Adaptations to divert the attacks of visually guided predators have evolved repeatedly in animals. Using high-speed infrared videography, we show that luna moths (Actias luna) generate an acoustic diversion with spinning hindwing tails to deflect echolocating bat attacks away from their body and toward these nonessential appendages. We pit luna moths against big brown bats (Eptesicus fuscus) and demonstrate a survival advantage of ∼47% for moths with tails versus those that had their tails removed. The benefit of hindwing tails is equivalent to the advantage conferred to moths by bat-detecting ears. Moth tails lured bat attacks to these wing regions during 55% of interactions between bats and intact luna moths. We analyzed flight kinematics of moths with and without hindwing tails and suggest that tails have a minimal role in flight performance. Using a robust phylogeny, we find that long spatulate tails have independently evolved four times in saturniid moths, further supporting the selective advantage of this anti-bat strategy. Diversionary tactics are perhaps more common than appreciated in predator-prey interactions. Our finding suggests that focusing on the sensory ecologies of key predators will reveal such countermeasures in prey.antipredator defense | bat-moth interactions | Lepidoptera | Saturniidae P redators are under pressure to perform incapacitating initial strikes to thwart prey escape. It is thought that prey, in turn, have evolved conspicuous colors or markings to deflect predator attack to less vulnerable body regions (1, 2). Eyespots are a wellknown class of proposed deflection marks (3), which are found in a variety of taxa, including Lepidoptera (3) and fishes (4), but only recently have experiments convincingly demonstrated that these color patterns redirect predatory assault. Eyespots on artificial butterfly (5) and fish (4) prey draw strikes of avian and fish predators. Eyespots on the wing margins of woodland brown butterflies (Lopinga achine) lure the attacks of blue tits (Cyanistes caeruleus) (6). Brightly colored lizard tails also divert avian predator attacks to this expendable body region (7).Deflection coloration is unlikely to be an effective strategy against echolocating bats, as these predators have scotopic vision and poor visual acuity unsuited for prey localization and discrimination (8). Most bats rely on echoes from their sonar cries to image prey and other objects in their environment-they live in an auditory world (9). Thus, we would expect a deflection strategy, effective against bats, to present diversionary acoustic signatures to these hearing specialists. Weeks (10) proposed that saturniid hindwing tails might serve to divert bat attacks from essential body parts. We hypothesized that saturniid tails, spinning behind a flying moth (Movie S1) and reflecting sonar calls, serve as either a highly contrasting component of the primary echoic target or as an alternative target. We predicted that bats would aim their attacks at moth tails, instead of the wings or body, durin...

Naïve bats learn to avoid noxious fireflies fastest when integrating bioluminescent and echo-derived warnings.

Deimatic behaviours, also referred to as startle behaviours, are used against predators and rivals. Although many are spectacular, their proximate and ultimate causes remain unclear. In this review we aim to synthesise what is known about deimatic behaviour and identify knowledge gaps. We propose a working hypothesis for deimatic behaviour, and discuss the available evidence for the evolution, ontogeny, causation, and survival value of deimatic behaviour using Tinbergen's Four Questions as a framework. Our overarching aim is to direct future research by suggesting ways to address the most pressing questions in this field.

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Warning signals are well known in the visual system, but rare in other modalities. Some moths produce ultrasonic sounds to warn bats of noxious taste or to mimic unpalatable models. Here, we report results from a long-term study across the globe, assaying moth response to playback of bat echolocation. We tested 252 genera, spanning most families of large-bodied moths, and document anti-bat ultrasound production in 52 genera, with eight subfamily origins described. Based on acoustic analysis of ultrasonic emissions and palatability experiments with bats, it seems that acoustic warning and mimicry are the raison d'être for sound production in most moths. However, some moths use high-duty-cycle ultrasound capable of jamming bat sonar. In fact, we find preliminary evidence of independent origins of sonar jamming in at least six subfamilies. Palatability data indicate that jamming and warning are not mutually exclusive strategies. To explore the possible organization of anti-bat warning sounds into acoustic mimicry rings, we intensively studied a community of moths in Ecuador and, using machine-learning approaches, found five distinct acoustic clusters. While these data represent an early understanding of acoustic aposematism and mimicry across this megadiverse insect order, it is likely that ultrasonically signaling moths comprise one of the largest mimicry complexes on earth.