Polyphemus of Greek mythology was a terrible cyclopean creature that enjoyed feasting on men. In the world of insects, Polyphemus is the name given to one of our largest moths that has not one eye, but four on its wings. These are not true eyes like the compound eyes on the head of Polyphemus. The false eyes or eyespots of Polyphemus result from hundreds of colored scales arranged in a pattern that resembles the eye of another animal like a bird or snake. Several species of insects evolved clever patterns of coloration resembling eyes on parts of their body where eyes really do not belong. 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 was 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.
After hatching from these eggs, and several small Polyphemus caterpillars devoured this hickory leaf.
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. A few weeks ago, two large and beautiful Polyphemus moths blundered into a parking lot, attracted, no doubt, by large lights illuminating the parking lot at night. Fortunately, they were male and female and with a little romance and luck, several dozen eggs were laid by the gal. The eggs hatched and a gaggle of hungry Polyphemus caterpillars consumes ever-increasing quantities of hickory leaves each day. Polyphemus caterpillars eat leaves from many kinds of trees including elm, oak, and walnut. 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 several four-eyed moths to return to the wild to scare the daylights out of would-be predators.
References
We thank Ellery for rescuing the Polyphemus moths and Sam, Brian, Scott, and Ada for keeping the caterpillars well fed. To learn more about Polyphemus, please visit the following web sites:
http://entnemdept.ufl.edu/creatures/MISC/MOTHS/polyphemus_moth.htm
http://enpp.auburn.edu/outreach/web-publications/polyphemus-moth/