Antheraea polyphemus can have the wingspan of a small bird, ranging from 10-15 cm (4-6 inches). This specimen is only about 12 cm wide, still significantly wider than my palm. A common large moth of North America, this one was observed resting adjacent to the door of my office complex in Forbes, Minnesota.
I think it's a male based on the wide lashes on its antennae, which are used to collect pheromones that home in on the location of a mate. By the time it's an adult, the male polyphemus has only one thing on its mind. With only vestigial mouth parts, it can't even eat. The polyphemus moth is named after a mythical cyclops from Homer's Odyssey due to the eye-like patterns on it's hind (lower) wings, which are believed to confuse predators.