When a bat closes in, some hawkmoths fight back with their genitalia . By rasping specialized scales on their sex organs against structures on their abdomens, the moths unleash bursts of ultrasound that can scramble the sonar a hungry bat uses to lock onto prey.

But this acoustic counterattack is no evolutionary one-off. Relentless pressure from predators has pushed these otherwise tasty insects to reinvent this defensive tactic up to seven times throughout their evolution, with separate lineages arriving at distinct anatomical solutions to the same threat, researchers report November 4 in the Proceedings of the Royal Society B .

The findings suggest that the high-frequency acoustic skirmishes playing out overhead each night, beyond the range of human hearing, may be far more varied than scientists realized.

“Clearly the hawkmoths as a whole have more tricks up their sleeve,” says Marc Holderied, a sensory biologist and bioacoustics researcher at the University of Bristol in England who was not involved…