By: Tina Wu

Some butterflies have a long black tails attached to the bottom of each wing. These ‘tails’ are thought to work like lizard tails, and help the victim get away from predators.

These ‘tails’ have evolved over many years, as shown in different types of moths and butterflies. They distract predators from important body parts, such as the head or abdomen. This was proved in an experiment conducted by a group studying at the National Museum of Natural History in Paris.

The experiment

Ariane Chotard, of the researchers, says that “A lot of these butterflies display tails, and we don’t really know why.”

The team wondered that since birds are attracted to patterns on butterfly wings, would they be attracted to tails? With this question in mind, they set up the project. They captured a few hundred sail swallowtails, or Iphiclides podalirius (IF-ih-KLIH-deez Poh-dul-IR-ee-us). These butterflies are native to Europe and Asia. They gained their name from their tail’s resemblance to the tails of swallows. The butterflies also have blue and orange spots that pop out against the yellow stripes at the base of their wings.

Having collected 138 swallowtails, the researchers found that almost half of the butterflies had lost at least tail. More than eight out of ten had damaged tails. They concluded that predators are likely more attracted to exotically-built prey.

To further prove their point, they captured song birds called “great tits.” They created fake butterflies with real swallowtail wings glued to cardboard. The scientists took a video showing the birds pecking the fake butterflies. After recording the video, they calculated how much force is needed to break each part of the wing. The results suggest that the ‘tails’ are the easiest part to break off because their veins are so brittle. 43 out of the 59 bird attacks targeted the lower parts of the wings, where the tails are located.