If you walk by a European river on a summer’s day, you might get to hear the animal kingdom’s champion vocalist. His song sounds like a train of chirps, and from a metre away, it’s as loud as whirring power tools. The din is all the more incredible because it is produced by an insect just two millimetres in length – the lesser water boatman, Micronecta scholtzi...How does such a tiny insect make such a loud noise? It’s not clear. It seems to do so by rubbing its ribbed penis against ridges on its belly, playing its genitals like a miniature fiddler. But the “bow” here is just 50 micrometres long, and there are no obvious body parts to amplify the noise.From the description here, I think calling this species the "lesser" water boatman is unwarranted. I'm impressed, I mean, talk about a skin flute*
*Sorry for that, I saw a chance and I took it.