Caterpillars Appear to Be Defenseless

Most of us know that caterpillars are a significant part of life on our planet. They are a stage in many insects’ lives and a substantial food for many other life forms. Most caterpillars appear defenseless, so you might assume they are in danger of being wiped out, meaning there would be no more butterflies and moths.

Some caterpillars, such as those for monarch butterflies, have a poison defense. However, recent research has shown that caterpillars are not as helpless as we might think. They are designed with a defense mechanism called “electroreception,” which allows them to avoid being eaten by predator wasps.

The caterpillar can use the bristles that cover its body to detect the faint electric field generated by the wasp’s wing beats. Once it detects the presence of a wasp, the caterpillar assumes a defensive mode. It may remain coiled up with the bristles facing outward or even enter a biting defense.

Electroreception is common in aquatic animals, but this is the first time this predator-prey interaction has been recorded in land creatures. While most caterpillars appear to be defenseless, like all living things, they are carefully designed to have what they need to survive and prosper.

— John N. Clayton © 2024
Reference: “Warning Charge” in Scientific American, October 2024, pages 16-17