Bombardier beetles are famous in the insect world, not because they have colorfully patterned wings or a nasty bite, but because they have a very unique defense mechanism: When disturbed or attacked, the beetles produce an internal chemical explosion in their abdomen and then expel a jet of boiling, irritating liquid toward their attackers.

The liquid they eject is called benzoquinone, and they heat it to the temperature of boiling water before they shoot it out in an intense, pulsating jet. They are not the only insect to use this liquid, but they are the only ones to make it steaming hot. Not only that, they are the only ones to emit a pulsating stream, forcing out the liquid with unique precision five times faster!

Researchers were baffled as to how these beetles could produce this spray without causing themselves any physical damage. But, the question has now been answered! Researchers at MIT used high-speed synchrotron X-ray imaging to look inside the abdomens of living bombardier beetles during their chemical explosions. Check out the video below to see the X-ray footage in action!

The key is that they synthesize the chemical at the instant of use, mixing two chemical precursors in a protective chamber in their hindquarters. As the materials combine to form the irritant, they also give off intense heat that brings the liquid almost to the boiling point — and, in the process, generates the pressure needed to expel it in a jet.

The findings are published this week in the journal Science by MIT graduate student Eric Arndt, professor of materials science and engineering Christine Ortiz, Wah-Keat Lee of Brookhaven National Laboratory, and Wendy Moore of the University of Arizona.

Bombardier beetles lives on every continent except Antarctica and have virtually no predators. Sounds like a good life to me 🙂 Spray on, little dudes.