Researchers Discover How Beetle Fires with its Butt

Researchers have discovered how the bombardier beetle shoots rapid bursts of hot chemicals from its rear.

University of Arizona researchers who termed the beetle's shooting 'machine-gun like', learnt that the beetle mixes hot explosive chemicals in a reaction chamber and then propels them with smoke from a nozzle in its rear at predators to ward them off. Researchers studied the beetle's reaction chamber and found it was made of material that protects the small-sized insect from the explosion.

"Understanding how these beetles produce - and survive - repetitive explosions could provide new design principles for technologies such as blast mitigation and propulsion," said the study's lead authors.

In the reaction chamber, researchers found a thin cuticle like area that they believe cuts off the supply of chemicals to the chamber, to facilitate pulse explosions that the beetle could sustain.

To verify their findings, researchers got 14 beetles to fire 30 times and record the firing through high intensity x-rays. The rays were aimed at the glands in such a manner that researchers were able to capture at about 2,000 frames per second, the internal workings of the reaction chamber.

"It turns out the expansion membrane of the reaction chamber acts as a passive closure mechanism, which is something that had not been described or even predicted before this study. We also discovered that the chamber's anatomy varies between female and male beetles," said researcher Wendy Moore.