Why You Don’t Want to Mess With a Bombardier Beetle

There are around 400,000 species of beetles on Earth, and they are a food source for countless animals. They have had to develop strategies to protect themselves from would-be predators, and one of the most impressive is that deployed by bombardier beetles. In this incredible clip, you see one using these spectacular defenses against a scorpion. Take a look and then read on for our explanation of how the beetle does this.

About Bombardier Beetles

The term ‘bombardier beetle’ refers to hundreds of species within the Carabidae family that are found worldwide, except in Antarctica. They generally live on forest floors, often amongst leaf litter, where they hunt for insects at night. However, they also face the threat of being hunted by other animals.

Chemical Defenses

Chemical defense is used by several types of beetles. Some secrete chemicals when they are attacked so that they either smell or taste foul and put predators off. The bombardiers, however, combine chemical warfare with explosions!

The chemical they use is called benzoquinone. While several other beetle species also use this chemical, bombardier beetles weaponize it more effectively by superheating and expelling it in an intense, pulsating jet. They do this by storing two types of chemicals—hydrogen peroxide and hydroquinone—in special protective chambers in their hindquarters. When the beetle is attacked, these chemicals are mixed together by a flexible membrane and a valve, producing an exothermic (heat-producing) reaction.

The mixture quickly reaches a boiling point and builds up enough pressure to be forcefully expelled from the beetle’s body. The reaction chamber is tough enough to withstand this process, and the fluid is instantly ejected once the reaction occurs. This weapon is not deployed randomly. It is ejected from the tip of their abdomen, which they can rotate to aim toward the area of their body that has detected the attack. Many bombardier beetles can discharge this chemical spray up to 20 times in rapid succession.

What Impact Does It Have On the Enemy?

At the very least, this defense startles predators and discourages them from continuing their attack. The predators often wander away and look for an easier target. Research has shown that predators such as ants and mantids do not usually suffer visible injuries after being sprayed, but they do exhibit short-term changes in behavior, likely due to the toxicity of the secretions. Getting sprayed in the face with boiling acid is enough to change anyone’s behavior!