Evolution has repeatedly turned hawkmoth genitals into defensive tools

November 4, 2026 report Evolution has repeatedly turned hawkmoth genitals into defensive tools Paul Arnold Author Gaby Clark Scientific Editor Robert Egan Senior Editor The genital structures of male hawkmoths are lifesavers. By rubbing specialized scales on their genitals against parts of their abdomen, the nocturnal insects emit ultrasonic sounds that can potentially scramble the acoustic signals that bats use to hunt. These predator and defense systems have been locked in an evolutionary arms race for millions of years. Whenever one adapts, the other must respond. But questions remain about how often these defenses evolved independently and why different hawkmoth species developed different ways of producing ultrasound. Getting to the bottom of this involved a lot of moths. Ultrasonic defenses Paul K. Masonick at the University of Florida and colleagues tested hawkmoths' responses to recordings of attacking bats and gentle handling designed to simulate being caught by a predator. And they recorded any ultrasound the insects produced. Next, the research team performed detailed analyses of male genital structures from 124 species. They wanted to understand how the different sound-producing mechanisms worked and how they had evolved. To trace the history of these defenses, they also examined the evolutionary relationships between 310 hawkmoth species. The scientists discovered how many times nature has come up with different solutions to the same problem, as they report in a paper published in Proceedings of the Royal Society B. The anti-bat sound responses may have evolved independently up to seven times over roughly the past 30 million years. "Phylogenetic analyses reveal that stridulatory responses to bat echolocation evolved independently multiple times among hawkmoths within the past approximately 30 million years," wrote the scientists. However, the moths didn't all develop the same solution. Key differences The researchers identified three distinct mechanisms for producing ultrasound. Each involved rubbing specialized genital scales against a different structure on the abdomen: other scales, tiny spines or small bumps called nodules. But the study authors weren't finished yet. They also found that the three mechanisms produced different kinds of ultrasonic sounds that varied in pitch, the length of individual bursts and the amount of time moths spent making them. There were some other fascinating differences. Hawkmoths with hearing organs generally produced sounds with greater potential to interfere with bat sonar. "This suggests that the ability to detect bat calls may be closely linked to the production of anti-bat ultrasound with jamming potential." But some species without hearing organs also made ultrasound when touched. This could be to startle predators or mimic other moths rather than disrupt their hunting signals. Written for you by our author Paul Arnold, edited by Gaby Clark, and fact-checked and reviewed by Robert Egan—this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a donation (especially monthly). You'll get an ad-free account as a thank-you. Publication details Paul K. Masonick et al., The repeated evolution of anti-bat bioacoustics in hawkmoths, Proceedings of the Royal Society B: Biological Sciences (2026). DOI: 10.1098/rspb.2026.2303 Journal information: Proceedings B © 2026 Science X Network