Owl butterfly

A yellow-fronted owl butterfly, Caligo telamonius, resting on a trunk in Alajuela, Costa Rica. With its wings closed, the underside shows one large ringed eyespot, black at the center with a pale rim, set in feathery patterning. Whether that spot really copies an owl's eye has long been debated. A 2015 experiment gave a strong answer: great tits shown images on a screen shied away from realistic owl-butterfly eyespots about as much as from real owl eyes, and more than from equally bold spots that looked less like eyes. Seen at rest at dusk, it is easy to believe.