from Pilgrim at Tinker Creek - chapter 4

"With a wingspread of up to six inches, the Polyphemus is one of the few huge American silk moths, much larger than, say, a giant or tiger swallowtail butterfly. The moth's enormous wings are velveted in a rich, warm brown, and edged in bands of blue and pink delicate as a watercolor wash. A startling 'eyespot,' immense, and deep blue melding to an almost translucent yellow, luxuriates in the center of each hind wing. The effect is one of a masculine splendor foreign to the butterflies, a fragility unfurled to strength." (61)

this is a Polyphemus moth

Note the two "staring eyes" on the underwings. These are known as "distraction patterns" and they are a common method of self-defense for moths. According to Peterson Field Guide to Eastern Forests:

"Often when a butterfly or moth is at rest, it will be cryptic, blending very well with its background, but many butterflies and moths "hedge their bets" against escaping predation by also employing distraction patterns in the event of discovery." (354-55)