillars munch on one of their favorite foods, the leaves of oaks. One kind human found this female Polyphemus marooned inside a parking garage after a storm. With a little assistance, this magnificent moth took flight. Here’s looking at you Polyphemus. Video and image credit: Nancy Koran, Peihan Orestes, and Jenny Milward.
Several species of insects employ clever patterns of coloration resembling eyes on parts of their body where eyes really do not occur. For example, in a previous episode of Bug of the Week, we met the larva of the swallowtail butterfly adorned with two sinister eyespots on its thorax. These false eyes helped create the illusion of a serpent for a larva that is really a tasty caterpillar. Scientists believe that these eyespots aid in defense of insects and other animals in several ways. Eyespots may resemble the eyes of a potential predator’s own predators. Moths and butterflies are tasty fare for many birds, but in turn, birds are meals for larger winged predators such as owls. Eyespots and color patterns on the wings of some moths resemble the face of an owl. Imagine the terror of a bird about to eat what appears to be a harmless moth, when suddenly the hungry bird confronts the face of an owl. A second way that eyespots may aid in defense is to direct an attack away from vulnerable parts of the body. Some predators attack the head of the victim where maximum damage results. False eyespots on less critical parts of the body such as wings may steer a first strike away from a lethal spot and provide time for the intended prey to escape.
The beautiful Polyphemus caterpillar is one of the largest caterpillars in North America M.J. Raupp
Last week, I received images of a very pregnant female Polyphemus moth that had settled on a patio and proceeded to lay batches of eggs on a lawn chair. I know not what became of the eggs or the moth, but with luck the eggs hatched and the tiny caterpillars, which don’t eat lawn chairs, found their way to sustaining leaves of elm, oak, walnut, or more than a dozen other woody trees and shrubs. These marvelous caterpillars will gain more than a thousand times their birth weight before they spin cocoons of leaves and silk and change into pupae. With luck, in a few weeks, we will have dozens of four-eyed moths returning to the wild to scare the daylight out of would-be predators.
Acknowledgement Special thanks to Nancy Koran for providing inspiration and images for this episode. Cool camera work by Peihan Orestes and Jenny Milward helped create this story. The fantastic Caterpillars of Eastern North America by David Wagner was used as a reference.