This week has been full of unusual animals showing off their pipes (just look at this screaming marmot!), and these tiny mirid bugs (Macrolophus pygmaeus and Macrolophus costalis) are the latest performers.  

Their lion-like roars are too weak to be heard by humans, but Valerio Mazzoni of Italy's Edmund Mach Foundation and his team amplified them using a device called a laser vibrometer (we'll take three, please!), which can detect minute vibrations on solid surfaces, like the leaves of jungle plants. 

"When you listen to these sounds through headphones you’d think you were next to a tiger or lion," Mazzoni tells New Scientist. 

After countless hours of tuning in, the team discovered that most of these roars were made in tandem – a duet of sorts – that occurred when two mirids met on a leaf. When one insect roared, another responded. It's possible that this is something of a bravado battle, serving to establish dominance or attract a female. 

So, how do they do it? The short answer is, we don't really know. Many species of insects communicate through vibration (just think about a cricket's "chirp"), but most of them have to stay put while they do it. Not the little mirids: not only did the team observe them roaring and walking at the same time, but they also seem to do it without rubbing any parts of their bodies together. The team also found that these insects were roaring in a wide range of frequencies, allowing their calls to travel through the lush habitat without much trouble. 

"It must be a specific organ in the abdomen producing the roars,” Mazzoni speculates. But so far, nothing quite fits the bill. For now, the miniature mystery lives on, but the team hopes to unravel it in future studies.

Top header image: Arno Meintjes, Flickr