Luna moths carry a pair of elongated hindwing tails ending in a spiralled tip. Tethered-moth experiments in which free-flying big brown bats attacked luna moths in a flight room found that intact moths escaped roughly half of encounters, while moths with their tails experimentally removed were captured in the large majority of attacks.
The mechanism is acoustic misdirection rather than concealment. The twisted tail tips act as strong reflectors of the bat's echolocation calls, and because they trail and flutter behind the moth they generate a moving echo that is often more salient than the return from the body. Bats aim at the echo and close on the tail, tearing it away while the moth flies on. Damaged tails are common in wild-caught specimens.
Comparative work indicates that hindwing tails have evolved independently several times within the saturniids, and that longer tails give better protection. Saturniids lack the ears that many moths use to hear bats, so this is a defence that works without detection. Whether the tails also serve in mate choice has been raised but not demonstrated.