The Boiling Spray of the Bombardier Beetles
By Brayden Yin
The bombardier beetle is an interesting insect. It irritates its predators with a boiling spray that comes from its rear end. The chemicals used in the spray are so strong that it can kill ants and irritate human skin. The chemicals are heated to 212 degrees Fahrenheit, and the little beetle isn’t burned or hurt in any way.
Athula Attygalle is an analytical chemist at Stevens Institute of Technology in Hoboken, NJ. Attygale teamed up with other scientists to try and find the secret of the boiling spray.
One of the other researchers, Kipling Will, a biologist at the University of California at Berkeley collected 18 bombardiers and injected them with chemicals that were similar to the spray that the beetles use. The chemicals were very powerful and could kill lesser insects, but the bombardiers were not burned at all.
The scientists were able to see how the chemicals travel through the beetles until they are sprayed out as boiling acid. The chemicals are stored in a reservoir in the body until the beetle is threatened and the chemicals are needed. When a beetle is swallowed by a bird or a frog, valves open from the reservoir into an area of the body called the “reaction chamber.” There, they meet enzymes that heat the chemicals into their final, deadly acid. Then, “like detonating a bomb,” as Attygale says, the beetles spray out the boiling acid. The transformed chemicals are so irritating that the would-be predator spits the beetle out.
Bombardiers aren’t the only bugs that use chemicals for protection. Beetles, spiders, and millipedes all use chemicals to defend themselves. But bombardier beetles are the only ones to heat up the chemicals. Many insects also have chemical protection on their side, but the bombardier beetle’s might be the most powerful.