How a Tiny Beetle Uses Chemical Warfare Against Predators

Many insects have evolved to protect themselves from predators. For example, different types of beetles have adopted defenses like protective body shells and toxic secretions. One such beetle is the bombardier beetle. This YouTube video shows a bombardier beetle defending itself against a scorpion by producing a boiling hot chemical spray. As you can see in the clip, upon being sprayed, the scorpion immediately retreats. Although the scorpion is clearly larger and more powerful than the beetle, the beetle still manages to deter it with its chemical spray.

What Is a Bombardier Beetle?

Bombardier beetles are adephagan ground beetles and can be found across North America, South America, Europe, Africa, and Australia. They typically reside in woodlands and grasslands. Though these beetles are small in size (usually less than an inch long, according to the National Wildlife Federation), they’ve adopted powerful ways to survive against predators. This includes the beetle’s protective chemical spray.

How Do Bombardier Beetles Spray Predators? 

The National Wildlife Federation explained that the bombardier beetle shoots a boiling, irritating chemical liquid from its abdominal tip, which can rotate 270 degrees. The beetle’s abdomen is composed of two chambers. The first chamber, called the reservoir chamber, stores the chemicals hydrogen peroxide and hydroquinone. The second chamber, called the reaction chamber, contains enzymes like peroxidase and catalase, according to National Geographic.

Once the beetle perceives a threat, it opens the valve between its two chambers, mixing the chemicals and catalyst enzymes. This creates an explosive reaction that is expelled at the predator in rapid pulses, according to the Natural History Museum. Since the reaction chamber is located at the rear end of the beetle, the insect is able to keep its other organs safe from the toxic combination. While the protective spray can kill some predators, it often only does just enough damage to scare them away. As you can see in the YouTube video, the scorpion backs off from the beetle and flees the scene. However, it didn’t seem to be fatally injured.

Why Do Bombardier Beetles Spray?

Bombardier beetles spray to defend themselves against larger, threatening predators. The boiling, toxic liquid serves as a defense mechanism. For example, some of the beetle’s predators, like frogs and toads, often attempt to eat the insect. However, once the beetle releases its explosive spray, the predator typically spits out the beetle, which then has the chance to escape. Without this ability, bombardier beetles likely would not have survived for as long as they have.