Some folks just can’t help being loud in bed, but noisy liaisons can lead to a swift death… at least for a housefly. In a German cowshed, Natterer’s bats eavesdrop on mating flies, homing in on their distinctive sexual buzzes.

Based on some old papers, Stefan Greif form the Max Planck Institute for Ornithology knew that Natterer’s bats shelter in cowsheds and sometimes feed on the flies within. What he didn’t know was how the bats catch insects that they shouldn’t be able to find. They hunt with sonar, releasing high-pitched squeaks and visualising the world in the returning echoes. Normally, the echoes rebounding from the flies would be masked by those bouncing off the rough, textured surface of